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TDMS Study 05150-01 Pathology Tables

NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97
Route: DOSED FEED                                                                                                 Time: 11:13:41




       Facility:  TSI Mason Research

       Chemical CAS #:  298-59-9

       Lock Date:  02/06/92

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All






































                                                              Page   1

NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 7| 4| 7| 4| 7| 7| 7| 2| 6| 7| 7| 2| 6| 7| 6| 5| 4| 7| 7| 7| 7| 4|             
                             DAY ON TEST   | 8| 8| 4| 4| 6| 4| 5| 2| 4| 4| 8| 4| 4| 4| 8| 7| 4| 8| 6| 6| 4| 4| 4| 4| 6|             
                                           | 2| 2| 8| 6| 3| 8| 0| 9| 8| 8| 1| 8| 8| 8| 2| 7| 8| 0| 3| 4| 8| 8| 8| 8| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    | X           2  3                                                        2|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |             3                          2              4                  |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                          |             
      Dilatation                           |                                                                          |             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                    3                     |             
      Angiectasis                          |                                                                          |             
      Basophilic Focus                     |       X  X  X  X  X     X  X        X  X        X  X  X  X  X  X  X  X  X|             
      Clear Cell Focus                     |                X           X        X  X                 X               |             
      Developmental Malformation           |                                                                          |             
      Fatty Change                         |                                              2                           |             
      Granuloma                            |                3                                   3                     |             
      Hemorrhage                           |                                              2                           |             
      Hepatodiaphragmatic Nodule           | X              X                                            X  X  X      |             
      Necrosis, Focal                      |                                                                          |             
      Pigmentation, Bile                   |                                  4                                       |             
      Bile Duct, Hyperplasia               |                   1                                      1               |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                       +                  |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |          2  1           2  2  2  2     2     2  2                        |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                  2     2                                 |             
      Hyperplasia                          |                                                    2                     |             
      Hypoplasia                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Squamous                |                                                       3                  |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                  3           2                           |             
      Hypoplasia                           |                                                 2                        |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |          2     1                                               2     2  1|             
      Dilatation                           |                                  3                                       |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   2                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 7| 4| 7| 4| 7| 7| 7| 2| 6| 7| 7| 2| 6| 7| 6| 5| 4| 7| 7| 7| 7| 4|             
                             DAY ON TEST   | 8| 8| 4| 4| 6| 4| 5| 2| 4| 4| 8| 4| 4| 4| 8| 7| 4| 8| 6| 6| 4| 4| 4| 4| 6|             
                                           | 2| 2| 8| 6| 3| 8| 0| 9| 8| 8| 1| 8| 8| 8| 2| 7| 8| 0| 3| 4| 8| 8| 8| 8| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |          3                          2                                    |             
      Hyperplasia, Focal                   |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |          2                                      1                    2   |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                     3                                    |             
      Pars Distalis, Angiectasis, Focal    |                                                                          |             
      Pars Distalis, Angiectasis           |                                                                   3      |             
      Pars Distalis, Cyst                  | X     X           X     X                 X                          X   |             
      Pars Distalis, Hyperplasia, Focal    |                                                       2  1               |             
      Pars Distalis, Hyperplasia           |             3                                                            |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                2        3        2     2     2  1  1                     |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                 X                        |             
      Dilatation                           |                                                    3     3               |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
      Inflammation, Chronic                |             2     1        3                       3                    1|             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Dilatation                           |                               1     1                                    |             
      Endometrium, Cyst                    |                                                                          |             
      Endometrium, Fibrosis                |                                                                          |             
      Endometrium, Hyperplasia, Cystic     |                                              2                           |             
                                            __________________________________________________________________________|             
   Vagina                                  |                                                                          |             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   3                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 7| 4| 7| 4| 7| 7| 7| 2| 6| 7| 7| 2| 6| 7| 6| 5| 4| 7| 7| 7| 7| 4|             
                             DAY ON TEST   | 8| 8| 4| 4| 6| 4| 5| 2| 4| 4| 8| 4| 4| 4| 8| 7| 4| 8| 6| 6| 4| 4| 4| 4| 6|             
                                           | 2| 2| 8| 6| 3| 8| 0| 9| 8| 8| 1| 8| 8| 8| 2| 7| 8| 0| 3| 4| 8| 8| 8| 8| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |          3        2  2           2           4        4                  |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                  +           +                           |             
      Mediastinal, Congestion              |                                              3                           |             
      Pancreatic, Congestion               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Giant Cell                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                      3   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |    2                          2           2                              |             
      Granuloma                            |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                          |             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Fibrosis, Focal                      |                                              3                           |             
      Granuloma                            |                                                                          |             
      Hematopoietic Cell Proliferation     |                   4                                   3                  |             
      Infarct                              |                                                                          |             
      Pigmentation, Hemosiderin            |                                                                          |             
      Capsule, Fibrosis                    |                                        3                                 |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                             X     X      |             
      Galactocele, Multiple                |                                                                X         |             
      Lactation                            |       2        2           4     3  4  2     2                 3     3   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                                                          |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
      Ectopic Tissue                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   4                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 7| 4| 7| 4| 7| 7| 7| 2| 6| 7| 7| 2| 6| 7| 6| 5| 4| 7| 7| 7| 7| 4|             
                             DAY ON TEST   | 8| 8| 4| 4| 6| 4| 5| 2| 4| 4| 8| 4| 4| 4| 8| 7| 4| 8| 6| 6| 4| 4| 4| 4| 6|             
                                           | 2| 2| 8| 6| 3| 8| 0| 9| 8| 8| 1| 8| 8| 8| 2| 7| 8| 0| 3| 4| 8| 8| 8| 8| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                                                          |             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                      2                                                   |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Alveolar Epithelium, Metaplasia      |                                        2                       3         |             
      Peribronchial, Inflammation, Chronic | 2  2                          2           1                              |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                                  4                                       |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         | 2  2                          1           2                              |             
      Inflammation, Chronic                |             3     2                                      2              2|             
      Metaplasia, Squamous                 | 2           2                                                            |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Retina, Degeneration                 |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                         +                                                |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization, Focal                | 3                                                                        |             
      Mineralization                       |                         2  1        2                                2   |             
      Nephropathy                          |       2  2  1  2     1           3  2  4        2        2  1  1  2  1  1|             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Necrosis, Focal        |                                              2                           |             
      Renal Tubule, Pigmentation, Bile     |                                              3        3                  |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |             1                                                            |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   5                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 4| 7| 4| 4| 7| 7| 2| 6| 2| 7| 7| 4| 6| 7| 7| 7| 4| 6| 2| 5| 7| 2| 7| 7|             
                             DAY ON TEST   | 6| 6| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 6| 6| 2| 4| 4| 6| 6| 8| 5| 4| 6| 4| 4|             
                                           | 3| 3| 7| 3| 4| 7| 7| 2| 0| 1| 7| 7| 3| 0| 8| 7| 7| 3| 2| 1| 1| 7| 0| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                   2           2                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    | 2                                   2                          2         |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                      3   |             
      Dilatation                           |                                                                   3      |             
      Parasite Metazoan                    |                                              4              4  3         |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                      4   |             
      Angiectasis                          |                                                                          |             
      Basophilic Focus                     | X  X     X  X     X     X     X  X        X  X  X           X  X        X|             
      Clear Cell Focus                     |                   X                                            X         |             
      Developmental Malformation           |                                                                          |             
      Fatty Change                         |                                        4              3           2      |             
      Granuloma                            |                                                                2         |             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Pigmentation, Bile                   |                                                                          |             
      Bile Duct, Hyperplasia               |                                     2                                    |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +                                +                                 |             
      Fat, Necrosis                        |       4                                2                                 |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |       1                                               2                  |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Hypoplasia                           |                                        2                                 |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Squamous                |       3                                                                  |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                        4                                 |             
      Hypoplasia                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |    1              2     2     3  2  1  2  1  1  3     1     1  3     3   |             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   6                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 4| 7| 4| 4| 7| 7| 2| 6| 2| 7| 7| 4| 6| 7| 7| 7| 4| 6| 2| 5| 7| 2| 7| 7|             
                             DAY ON TEST   | 6| 6| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 6| 6| 2| 4| 4| 6| 6| 8| 5| 4| 6| 4| 4|             
                                           | 3| 3| 7| 3| 4| 7| 7| 2| 0| 1| 7| 7| 3| 0| 8| 7| 7| 3| 2| 1| 1| 7| 0| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |                            1                                             |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                               2                                          |             
      Hyperplasia, Focal                   |                   2                                                      |             
      Vacuolization Cytoplasmic            |                         3                             2                  |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                  2                    2                  |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Pars Distalis, Angiectasis, Focal    | 2                                                                        |             
      Pars Distalis, Angiectasis           |    4           3              4        3                                 |             
      Pars Distalis, Cyst                  |       X                                      X                           |             
      Pars Distalis, Hyperplasia, Focal    |                2  4           3  3  1                                   3|             
      Pars Distalis, Hyperplasia           |          3                                                               |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |             2                 2  1                                      2|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                   X                       X                              |             
      Dilatation                           |                         3     4                                      3  3|             
      Inflammation, Acute                  |                                                       2                  |             
      Inflammation, Chronic, Focal         |                      2     2                             1               |             
      Inflammation, Chronic                |    1  2  2  1                       2              1              1      |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Inflammation, Chronic, Focal         |    2                                                                     |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                              4                           |             
      Dilatation                           |          3                 2                                   3         |             
      Endometrium, Cyst                    |                                                                          |             
      Endometrium, Fibrosis                |                                                    2                     |             
      Endometrium, Hyperplasia, Cystic     |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                                                                          |             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   7                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 4| 7| 4| 4| 7| 7| 2| 6| 2| 7| 7| 4| 6| 7| 7| 7| 4| 6| 2| 5| 7| 2| 7| 7|             
                             DAY ON TEST   | 6| 6| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 6| 6| 2| 4| 4| 6| 6| 8| 5| 4| 6| 4| 4|             
                                           | 3| 3| 7| 3| 4| 7| 7| 2| 0| 1| 7| 7| 3| 0| 8| 7| 7| 3| 2| 1| 1| 7| 0| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |       3           2                    4                    4        3   |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                        +              +                  |             
      Mediastinal, Congestion              |                                                                          |             
      Pancreatic, Congestion               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                   2      |             
      Giant Cell                           |                                                          2               |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                   3      |             
      Depletion Lymphoid                   |                         4                                                |             
      Giant Cell                           |                      2     1                             3        2      |             
      Granuloma                            |                                                                3         |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                          |             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                         3                 2                              |             
      Fibrosis, Focal                      |                                                                          |             
      Granuloma                            |                                                                4         |             
      Hematopoietic Cell Proliferation     |                                                             4        4   |             
      Infarct                              |                                                                          |             
      Pigmentation, Hemosiderin            |                                                                   2      |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                         4                                         3      |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                   X           X                 X                        |             
      Galactocele, Multiple                |                                                                          |             
      Lactation                            |       3        2  3     4        3     2  3     2           2        4  3|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                  3                          3            |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |       +                                                                  |             
      Ectopic Tissue                       |       X                                                                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   8                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 4| 7| 4| 4| 7| 7| 2| 6| 2| 7| 7| 4| 6| 7| 7| 7| 4| 6| 2| 5| 7| 2| 7| 7|             
                             DAY ON TEST   | 6| 6| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 6| 6| 2| 4| 4| 6| 6| 8| 5| 4| 6| 4| 4|             
                                           | 3| 3| 7| 3| 4| 7| 7| 2| 0| 1| 7| 7| 3| 0| 8| 7| 7| 3| 2| 1| 1| 7| 0| 7| 7|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    0 PPM                                  | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                         4                 3                          3   |             
      Congestion                           |                                                                   1      |             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |                                                                          |             
      Necrosis, Focal                      |                                        4              3                  |             
      Alveolar Epithelium, Metaplasia      |                                                                          |             
      Peribronchial, Inflammation, Chronic |                      2     1                             2               |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |          3                                                        4      |             
      Inflammation, Acute                  |          3              4                                                |             
      Inflammation, Chronic, Focal         |                      2     2                             2               |             
      Inflammation, Chronic                | 2  2        1                       2              2                     |             
      Metaplasia, Squamous                 |                                                          2               |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Retina, Degeneration                 |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |    +                                                                     |             
      Hyperplasia                          |    2                                                                     |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization, Focal                |                            2                                             |             
      Mineralization                       |                   1                    2        1                 2  4  2|             
      Nephropathy                          | 2  1  2     2  2  1     3  1  2  4  1     2  1              2  2     3  1|             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Necrosis, Focal        |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |                                                       3                  |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page   9                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 6| 6| 5| 2| 7| 7| 6| 7| 7| 6| 6| 2| 7| 7| 7| 6| 2| 7| 7|              |            |
                             DAY ON TEST   | 6| 7| 1| 7| 8| 4| 4| 8| 4| 4| 5| 4| 8| 4| 4| 4| 6| 8| 4| 4|              |            |
                                           | 4| 5| 3| 5| 2| 7| 7| 4| 7| 7| 0| 9| 2| 7| 7| 7| 8| 1| 7| 7|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|              |      A     |
    0 PPM                                  | 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Parasite Metazoan                    |                         2                 3                              |      8  2.3|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Parasite Metazoan                    |                                                 3                        |      7  2.6|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  66        |
      Autolysis                            |                                                                          |      1  3.0|
      Dilatation                           |                                                                          |      1  3.0|
      Parasite Metazoan                    |                                                                          |      3  3.7|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  66        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Abscess                              |                                                                          |      2  3.5|
      Angiectasis                          |                                                 2                        |      1  2.0|
      Basophilic Focus                     |    X           X  X        X           X  X  X  X     X  X               |     42     |
      Clear Cell Focus                     |                   X     X              X        X                        |     11     |
      Developmental Malformation           |                                  X                                       |      1     |
      Fatty Change                         |    3  3                       4  3                                       |      8  3.0|
      Granuloma                            |                                                                          |      3  2.7|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hepatodiaphragmatic Nodule           |       X           X                                                      |      7     |
      Necrosis, Focal                      |          3                                                               |      1  3.0|
      Pigmentation, Bile                   |                                                                          |      1  4.0|
      Bile Duct, Hyperplasia               | 1                                                                        |      4  1.3|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                       +                  |   4        |
      Fat, Necrosis                        |                                                       4                  |      3  3.3|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Acinus, Atrophy                      |                         3        4                                       |     13  2.1|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Cellular                   |                                                                          |      2  2.0|
      Hyperplasia                          |                                                                          |      1  2.0|
      Hypoplasia                           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia, Squamous                |                                                                          |      2  3.0|
      Ulcer                                |       4                                                                  |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Erosion                              |    4     3                                                               |      5  3.2|
      Hypoplasia                           |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  10                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 6| 6| 5| 2| 7| 7| 6| 7| 7| 6| 6| 2| 7| 7| 7| 6| 2| 7| 7|              |            |
                             DAY ON TEST   | 6| 7| 1| 7| 8| 4| 4| 8| 4| 4| 5| 4| 8| 4| 4| 4| 6| 8| 4| 4|              |            |
                                           | 4| 5| 3| 5| 2| 7| 7| 4| 7| 7| 0| 9| 2| 7| 7| 7| 8| 1| 7| 7|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|              |      A     |
    0 PPM                                  | 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       |                   4     2                 2  2  3        3               |     25  2.0|
      Dilatation                           |                                                                          |      1  3.0|
      Inflammation, Chronic, Focal         |                                     1                                    |      2  1.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cytoplasmic Alteration, Focal        |                                                                          |      3  2.3|
      Hyperplasia, Focal                   |                                                                          |      1  2.0|
      Vacuolization Cytoplasmic            |                                  3                                       |      3  2.7|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia, Focal                   |                               4  2                                       |      7  2.1|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Hyperplasia, Focal                   |       2                                      2                           |      2  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hemorrhage                           |                                                                          |      1  3.0|
      Pars Distalis, Angiectasis, Focal    |                                                                          |      1  2.0|
      Pars Distalis, Angiectasis           |                                                                          |      5  3.4|
      Pars Distalis, Cyst                  |                                     X              X     X               |     11     |
      Pars Distalis, Hyperplasia, Focal    |    3  3              4           2        4              3               |     14  2.7|
      Pars Distalis, Hyperplasia           |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      C-Cell, Hyperplasia                  | 2                       2  3                                             |     14  1.9|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  M  M  +  +  +  +  +  +  M  +  +  +  +  +               |  65        |
      Cyst                                 |                                                          X               |      4     |
      Dilatation                           |                         4  4  4              4                           |     10  3.5|
      Inflammation, Acute                  |                         2              3     2                           |      4  2.3|
      Inflammation, Chronic, Focal         |             2                       2              1                     |      6  1.7|
      Inflammation, Chronic                | 1                                                                        |     13  1.6|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cyst                                 |                                                          X               |      1     |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  11                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 6| 6| 5| 2| 7| 7| 6| 7| 7| 6| 6| 2| 7| 7| 7| 6| 2| 7| 7|              |            |
                             DAY ON TEST   | 6| 7| 1| 7| 8| 4| 4| 8| 4| 4| 5| 4| 8| 4| 4| 4| 6| 8| 4| 4|              |            |
                                           | 4| 5| 3| 5| 2| 7| 7| 4| 7| 7| 0| 9| 2| 7| 7| 7| 8| 1| 7| 7|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|              |      A     |
    0 PPM                                  | 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic, Focal         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Abscess                              |                                                                          |      1  4.0|
      Dilatation                           |                                                       3  3               |      7  2.3|
      Endometrium, Cyst                    |                   X                                                      |      1     |
      Endometrium, Fibrosis                |                                                                          |      1  2.0|
      Endometrium, Hyperplasia, Cystic     |                            2                                             |      2  2.0|
                                            __________________________________________________________________________|____________|
   Vagina                                  |    +                                                                     |   1        |
      Dilatation                           |    3                                                                     |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood                                   |       +                       +                                          |   2        |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |    2  3              3        4  4        2                              |     17  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |       +  +           +        +                                          |   8        |
      Mediastinal, Congestion              |                                                                          |      1  3.0|
      Pancreatic, Congestion               |       3                                                                  |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  2.0|
      Giant Cell                           |                                                                          |      1  2.0|
      Infiltration Cellular, Plasma Cell   |    4                                                                     |      1  4.0|
      Infiltration Cellular, Histiocyte    |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                         3                       4                        |      3  3.3|
      Depletion Lymphoid                   |                                                                          |      1  4.0|
      Giant Cell                           |             4                       2              2                     |     10  2.2|
      Granuloma                            |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Autolysis                            |                      3                                                   |      1  3.0|
      Congestion                           |                                  3                                       |      1  3.0|
      Depletion Lymphoid                   |    2                                         2                           |      4  2.3|
      Fibrosis, Focal                      |                                                                          |      1  3.0|
      Granuloma                            |                                                                          |      1  4.0|
      Hematopoietic Cell Proliferation     |                                                                          |      4  3.8|
      Infarct                              |          4                                                               |      1  4.0|
      Pigmentation, Hemosiderin            |                                                                          |      1  2.0|
      Capsule, Fibrosis                    |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Depletion Lymphoid                   |                                                                          |      2  3.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  12                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 6| 6| 5| 2| 7| 7| 6| 7| 7| 6| 6| 2| 7| 7| 7| 6| 2| 7| 7|              |            |
                             DAY ON TEST   | 6| 7| 1| 7| 8| 4| 4| 8| 4| 4| 5| 4| 8| 4| 4| 4| 6| 8| 4| 4|              |            |
                                           | 4| 5| 3| 5| 2| 7| 7| 4| 7| 7| 0| 9| 2| 7| 7| 7| 8| 1| 7| 7|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|              |      A     |
    0 PPM                                  | 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Galactocele                          |                   X                       X           X  X               |      9     |
      Galactocele, Multiple                |                                                                          |      1     |
      Lactation                            |    2  2        2  4  2  4  2  3  3     3  3  4  2     3  3               |     35  2.8|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperkeratosis                       |                                              2                           |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |    2  3                       3                          4               |      6  3.0|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
      Ectopic Tissue                       |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Compression                          |                                                 3                        |      4  3.3|
      Congestion                           |                                                                          |      1  1.0|
      Hemorrhage                           |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Granuloma                            |                                     2                                    |      1  2.0|
      Necrosis, Focal                      |          4                                                               |      3  3.7|
      Alveolar Epithelium, Metaplasia      |                                                                          |      2  2.5|
      Peribronchial, Inflammation, Chronic |             2                       2              2                     |     10  1.8|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Fungus                               |                            4                                             |      4  3.8|
      Inflammation, Acute                  |                                                                          |      2  3.5|
      Inflammation, Chronic, Focal         |             2                       2              2                     |     10  1.9|
      Inflammation, Chronic                | 2                                                                        |     10  2.0|
      Metaplasia, Squamous                 |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |    +                                                                     |   1        |
                                            __________________________________________________________________________|____________|
   Eye                                     |       +                       +     +                                    |   3        |
      Retina, Degeneration                 |                               4                                          |      1  4.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  13                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 6| 6| 5| 2| 7| 7| 6| 7| 7| 6| 6| 2| 7| 7| 7| 6| 2| 7| 7|              |            |
                             DAY ON TEST   | 6| 7| 1| 7| 8| 4| 4| 8| 4| 4| 5| 4| 8| 4| 4| 4| 6| 8| 4| 4|              |            |
                                           | 4| 5| 3| 5| 2| 7| 7| 4| 7| 7| 0| 9| 2| 7| 7| 7| 8| 1| 7| 7|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|              |      A     |
    0 PPM                                  | 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 SPECIAL SENSES SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   2        |
      Hyperplasia                          |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |    +                                                                     |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Mineralization, Focal                |                                                                          |      2  2.5|
      Mineralization                       |          3     3     4  1  3     1        3     3     2                  |     19  2.2|
      Nephropathy                          | 1  2  2        1  2     2  3  2  1     1     3  2     3  2               |     46  1.9|
      Renal Tubule, Degeneration, Granular |          3                                                               |      1  3.0|
      Renal Tubule, Necrosis, Focal        |                                                                          |      1  2.0|
      Renal Tubule, Pigmentation, Bile     |       2                                                                  |      4  2.8|
      Renal Tubule, Regeneration           |             1                                                            |      1  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Inflammation, Chronic, Focal         |                                                                          |      1  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  14                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 4| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 4| 7| 7| 7| 7| 2| 2| 4| 7| 4| 7|             
                             DAY ON TEST   | 2| 6| 5| 4| 1| 4| 4| 4| 4| 4| 8| 4| 6| 4| 6| 4| 4| 4| 2| 8| 8| 9| 4| 6| 4|             
                                           | 1| 3| 0| 3| 2| 3| 3| 3| 4| 3| 5| 3| 0| 3| 4| 1| 4| 4| 8| 1| 2| 4| 4| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    100 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                          X               |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +|             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2                                                                        |             
      Basophilic Focus                     | X  X  X  X     X  X  X  X  X  X  X  X  X  X     X  X  X        X  X  X   |             
      Clear Cell Focus                     | X                          X     X                                X      |             
      Depletion Glycogen                   |                                                                          |             
      Developmental Malformation           |                                                                      X   |             
      Fatty Change                         |                                                                1         |             
      Granuloma                            |                            3                          4                  |             
      Hemorrhage                           |                                                                          |             
      Hepatodiaphragmatic Nodule           |       X                                                                  |             
      Necrosis, Focal                      |                                              4                          2|             
      Bile Duct, Hyperplasia               |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |          +                       +                                +      |             
      Inflammation, Granulomatous          |                                                                          |             
      Fat, Necrosis                        |          3                       4                                4      |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |                                                                          |             
      Acinus, Atrophy                      |          2     2              2        4           4              2     3|             
      Acinus, Hyperplasia, Focal           |                                  2                                       |             
      Artery, Inflammation, Chronic        |       3                                                                  |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                       3                  |             
      Inflammation, Subacute               |                                                       3                  |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                       3                  |             
      Erosion                              |                                     2                                   3|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |       1                          2           2     3  2           2      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  15                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 4| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 4| 7| 7| 7| 7| 2| 2| 4| 7| 4| 7|             
                             DAY ON TEST   | 2| 6| 5| 4| 1| 4| 4| 4| 4| 4| 8| 4| 6| 4| 6| 4| 4| 4| 2| 8| 8| 9| 4| 6| 4|             
                                           | 1| 3| 0| 3| 2| 3| 3| 3| 4| 3| 5| 3| 0| 3| 4| 1| 4| 4| 8| 1| 2| 4| 4| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    100 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
      Pigmentation                         |          3                                                               |             
      Coronary Artery, Inflammation,       |                                                                          |             
          Chronic                          |                                           3                              |             
      Myocardium, Inflammation, Chronic,   |                                                                          |             
           Focal                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        | 2                                                     3                 4|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                                                          |             
      Hyperplasia, Focal                   |                   1                                                     2|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                     1                                    |             
      Hypoplasia                           |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  M|             
      Hyperplasia, Focal                   |                                                                          |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Pars Distalis, Angiectasis           |                            2                                             |             
      Pars Distalis, Cyst                  |    X                                                                     |             
      Pars Distalis, Hyperplasia, Focal    |                3     2  2  2           1        3  3                    4|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |       1  2     2  2     3                 1                              |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |          2                                                               |             
      Cyst                                 |                               X                                          |             
      Depletion Cellular                   |                                                                          |             
      Dilatation                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         |                                                          2  2            |             
      Inflammation, Chronic                |    2  1                    2                                             |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |    2              4     3                                                |             
      Thrombosis                           |                                                                          |             
      Endometrium, Cyst                    |                            X                                             |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  16                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 4| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 4| 7| 7| 7| 7| 2| 2| 4| 7| 4| 7|             
                             DAY ON TEST   | 2| 6| 5| 4| 1| 4| 4| 4| 4| 4| 8| 4| 6| 4| 6| 4| 4| 4| 2| 8| 8| 9| 4| 6| 4|             
                                           | 1| 3| 0| 3| 2| 3| 3| 3| 4| 3| 5| 3| 0| 3| 4| 1| 4| 4| 8| 1| 2| 4| 4| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    100 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                                                                          |             
      Exudate                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                            4                 2     3           2        4|             
      Myelofibrosis                        |                                                             1            |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                            +  +                                         +|             
      Mediastinal, Angiectasis             |                                                                          |             
      Pancreatic, Angiectasis              |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Cyst                                 |                            X                                             |             
      Giant Cell                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Giant Cell                           |                                                          2  2            |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   | 2                                                                        |             
      Fibrosis, Focal                      |                                                                          |             
      Hematopoietic Cell Proliferation     |                                                                4         |             
      Necrosis, Focal                      |                                                                         3|             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   | 2                                                                        |             
      Lymphatic, Angiectasis               |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                      X                 X              X                  |             
      Galactocele, Multiple                |                                                                          |             
      Lactation                            | 4        3  3     2  2  3  3        4  4     2     3  4           2      |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                                                                          |             
      Cyst Epithelial Inclusion            |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                        X        2  4                     |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | X                                   X                 4                  |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  17                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 4| 4| 7| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 4| 7| 7| 7| 7| 2| 2| 4| 7| 4| 7|             
                             DAY ON TEST   | 2| 6| 5| 4| 1| 4| 4| 4| 4| 4| 8| 4| 6| 4| 6| 4| 4| 4| 2| 8| 8| 9| 4| 6| 4|             
                                           | 1| 3| 0| 3| 2| 3| 3| 3| 4| 3| 5| 3| 0| 3| 4| 1| 4| 4| 8| 1| 2| 4| 4| 4| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    100 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                                                                         3|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Peribronchial, Inflammation, Chronic |                                                          2  2            |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         |                                                          2  2            |             
      Inflammation, Chronic                |    1  2                                   2                          2   |             
      Metaplasia, Squamous                 |                                                          2               |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                  +                                       |             
      Cataract                             |                                  2                                       |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                   +                                                      |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Cyst                                 |                                              X                           |             
      Glomerulosclerosis                   |                                                                          |             
      Mineralization, Focal                |                                                          1               |             
      Mineralization                       | 1        1  2  2  3  2     1     2              1  2  3           1      |             
      Nephropathy                          | 3     2  1  2  2  2  2  1  2  1  2  3  1  2     1  1  3           1      |             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |                            2  2                                         3|             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +|             
      Hyperplasia, Focal                   |                                                    3                     |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  18                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 2| 2| 4| 4| 7| 6| 6| 7| 7| 7| 2| 7| 7| 4| 7| 4| 4| 7| 6| 7| 2| 7|             
                             DAY ON TEST   | 8| 8| 4| 8| 8| 6| 6| 4| 7| 3| 2| 4| 4| 8| 4| 2| 6| 4| 6| 6| 4| 8| 4| 8| 4|             
                                           | 2| 1| 4| 2| 1| 4| 3| 4| 1| 2| 9| 3| 4| 2| 4| 0| 4| 4| 4| 4| 4| 1| 7| 1| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    100 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |       2                                         2     2  2               |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                  2        4     4     2                  |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                        X                       2        4|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Basophilic Focus                     |       X        X  X  X           X  X     X  X  X  X  X     X  X  X     X|             
      Clear Cell Focus                     |       X              X        X                                          |             
      Depletion Glycogen                   |                                  2                                       |             
      Developmental Malformation           |                                                                          |             
      Fatty Change                         |                         3  4  2                                          |             
      Granuloma                            |                                        1              2                  |             
      Hemorrhage                           |                                                                   3      |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Necrosis, Focal                      |                         1     2              2                           |             
      Bile Duct, Hyperplasia               |                                                 2                        |             
                                            __________________________________________________________________________|             
   Mesentery                               |                      +        +        +                       +         |             
      Inflammation, Granulomatous          |                                                                2         |             
      Fat, Necrosis                        |                      4        3        3                                 |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Liver                        |                                     X                                    |             
      Acinus, Atrophy                      |    1              2                                                      |             
      Acinus, Hyperplasia, Focal           |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
      Inflammation, Subacute               |                                                                          |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Erosion                              |                         2  4     3           3                           |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |       2              3        2  2        1  1     1     1        1      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  19                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 2| 2| 4| 4| 7| 6| 6| 7| 7| 7| 2| 7| 7| 4| 7| 4| 4| 7| 6| 7| 2| 7|             
                             DAY ON TEST   | 8| 8| 4| 8| 8| 6| 6| 4| 7| 3| 2| 4| 4| 8| 4| 2| 6| 4| 6| 6| 4| 8| 4| 8| 4|             
                                           | 2| 1| 4| 2| 1| 4| 3| 4| 1| 2| 9| 3| 4| 2| 4| 0| 4| 4| 4| 4| 4| 1| 7| 1| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    100 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |    1                                   1                             1   |             
      Pigmentation                         |                                                                          |             
      Coronary Artery, Inflammation,       |                                                                          |             
          Chronic                          |                                                                          |             
      Myocardium, Inflammation, Chronic,   |                                                                          |             
           Focal                           |                                                 2                        |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                     2     3                              |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                                                          |             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
      Hypoplasia                           |             1                                                           3|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M|             
      Hyperplasia, Focal                   |                                                                          |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Pars Distalis, Angiectasis           |                   2     3                                                |             
      Pars Distalis, Cyst                  |    X                                                        X        X   |             
      Pars Distalis, Hyperplasia, Focal    |       1                 3     2                       3  2               |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                1     4              4                    1               |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                        2                       4         |             
      Cyst                                 |                                                             X  X  X      |             
      Depletion Cellular                   |                               3                                          |             
      Dilatation                           |                            4                                             |             
      Inflammation, Acute                  |                                              2              3            |             
      Inflammation, Chronic, Focal         | 1  2     1  2                                                            |             
      Inflammation, Chronic                |                2  2                             2        2               |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Dilatation                           |             2                                               4            |             
      Thrombosis                           |                            X                                             |             
      Endometrium, Cyst                    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  20                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 2| 2| 4| 4| 7| 6| 6| 7| 7| 7| 2| 7| 7| 4| 7| 4| 4| 7| 6| 7| 2| 7|             
                             DAY ON TEST   | 8| 8| 4| 8| 8| 6| 6| 4| 7| 3| 2| 4| 4| 8| 4| 2| 6| 4| 6| 6| 4| 8| 4| 8| 4|             
                                           | 2| 1| 4| 2| 1| 4| 3| 4| 1| 2| 9| 3| 4| 2| 4| 0| 4| 4| 4| 4| 4| 1| 7| 1| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    100 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                            +                                             |             
      Exudate                              |                            X                                             |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               4  3        2                              |             
      Myelofibrosis                        | 1                       4                                                |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                      +                                                   |             
      Mediastinal, Angiectasis             |                      3                                                   |             
      Pancreatic, Angiectasis              |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                         3                                                |             
      Cyst                                 |                                                                          |             
      Giant Cell                           |                                        2                                 |             
      Inflammation, Acute                  |                      3                                                   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Giant Cell                           | 4  1     2  1                          3                             3   |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
      Fibrosis, Focal                      |                            3                                             |             
      Hematopoietic Cell Proliferation     |                                  4                                       |             
      Necrosis, Focal                      |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
      Lymphatic, Angiectasis               |                               3                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                          |             
      Galactocele, Multiple                |                                                                          |             
      Lactation                            |                      4  4  4  3  3  3        2     3           4  2     2|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                      3                                                   |             
      Cyst Epithelial Inclusion            |                                                                   X      |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                            2  4                                          |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |       +                                                                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                     3        4                           |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  21                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 2| 2| 4| 4| 7| 6| 6| 7| 7| 7| 2| 7| 7| 4| 7| 4| 4| 7| 6| 7| 2| 7|             
                             DAY ON TEST   | 8| 8| 4| 8| 8| 6| 6| 4| 7| 3| 2| 4| 4| 8| 4| 2| 6| 4| 6| 6| 4| 8| 4| 8| 4|             
                                           | 2| 1| 4| 2| 1| 4| 3| 4| 1| 2| 9| 3| 4| 2| 4| 0| 4| 4| 4| 4| 4| 1| 7| 1| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    100 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                  2        2                              |             
      Peribronchial, Inflammation, Chronic | 2  2     1  2                          2                             2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                                                    2                     |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         | 2  2     2  2                          2                             2   |             
      Inflammation, Chronic                |                3  2                             2     2  1        2      |             
      Metaplasia, Squamous                 |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cataract                             |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Glomerulosclerosis                   |                                                                          |             
      Mineralization, Focal                | 1  1     1  1                                                            |             
      Mineralization                       |                                           1                       1     1|             
      Nephropathy                          |       2        2  2  3  1     1  2  4     1  3  2  2  2  1     2  3     1|             
      Renal Tubule, Degeneration, Granular |                            2                                             |             
      Renal Tubule, Pigmentation, Bile     |                         2     2                                          |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  22                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 6| 7| 7| 4| 4| 2| 7| 7| 7| 7| 5| 7| 6| 7|              |            |
                             DAY ON TEST   | 4| 6| 8| 4| 4| 4| 1| 4| 1| 6| 8| 8| 4| 4| 4| 4| 7| 4| 9| 1|              |            |
                                           | 4| 3| 2| 7| 7| 7| 9| 4| 3| 4| 8| 1| 7| 7| 7| 4| 9| 7| 9| 8|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|              |      A     |
    100 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                        3                                 |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Parasite Metazoan                    |       X                 4     2                                          |      7  2.3|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +               |  67        |
      Parasite Metazoan                    |                                                                          |      5  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +               |  65        |
      Parasite Metazoan                    |                                                                          |      3  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +               |  66        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  A               |  63        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  A               |  63        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Atrophy                              |                                                                          |      1  2.0|
      Basophilic Focus                     | X  X     X  X  X     X  X  X        X  X     X     X  X                  |     48     |
      Clear Cell Focus                     |                                                    X                     |      8     |
      Depletion Glycogen                   |                                                                          |      1  2.0|
      Developmental Malformation           |                                                                          |      1     |
      Fatty Change                         |                   4                                      4               |      6  3.0|
      Granuloma                            |                            2                                             |      5  2.4|
      Hemorrhage                           |                                                                          |      1  3.0|
      Hepatodiaphragmatic Nodule           |                      X                             X                     |      3     |
      Necrosis, Focal                      |                                                                          |      5  2.2|
      Bile Duct, Hyperplasia               |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   7        |
      Inflammation, Granulomatous          |                                                                          |      1  2.0|
      Fat, Necrosis                        |                                                                          |      6  3.5|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Ectopic Liver                        |                                           X                              |      2     |
      Acinus, Atrophy                      | 2                                                     1                  |     11  2.3|
      Acinus, Hyperplasia, Focal           |                                                                          |      1  2.0|
      Artery, Inflammation, Chronic        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Inflammation, Chronic, Focal         |    1                                         2                           |      2  1.5|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Hyperkeratosis                       |                                                                          |      1  3.0|
      Inflammation, Subacute               |                                                                          |      1  3.0|
      Ulcer                                |                                                          2               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Depletion Cellular                   |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  23                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 6| 7| 7| 4| 4| 2| 7| 7| 7| 7| 5| 7| 6| 7|              |            |
                             DAY ON TEST   | 4| 6| 8| 4| 4| 4| 1| 4| 1| 6| 8| 8| 4| 4| 4| 4| 7| 4| 9| 1|              |            |
                                           | 4| 3| 2| 7| 7| 7| 9| 4| 3| 4| 8| 1| 7| 7| 7| 4| 9| 7| 9| 8|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|              |      A     |
    100 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Erosion                              |                                                 4        2               |      8  2.9|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       |          3  1        4  2           1  2           2     2               |     23  1.9|
      Inflammation, Chronic, Focal         |       1                          1                                       |      5  1.0|
      Pigmentation                         |                                                                          |      1  3.0|
      Coronary Artery, Inflammation,       |                                                                          |            |
          Chronic                          |                                                                          |      1  3.0|
      Myocardium, Inflammation, Chronic,   |                                                                          |            |
           Focal                           |                            2                                             |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cytoplasmic Alteration, Focal        | 3                                            2        3                  |      8  2.8|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Fibrosis                             |                                           4                              |      1  4.0|
      Hyperplasia, Focal                   |    2           3                                                         |      4  2.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hyperplasia                          |                                                                          |      1  1.0|
      Hypoplasia                           |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  66        |
      Hyperplasia, Focal                   |                                                       2                  |      1  2.0|
      Hyperplasia                          |                                                          3               |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hemorrhage                           |                         4                                                |      1  4.0|
      Pars Distalis, Angiectasis           |                                                                          |      3  2.3|
      Pars Distalis, Cyst                  |    X  X                                         X                        |      7     |
      Pars Distalis, Hyperplasia, Focal    |                4           2                    1                        |     16  2.4|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      C-Cell, Hyperplasia                  |                                     1                 2                  |     12  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Abscess                              |                            3                                             |      4  2.8|
      Cyst                                 |                                                                          |      4     |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  24                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 6| 7| 7| 4| 4| 2| 7| 7| 7| 7| 5| 7| 6| 7|              |            |
                             DAY ON TEST   | 4| 6| 8| 4| 4| 4| 1| 4| 1| 6| 8| 8| 4| 4| 4| 4| 7| 4| 9| 1|              |            |
                                           | 4| 3| 2| 7| 7| 7| 9| 4| 3| 4| 8| 1| 7| 7| 7| 4| 9| 7| 9| 8|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|              |      A     |
    100 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Depletion Cellular                   |                                              2                           |      2  2.5|
      Dilatation                           |                         4           3  3                                 |      4  3.5|
      Inflammation, Acute                  |                                                                          |      2  2.5|
      Inflammation, Chronic, Focal         |       2                          2                                       |      8  1.8|
      Inflammation, Chronic                |    3                                                                     |      8  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Dilatation                           |                      3                                                   |      6  3.0|
      Thrombosis                           |                               X                                          |      2     |
      Endometrium, Cyst                    |                                                                          |      1     |
                                            __________________________________________________________________________|____________|
   Vagina                                  |                                                                          |   1        |
      Exudate                              |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |                               4                 2  3                     |     11  3.0|
      Myelofibrosis                        |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                           +              +               |   6        |
      Mediastinal, Angiectasis             |                                                                          |      1  3.0|
      Pancreatic, Angiectasis              |                                                          3               |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  3.0|
      Cyst                                 |                                                                          |      1     |
      Giant Cell                           |                                                                          |      1  2.0|
      Inflammation, Acute                  |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Congestion                           |                                        3                                 |      1  3.0|
      Giant Cell                           |       2                          2                                       |     10  2.2|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Depletion Lymphoid                   |                                                                          |      1  2.0|
      Fibrosis, Focal                      |                                                                          |      1  3.0|
      Hematopoietic Cell Proliferation     |                                                                          |      2  4.0|
      Necrosis, Focal                      |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +               |  68        |
      Depletion Lymphoid                   |                                                 4                        |      2  3.0|
      Lymphatic, Angiectasis               |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  25                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 6| 7| 7| 4| 4| 2| 7| 7| 7| 7| 5| 7| 6| 7|              |            |
                             DAY ON TEST   | 4| 6| 8| 4| 4| 4| 1| 4| 1| 6| 8| 8| 4| 4| 4| 4| 7| 4| 9| 1|              |            |
                                           | 4| 3| 2| 7| 7| 7| 9| 4| 3| 4| 8| 1| 7| 7| 7| 4| 9| 7| 9| 8|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|              |      A     |
    100 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 INTEGUMENTARY SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Galactocele                          |             X                          X                                 |      5     |
      Galactocele, Multiple                |          X                                                               |      1     |
      Lactation                            |             2     3  4  2     3     3  3  2  2     2  4  2               |     36  2.9|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Acanthosis                           |                                                                          |      1  3.0|
      Cyst Epithelial Inclusion            |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |                   4                 3  3     3                           |      9  3.1|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Compression                          |                                                       2                  |      6  3.3|
      Hemorrhage                           |                         4     1                          2               |      4  2.5|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      2  2.0|
      Peribronchial, Inflammation, Chronic |       2                          1                                       |     10  1.8|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Fungus                               | 4                       2                             3                  |      4  2.8|
      Inflammation, Acute                  |                         2                                                |      1  2.0|
      Inflammation, Chronic, Focal         |       2                          2                                       |     10  2.0|
      Inflammation, Chronic                |    2                       2                                             |     12  1.9|
      Metaplasia, Squamous                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Cataract                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cyst                                 |                                                                          |      1     |
      Glomerulosclerosis                   |                                                    4     2               |      2  3.0|
      Mineralization, Focal                |                                                                          |      5  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  26                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 6| 7| 7| 4| 4| 2| 7| 7| 7| 7| 5| 7| 6| 7|              |            |
                             DAY ON TEST   | 4| 6| 8| 4| 4| 4| 1| 4| 1| 6| 8| 8| 4| 4| 4| 4| 7| 4| 9| 1|              |            |
                                           | 4| 3| 2| 7| 7| 7| 9| 4| 3| 4| 8| 1| 7| 7| 7| 4| 9| 7| 9| 8|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|              |      A     |
    100 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Mineralization                       |                1  2     3     2     1     1  1                           |     22  1.6|
      Nephropathy                          | 2  2     1  3  2  1  2  1           2  3  1  1        3  1               |     49  1.9|
      Renal Tubule, Degeneration, Granular |                                                                          |      1  2.0|
      Renal Tubule, Pigmentation, Bile     |                   4                                                      |      6  2.5|
      Renal Tubule, Regeneration           |       1                          1                                       |      2  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +               |  64        |
      Hyperplasia, Focal                   |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  27                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 2| 4| 7| 4| 2| 5| 7| 7| 4| 4| 7| 7| 2| 4| 2| 7| 7| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 7| 8| 6| 4| 6| 8| 6| 4| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 8| 4| 4| 4| 4| 4|             
                                           | 5| 5| 1| 3| 2| 3| 1| 7| 2| 2| 3| 4| 2| 2| 2| 4| 1| 2| 2| 8| 2| 2| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                     3                                    |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                   X                                                      |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                               2                                          |             
      Angiectasis                          |                                     2                             2      |             
      Basophilic Focus                     |    X        X  X     X  X  X  X        X     X     X  X  X  X  X  X     X|             
      Clear Cell Focus                     |                                                                          |             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |                                                                          |             
      Granuloma                            |       1           1              2                                       |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Bile Duct, Hyperplasia               |                1              1              2                           |             
                                            __________________________________________________________________________|             
   Mesentery                               |                            +                       +                 +  +|             
      Fat, Necrosis                        |                            4                       4                 2  4|             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |       1                 2        2  4  2     3     2        2  1         |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Erosion                              |                                                                          |             
      Ulcer                                | 4                                                                        |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |                            2  2     2  3                 1  2     1     2|             
      Inflammation, Chronic, Focal         |                                           1                              |             
      Artery, Mineralization               |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  28                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 2| 4| 7| 4| 2| 5| 7| 7| 4| 4| 7| 7| 2| 4| 2| 7| 7| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 7| 8| 6| 4| 6| 8| 6| 4| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 8| 4| 4| 4| 4| 4|             
                                           | 5| 5| 1| 3| 2| 3| 1| 7| 2| 2| 3| 4| 2| 2| 2| 4| 1| 2| 2| 8| 2| 2| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Cytoplasmic Alteration, Focal        |                            2        4  4                                 |             
      Hyperplasia, Focal                   |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |    2        1           2                                                |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hypoplasia                           |                   3                                                      |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                             3            |             
      Pars Distalis, Cyst                  |    X  X                       X                                X     X   |             
      Pars Distalis, Hyperplasia, Focal    |    2                                4              2           4  2  2   |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                               2                             1     4  2   |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Dilatation                           |                                                    3                     |             
      Inflammation, Acute                  |                         3                          2                     |             
      Inflammation, Chronic, Focal         |                   1                       2     2                        |             
      Inflammation, Chronic                | 2              2                 2           2                           |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Cyst                                 |                            X                    X     X  X               |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Atrophy                              |                                                                          |             
      Dilatation                           |                   2           3           3     2     2                  |             
      Thrombosis                           |                                                                          |             
      Endometrium, Fibrosis                |                                                                          |             
      Endometrium, Hyperplasia, Cystic     |                                     2                                    |             
                                            __________________________________________________________________________|             
   Vagina                                  |                      +                                      +            |             
      Dilatation                           |                                                             3            |             
      Exudate                              |                      X                                                   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |    +                                                                     |             
      Hypochromasia                        |    X                                                                     |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2  3                       3        4                                3   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  29                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 2| 4| 7| 4| 2| 5| 7| 7| 4| 4| 7| 7| 2| 4| 2| 7| 7| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 7| 8| 6| 4| 6| 8| 6| 4| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 8| 4| 4| 4| 4| 4|             
                                           | 5| 5| 1| 3| 2| 3| 1| 7| 2| 2| 3| 4| 2| 2| 2| 4| 1| 2| 2| 8| 2| 2| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                        +                                 |             
      Lumbar, Hyperplasia                  |                                                                          |             
      Mediastinal, Angiectasis             |                                                                          |             
      Mediastinal, Congestion              |                                        3                                 |             
      Mediastinal, Hematopoietic Cell      |                                                                          |             
          Proliferation                    |                                                                          |             
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |             
      Pancreatic, Granuloma                |                                                                          |             
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Giant Cell                           |                                           2                              |             
      Infiltration Cellular, Plasma Cell   |    4                                                                     |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                        3                                 |             
      Giant Cell                           |       3           2                       3     3                        |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                        2                 2               |             
      Fibrosis, Focal                      |                                                                          |             
      Granuloma                            |                                                                          |             
      Hematopoietic Cell Proliferation     |    4                                                                     |             
      Infarct                              |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |    4                                                                     |             
      Hyperplasia                          |                                                             1            |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                          |             
      Lactation                            |    3                 4     2        2  2              3  4  3        4   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                                                          |             
      Hyperkeratosis                       |                                                                          |             
      Perivascular, Inflammation, Chronic  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                     3  4              X                  |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                             +            |             
      Ectopic Tissue                       |                                                             X            |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  30                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 2| 4| 7| 4| 2| 5| 7| 7| 4| 4| 7| 7| 2| 4| 2| 7| 7| 6| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 7| 8| 6| 4| 6| 8| 6| 4| 4| 6| 6| 4| 4| 8| 6| 8| 4| 4| 8| 4| 4| 4| 4| 4|             
                                           | 5| 5| 1| 3| 2| 3| 1| 7| 2| 2| 3| 4| 2| 2| 2| 4| 1| 2| 2| 8| 2| 2| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                      X                                   X               |             
      Hemorrhage                           | 3                                                                        |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                     1  2                                 |             
      Congestion                           |                                                                          |             
      Emphysema, Focal                     |                                                                          |             
      Hemorrhage, Focal                    |                                                                          |             
      Alveolar Epithelium, Metaplasia      |                                                                          |             
      Peribronchial, Inflammation, Chronic |       2           2                       2     2                        |             
      Pleura, Fibrosis, Focal              |                                     2                                    |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                                                                          |             
      Inflammation, Acute                  |                                                                         2|             
      Inflammation, Chronic, Focal         |       2           2                       2     2                        |             
      Inflammation, Chronic                | 3        2     2     2  2     2  2           2                           |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |    +                                                                     |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Mineralization, Focal                |                   1                                                      |             
      Mineralization                       |    2                       2           2           2  2     2  2  2      |             
      Nephropathy                          |    2     1  1        2  2  2  1  2  1  2              1     2  2  2     2|             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |                                                                          |             
      Renal Tubule, Regeneration           |                                                 1                        |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  31                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 4| 7| 2| 2| 4| 7| 6| 2| 7| 7| 7| 7| 4| 7| 2| 5| 7| 6| 7| 7| 7| 5| 2|             
                             DAY ON TEST   | 4| 3| 6| 4| 8| 8| 6| 4| 7| 8| 4| 4| 4| 4| 6| 4| 8| 4| 4| 3| 4| 3| 4| 8| 8|             
                                           | 2| 0| 3| 2| 8| 1| 6| 2| 5| 2| 2| 2| 2| 2| 4| 3| 2| 6| 3| 8| 3| 0| 3| 8| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Parasite Metazoan                    |                X                             3                           |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                      2                       4                           |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Parasite Metazoan                    |                X                                                         |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
      Parasite Metazoan                    |                                                                         X|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                                                                          |             
      Angiectasis                          |    3                                                              2      |             
      Basophilic Focus                     | X        X        X  X        X  X     X     X           X  X     X      |             
      Clear Cell Focus                     | X                                                                        |             
      Eosinophilic Focus                   |                                                             X            |             
      Fatty Change                         |    2                                                           4     2   |             
      Granuloma                            |                            1           2  2     1                        |             
      Hepatodiaphragmatic Nodule           |       X                             X                                    |             
      Bile Duct, Hyperplasia               |                1                          1                              |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                       +  +  +  +         |             
      Fat, Necrosis                        |                                                          2  3  4         |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |                      3        2              2     3     1  4            |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |    4                                                                     |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Erosion                              |    3              3                                            2         |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                  +                                       |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2        2           2              2  3                          2      |             
      Inflammation, Chronic, Focal         |                1           1                    1                        |             
      Artery, Mineralization               |                                                                      3   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |       4                                                                  |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  32                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 4| 7| 2| 2| 4| 7| 6| 2| 7| 7| 7| 7| 4| 7| 2| 5| 7| 6| 7| 7| 7| 5| 2|             
                             DAY ON TEST   | 4| 3| 6| 4| 8| 8| 6| 4| 7| 8| 4| 4| 4| 4| 6| 4| 8| 4| 4| 3| 4| 3| 4| 8| 8|             
                                           | 2| 0| 3| 2| 8| 1| 6| 2| 5| 2| 2| 2| 2| 2| 4| 3| 2| 6| 3| 8| 3| 0| 3| 8| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Cytoplasmic Alteration, Focal        | 3  3                          2  2                       2               |             
      Hyperplasia, Focal                   |                                                             4            |             
      Vacuolization Cytoplasmic            |                         4                                      3         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hypoplasia                           |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                           3                              |             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hyperplasia, Focal    |    3                    3                                                |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |    3  2                 1     4  1     1           1                     |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Dilatation                           |                                        3                                 |             
      Inflammation, Acute                  |                                                                   2      |             
      Inflammation, Chronic, Focal         |                2           2                    2                       1|             
      Inflammation, Chronic                | 3     2     2                 3                                          |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                      2                                                   |             
      Cyst                                 |    X           X                                                         |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Atrophy                              |                                                       2                  |             
      Dilatation                           |          3                 4                    3        3               |             
      Thrombosis                           |                                                                          |             
      Endometrium, Fibrosis                |                                              4                           |             
      Endometrium, Hyperplasia, Cystic     |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                         +                                                |             
      Dilatation                           |                                                                          |             
      Exudate                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
      Hypochromasia                        |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    4              4     3                          2  2  3     3     2   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  33                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 4| 7| 2| 2| 4| 7| 6| 2| 7| 7| 7| 7| 4| 7| 2| 5| 7| 6| 7| 7| 7| 5| 2|             
                             DAY ON TEST   | 4| 3| 6| 4| 8| 8| 6| 4| 7| 8| 4| 4| 4| 4| 6| 4| 8| 4| 4| 3| 4| 3| 4| 8| 8|             
                                           | 2| 0| 3| 2| 8| 1| 6| 2| 5| 2| 2| 2| 2| 2| 4| 3| 2| 6| 3| 8| 3| 0| 3| 8| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |    +                    +     +        +              +        +     +   |             
      Lumbar, Hyperplasia                  |                                                                      2   |             
      Mediastinal, Angiectasis             |                                                                          |             
      Mediastinal, Congestion              |                                                                          |             
      Mediastinal, Hematopoietic Cell      |                                                                          |             
          Proliferation                    |                                                                          |             
      Mediastinal, Lymphatic, Angiectasis  |                               4                                          |             
      Pancreatic, Granuloma                |                                                                          |             
      Pancreatic, Lymphatic, Angiectasis   |                                        3                                 |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             4                                                            |             
      Giant Cell                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Lymphatic, Angiectasis               |                                        3                                 |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
      Congestion                           |                      4                 4                                 |             
      Giant Cell                           |                2           3                                            3|             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                     2                                    |             
      Fibrosis, Focal                      |    3                                                                     |             
      Granuloma                            |                                                                          |             
      Hematopoietic Cell Proliferation     |                   4  3                                               4   |             
      Infarct                              |                                                    4                     |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
      Hyperplasia                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                          |             
      Lactation                            |    1              2  3                 2                    3  3     2   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                                                      4   |             
      Hyperkeratosis                       |                                                                      4   |             
      Perivascular, Inflammation, Chronic  |                               4                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |          3           4           2  3        2        2           2      |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
      Ectopic Tissue                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  34                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 4| 7| 2| 2| 4| 7| 6| 2| 7| 7| 7| 7| 4| 7| 2| 5| 7| 6| 7| 7| 7| 5| 2|             
                             DAY ON TEST   | 4| 3| 6| 4| 8| 8| 6| 4| 7| 8| 4| 4| 4| 4| 6| 4| 8| 4| 4| 3| 4| 3| 4| 8| 8|             
                                           | 2| 0| 3| 2| 8| 1| 6| 2| 5| 2| 2| 2| 2| 2| 4| 3| 2| 6| 3| 8| 3| 0| 3| 8| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|             
    500 PPM                                | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                      X                                                   |             
      Hemorrhage                           |                                                                1         |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                       +                  |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |             3                                                            |             
      Emphysema, Focal                     |                                     2                                    |             
      Hemorrhage, Focal                    |    3                                                                     |             
      Alveolar Epithelium, Metaplasia      | 3                                                                        |             
      Peribronchial, Inflammation, Chronic |                2           1                    2                       1|             
      Pleura, Fibrosis, Focal              |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                      4                                               4   |             
      Inflammation, Acute                  |                   2                                            2         |             
      Inflammation, Chronic, Focal         |                            2                    2                       2|             
      Inflammation, Chronic                |       2     3                             2                              |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Mineralization, Focal                |                1           1                    1                       1|             
      Mineralization                       | 2                 1           1  2  1              1     1           4   |             
      Nephropathy                          | 1  1  2  2           2        2  2  2  2     2              1  1  1      |             
      Renal Tubule, Degeneration, Granular |                                                       4                  |             
      Renal Tubule, Pigmentation, Bile     |                                                                3         |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  35                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 7| 7| 4| 7| 7| 2| 4| 7| 7| 7| 7| 5| 7| 7| 7| 7| 2| 6|              |            |
                             DAY ON TEST   | 4| 6| 4| 4| 6| 4| 4| 8| 6| 4| 4| 4| 4| 3| 4| 4| 4| 4| 8| 4|              |            |
                                           | 2| 4| 2| 2| 4| 3| 3| 2| 3| 3| 3| 3| 3| 9| 3| 3| 3| 3| 1| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|              |      A     |
    500 PPM                                | 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Parasite Metazoan                    |          3                    4     2     2                              |      7  2.8|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Parasite Metazoan                    |    4                                               2                     |      4  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Parasite Metazoan                    |                         2     2                 2                        |      5  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Parasite Metazoan                    |                                                                          |      1     |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis, Focal                   |                                                                          |      1  2.0|
      Angiectasis                          |                                                                          |      4  2.3|
      Basophilic Focus                     | X  X  X        X  X     X  X     X  X     X  X  X  X     X               |     41     |
      Clear Cell Focus                     | X                          X  X                                          |      4     |
      Eosinophilic Focus                   |                                                                          |      1     |
      Fatty Change                         |          2                             3                                 |      5  2.6|
      Granuloma                            |                                                                          |      7  1.4|
      Hepatodiaphragmatic Nodule           | X                                                  X     X               |      5     |
      Bile Duct, Hyperplasia               |                                                                          |      5  1.2|
                                            __________________________________________________________________________|____________|
   Mesentery                               |          +                                                               |   9        |
      Fat, Necrosis                        |          3                                                               |      8  3.3|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Acinus, Atrophy                      |          2                    3           4                              |     18  2.4|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |                                                          3               |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Ulcer                                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Cellular                   |                                                 2                        |      1  2.0|
      Erosion                              |                                                                          |      3  2.7|
      Ulcer                                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       | 2     2        1  1        4     1  1  3        1        2               |     24  1.9|
      Inflammation, Chronic, Focal         |                      1                                1                  |      6  1.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  36                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 7| 7| 4| 7| 7| 2| 4| 7| 7| 7| 7| 5| 7| 7| 7| 7| 2| 6|              |            |
                             DAY ON TEST   | 4| 6| 4| 4| 6| 4| 4| 8| 6| 4| 4| 4| 4| 3| 4| 4| 4| 4| 8| 4|              |            |
                                           | 2| 4| 2| 2| 4| 3| 3| 2| 3| 3| 3| 3| 3| 9| 3| 3| 3| 3| 1| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|              |      A     |
    500 PPM                                | 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
      Artery, Mineralization               |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  4.0|
      Cytoplasmic Alteration, Focal        |                                                                          |      8  2.8|
      Hyperplasia, Focal                   |       2                                                  3               |      3  3.0|
      Vacuolization Cytoplasmic            |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia, Focal                   |                                                                          |      3  1.7|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hypoplasia                           |                                                       2                  |      2  2.5|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +               |  65        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Pars Distalis, Angiectasis           |                                                                          |      2  3.0|
      Pars Distalis, Cyst                  |       X                       X                                          |      7     |
      Pars Distalis, Hyperplasia, Focal    |          2                 2           2  2                              |     12  2.5|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      C-Cell, Hyperplasia                  | 1                 1                    3                                 |     14  1.9|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cyst                                 |       X                                                                  |      1     |
      Dilatation                           | 3              3                          3                              |      5  3.0|
      Inflammation, Acute                  |                                                                          |      3  2.3|
      Inflammation, Chronic, Focal         |                      2                                1                  |      9  1.7|
      Inflammation, Chronic                | 2           2           3                                                |     11  2.3|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      1  2.0|
      Cyst                                 |                                                                          |      6     |
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                               3                                          |      1  3.0|
      Atrophy                              |                                                                          |      1  2.0|
      Dilatation                           |                      2                                                   |     10  2.7|
      Thrombosis                           |                                  X                                       |      1     |
      Endometrium, Fibrosis                |                                        2                                 |      2  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  37                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 7| 7| 4| 7| 7| 2| 4| 7| 7| 7| 7| 5| 7| 7| 7| 7| 2| 6|              |            |
                             DAY ON TEST   | 4| 6| 4| 4| 6| 4| 4| 8| 6| 4| 4| 4| 4| 3| 4| 4| 4| 4| 8| 4|              |            |
                                           | 2| 4| 2| 2| 4| 3| 3| 2| 3| 3| 3| 3| 3| 9| 3| 3| 3| 3| 1| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|              |      A     |
    500 PPM                                | 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Endometrium, Hyperplasia, Cystic     |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Vagina                                  |                                           +                              |   4        |
      Dilatation                           |                                                                          |      1  3.0|
      Exudate                              |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood                                   |                                                                          |   1        |
      Hypochromasia                        |                                                                          |      1     |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |          4                                3                              |     15  3.0|
      Myelofibrosis                        |                                                       2                  |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |    +     +        +                       +                              |  12        |
      Lumbar, Hyperplasia                  |                                                                          |      1  2.0|
      Mediastinal, Angiectasis             |          3                                                               |      1  3.0|
      Mediastinal, Congestion              |    4                                                                     |      2  3.5|
      Mediastinal, Hematopoietic Cell      |                                                                          |            |
          Proliferation                    |                                           4                              |      1  4.0|
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |      1  4.0|
      Pancreatic, Granuloma                |                   4                                                      |      1  4.0|
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  4.0|
      Giant Cell                           |                                                                          |      1  2.0|
      Infiltration Cellular, Plasma Cell   |                                                                          |      1  4.0|
      Lymphatic, Angiectasis               |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +               |  68        |
      Congestion                           |                                                                          |      3  3.7|
      Giant Cell                           |                      3                                                   |      8  2.8|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Lymphoid                   |                                     2     3        2                     |      6  2.2|
      Fibrosis, Focal                      |          2     4                                                         |      3  3.0|
      Granuloma                            |                                           4                              |      1  4.0|
      Hematopoietic Cell Proliferation     |                                                                          |      4  3.8|
      Infarct                              |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Lymphoid                   |                                                                          |      1  4.0|
      Hyperplasia                          |                                                                          |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  38                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 7| 7| 4| 7| 7| 2| 4| 7| 7| 7| 7| 5| 7| 7| 7| 7| 2| 6|              |            |
                             DAY ON TEST   | 4| 6| 4| 4| 6| 4| 4| 8| 6| 4| 4| 4| 4| 3| 4| 4| 4| 4| 8| 4|              |            |
                                           | 2| 4| 2| 2| 4| 3| 3| 2| 3| 3| 3| 3| 3| 9| 3| 3| 3| 3| 1| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|              |      A     |
    500 PPM                                | 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 INTEGUMENTARY SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  66        |
      Galactocele                          |                   X                             X                        |      2     |
      Lactation                            | 2        2     3           2  3  2  3        2  3  3     4               |     27  2.7|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Fibrosis                             |                                                                          |      1  4.0|
      Hyperkeratosis                       |                                                                          |      1  4.0|
      Perivascular, Inflammation, Chronic  |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |                                     2        4                           |     12  2.8|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
      Ectopic Tissue                       |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Compression                          | 2                                                                        |      4  2.0|
      Hemorrhage                           |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      2  1.5|
      Congestion                           |                                                                          |      1  3.0|
      Emphysema, Focal                     |                                                                          |      1  2.0|
      Hemorrhage, Focal                    |                                                                          |      1  3.0|
      Alveolar Epithelium, Metaplasia      |                                                                          |      1  3.0|
      Peribronchial, Inflammation, Chronic |                      2                                                   |      9  1.8|
      Pleura, Fibrosis, Focal              |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Fungus                               |                                     2                                    |      3  3.3|
      Inflammation, Acute                  |             3                                            2               |      5  2.2|
      Inflammation, Chronic, Focal         |                      2                                2                  |      9  2.0|
      Inflammation, Chronic                |    2  4  2  3           2                                                |     16  2.3|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  39                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 7| 7| 4| 7| 7| 2| 4| 7| 7| 7| 7| 5| 7| 7| 7| 7| 2| 6|              |            |
                             DAY ON TEST   | 4| 6| 4| 4| 6| 4| 4| 8| 6| 4| 4| 4| 4| 3| 4| 4| 4| 4| 8| 4|              |            |
                                           | 2| 4| 2| 2| 4| 3| 3| 2| 3| 3| 3| 3| 3| 9| 3| 3| 3| 3| 1| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|              |      A     |
    500 PPM                                | 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Cyst                                 |                                              X                           |      1     |
      Mineralization, Focal                |                      1                                1                  |      7  1.0|
      Mineralization                       |       2                                   2        1     2               |     20  1.8|
      Nephropathy                          | 3  2     2  1  2  2        1        2     1  2           2               |     39  1.7|
      Renal Tubule, Degeneration, Granular |                                                                          |      1  4.0|
      Renal Tubule, Pigmentation, Bile     |                                                                          |      1  3.0|
      Renal Tubule, Regeneration           |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  40                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 2| 4| 4| 7| 2| 4| 7| 7| 7| 7| 7| 7| 7| 4| 4| 7| 7| 7| 7| 4| 4| 7| 7| 7|             
                             DAY ON TEST   | 6| 8| 6| 0| 4| 8| 4| 4| 4| 4| 4| 4| 4| 4| 6| 6| 3| 3| 3| 3| 6| 6| 4| 3| 4|             
                                           | 3| 2| 3| 4| 1| 1| 2| 1| 1| 1| 1| 1| 1| 1| 3| 3| 7| 7| 7| 7| 4| 4| 1| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                 3                        |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                         2|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    | 3                                                           4  2         |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                                                          |             
      Parasite Metazoan                    |                         2  2              3  3     3                     |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                        2                          2      |             
      Basophilic Focus                     | X     X     X  X     X  X  X  X  X  X  X  X  X  X  X  X  X  X     X  X  X|             
      Clear Cell Focus                     |                            X  X                    X                 X   |             
      Fatty Change                         |                   3  1  2                             1                  |             
      Granuloma                            |    3  2                                   2              2               |             
      Hepatodiaphragmatic Nodule           |             X                                         X                  |             
      Hepatodiaphragmatic Nodule, Multiple |                                                                          |             
      Mineralization, Focal                |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Bile Duct, Hyperplasia               | 1                                                                        |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                        +                                 |             
      Accessory Spleen                     |                                                                          |             
      Fat, Necrosis                        |                                        3                                 |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
      Acinus, Atrophy                      |    2  2     2              3                                            3|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                                                                          |             
      Diverticulum                         |                                                       3                  |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Edema, Focal                         |                                                                          |             
      Erosion                              |          4                                                               |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                     +                                    |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |             1                          2        2  2  2  2        3  2  4|             
      Dilatation                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  41                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 2| 4| 4| 7| 2| 4| 7| 7| 7| 7| 7| 7| 7| 4| 4| 7| 7| 7| 7| 4| 4| 7| 7| 7|             
                             DAY ON TEST   | 6| 8| 6| 0| 4| 8| 4| 4| 4| 4| 4| 4| 4| 4| 6| 6| 3| 3| 3| 3| 6| 6| 4| 3| 4|             
                                           | 3| 2| 3| 4| 1| 1| 2| 1| 1| 1| 1| 1| 1| 1| 3| 3| 7| 7| 7| 7| 4| 4| 1| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |    1                                                                     |             
      Mineralization                       |                                                                          |             
      Myocardium, Inflammation, Chronic,   |                                                                          |             
           Focal                           |                                                                1         |             
      Perivascular, Inflammation           |                               3                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +|             
      Atrophy                              |                                                                          |             
      Cytoplasmic Alteration, Focal        |                            2                                             |             
      Mineralization, Focal                |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                     3                                2   |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hypoplasia                           |                2                                                         |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  M  +  +  M  M  M  +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                2         |             
      Pars Distalis, Cyst                  |                   X              X                 X                     |             
      Pars Distalis, Hyperplasia, Focal    |                      3  1           3           3     2           2      |             
      Pars Distalis, Hyperplasia           |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
      C-Cell, Hyperplasia                  |             3           2  1  2     1                             2      |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |             X              X                                             |             
      Dilatation                           |                      3  3     3                    2                     |             
      Inflammation, Acute                  |                                  3     2                                 |             
      Inflammation, Chronic, Focal         |    2           3                                                         |             
      Inflammation, Chronic                | 1     2           2           2           2  1                 2         |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                          3               |             
      Atrophy                              |                                                                          |             
      Cyst                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                       3                  |             
      Atrophy                              |                   2                                                      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  42                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 2| 4| 4| 7| 2| 4| 7| 7| 7| 7| 7| 7| 7| 4| 4| 7| 7| 7| 7| 4| 4| 7| 7| 7|             
                             DAY ON TEST   | 6| 8| 6| 0| 4| 8| 4| 4| 4| 4| 4| 4| 4| 4| 6| 6| 3| 3| 3| 3| 6| 6| 4| 3| 4|             
                                           | 3| 2| 3| 4| 1| 1| 2| 1| 1| 1| 1| 1| 1| 1| 3| 3| 7| 7| 7| 7| 4| 4| 1| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Cyst                                 |                            X                                             |             
      Dilatation                           |                               3     3                                    |             
      Endometrium, Cyst                    |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
      Bacterium                            |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |          2                          2                                   1|             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                +                                                         |             
      Inguinal, Congestion                 |                                                                          |             
      Lumbar, Congestion                   |                                                                          |             
      Mediastinal, Congestion              |                                                                          |             
      Pancreatic, Angiectasis              |                                                                          |             
      Pancreatic, Giant Cell               |                3                                                         |             
      Pancreatic, Infiltration Cellular,   |                                                                          |             
           Histiocyte                      |                                                                          |             
      Pancreatic, Pigmentation, Hemosiderin|                2                                                         |             
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                                          3               |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Lymphatic, Angiectasis               |                                     3                                    |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |    2           1                                                         |             
      Granuloma                            |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                               2                                   2      |             
      Fibrosis, Focal                      |                                                                          |             
      Hematopoietic Cell Proliferation     |          2        4                                                      |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Cyst                                 |                                        X                       X  X      |             
      Depletion Lymphoid                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                                                          |             
      Lactation                            |             3                 2  4  2  3        2  3  4           2      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  43                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 2| 4| 4| 7| 2| 4| 7| 7| 7| 7| 7| 7| 7| 4| 4| 7| 7| 7| 7| 4| 4| 7| 7| 7|             
                             DAY ON TEST   | 6| 8| 6| 0| 4| 8| 4| 4| 4| 4| 4| 4| 4| 4| 6| 6| 3| 3| 3| 3| 6| 6| 4| 3| 4|             
                                           | 3| 2| 3| 4| 1| 1| 2| 1| 1| 1| 1| 1| 1| 1| 3| 3| 7| 7| 7| 7| 4| 4| 1| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                     4  3                                 |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Compression                          |                                                                      4   |             
      Hemorrhage                           |          2                                                               |             
      Capillary, Inflammation, Chronic     |                                                             2            |             
      Choroid Plexus, Inflammation, Chronic|    2                                                                     |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization, Focal                |                                                                          |             
      Alveolar Epithelium, Metaplasia      |                                                                          |             
      Peribronchial, Inflammation, Chronic |    2           2                                                         |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |       4                                                                  |             
      Inflammation, Acute                  |       3                       2                                      3   |             
      Inflammation, Chronic, Focal         |    3           2                                                         |             
      Inflammation, Chronic                |          1        1                       2  2     3     3  2  2  2      |             
      Metaplasia, Squamous                 |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cataract                             |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Bacterium                            |                                                                          |             
      Cyst                                 |                                                                          |             
      Glomerulosclerosis                   |                                                                          |             
      Mineralization                       |                      1  1  1  1  2  2                    1               |             
      Nephropathy                          | 1           2     1     2  1        2  1        1  1  1     1  1  2  4   |             
      Pigmentation                         |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  44                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 2| 4| 4| 7| 2| 4| 7| 7| 7| 7| 7| 7| 7| 4| 4| 7| 7| 7| 7| 4| 4| 7| 7| 7|             
                             DAY ON TEST   | 6| 8| 6| 0| 4| 8| 4| 4| 4| 4| 4| 4| 4| 4| 6| 6| 3| 3| 3| 3| 6| 6| 4| 3| 4|             
                                           | 3| 2| 3| 4| 1| 1| 2| 1| 1| 1| 1| 1| 1| 1| 3| 3| 7| 7| 7| 7| 4| 4| 1| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Inflammation, Chronic, Focal         |                                                             2            |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  45                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 7| 4| 4| 2| 5| 2| 7| 6| 2| 7| 7| 2| 7| 2| 2| 4| 7| 5| 2| 7|             
                             DAY ON TEST   | 4| 4| 4| 4| 4| 4| 6| 6| 8| 9| 8| 4| 5| 8| 4| 4| 8| 4| 8| 8| 6| 3| 5| 8| 4|             
                                           | 1| 1| 1| 1| 1| 2| 3| 3| 1| 1| 2| 2| 8| 2| 2| 2| 1| 1| 2| 2| 4| 8| 9| 1| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                               X                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                    4     X  4            |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                                                2         |             
      Parasite Metazoan                    |          3                       3                       X               |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                            2                                   4         |             
      Basophilic Focus                     | X  X     X  X        X     X     X           X     X     X  X  X  X     X|             
      Clear Cell Focus                     |    X           X                             X                          X|             
      Fatty Change                         |                                                                1  1      |             
      Granuloma                            |                3                       1                                2|             
      Hepatodiaphragmatic Nodule           |          X                       X                                       |             
      Hepatodiaphragmatic Nodule, Multiple |                                                                          |             
      Mineralization, Focal                |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Bile Duct, Hyperplasia               |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               | +                                                                        |             
      Accessory Spleen                     |                                                                          |             
      Fat, Necrosis                        | 4                                                                        |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                        2              2                  |             
      Acinus, Atrophy                      | 3              3                    2              3                     |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                                                                          |             
      Diverticulum                         |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                         2|             
      Edema, Focal                         |                                                                          |             
      Erosion                              |                                     4                                    |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  3     2     2                 1  1        3                 2        2|             
      Dilatation                           |       2                                                                  |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  46                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 7| 4| 4| 2| 5| 2| 7| 6| 2| 7| 7| 2| 7| 2| 2| 4| 7| 5| 2| 7|             
                             DAY ON TEST   | 4| 4| 4| 4| 4| 4| 6| 6| 8| 9| 8| 4| 5| 8| 4| 4| 8| 4| 8| 8| 6| 3| 5| 8| 4|             
                                           | 1| 1| 1| 1| 1| 2| 3| 3| 1| 1| 2| 2| 8| 2| 2| 2| 1| 1| 2| 2| 4| 8| 9| 1| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic, Focal         |                         1     1        1                                 |             
      Mineralization                       |                                                                          |             
      Myocardium, Inflammation, Chronic,   |                                                                          |             
           Focal                           |                                                                          |             
      Perivascular, Inflammation           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                     2                                    |             
      Cytoplasmic Alteration, Focal        |       2                                                                  |             
      Mineralization, Focal                |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
      Necrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hypoplasia                           |                               1                 1        1               |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Pars Distalis, Angiectasis           |                                           4                              |             
      Pars Distalis, Cyst                  |       X           X                 X  X                          X      |             
      Pars Distalis, Hyperplasia, Focal    |                                           2           1                  |             
      Pars Distalis, Hyperplasia           |                                                             1            |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                       1                  |             
      C-Cell, Hyperplasia                  | 1        1                                                     2         |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                 X                        |             
      Dilatation                           | 3  3     2  3                                                            |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         |                               2        2              2  2           1   |             
      Inflammation, Chronic                |                   2  2                                      2            |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Atrophy                              |                                     3                                    |             
      Cyst                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Atrophy                              |                                     3                                    |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  47                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 7| 4| 4| 2| 5| 2| 7| 6| 2| 7| 7| 2| 7| 2| 2| 4| 7| 5| 2| 7|             
                             DAY ON TEST   | 4| 4| 4| 4| 4| 4| 6| 6| 8| 9| 8| 4| 5| 8| 4| 4| 8| 4| 8| 8| 6| 3| 5| 8| 4|             
                                           | 1| 1| 1| 1| 1| 2| 3| 3| 1| 1| 2| 2| 8| 2| 2| 2| 1| 1| 2| 2| 4| 8| 9| 1| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Cyst                                 |                                           X                              |             
      Dilatation                           |                                  3        3        3  4                  |             
      Endometrium, Cyst                    |                                                                          |             
                                            __________________________________________________________________________|             
   Vagina                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
      Bacterium                            |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |       2                             2                          3  3      |             
      Myelofibrosis                        |                                     2                                    |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                     +        +     +     +     +         |             
      Inguinal, Congestion                 |                                     4                                    |             
      Lumbar, Congestion                   |                                     3                                    |             
      Mediastinal, Congestion              |                                              4                           |             
      Pancreatic, Angiectasis              |                                     4                                    |             
      Pancreatic, Giant Cell               |                                                          4               |             
      Pancreatic, Infiltration Cellular,   |                                                                          |             
           Histiocyte                      |                                              3                           |             
      Pancreatic, Pigmentation, Hemosiderin|                                                          2               |             
      Pancreatic, Lymphatic, Angiectasis   |                                                    3           4         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Congestion                           |                               2              2     3                     |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Lymphatic, Angiectasis               |                                     3                                    |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                     4                             3      |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |                         2     2        2        3     2  1           2   |             
      Granuloma                            |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |          3                                1  3                 2        2|             
      Fibrosis, Focal                      |          3                                                               |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  M  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Cyst                                 |                                                                          |             
      Depletion Lymphoid                   |                                     4                                    |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Galactocele                          |                                              X                           |             
      Lactation                            | 2        2  2                    3        3        3           2         |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  48                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 7| 4| 4| 2| 5| 2| 7| 6| 2| 7| 7| 2| 7| 2| 2| 4| 7| 5| 2| 7|             
                             DAY ON TEST   | 4| 4| 4| 4| 4| 4| 6| 6| 8| 9| 8| 4| 5| 8| 4| 4| 8| 4| 8| 8| 6| 3| 5| 8| 4|             
                                           | 1| 1| 1| 1| 1| 2| 3| 3| 1| 1| 2| 2| 8| 2| 2| 2| 1| 1| 2| 2| 4| 8| 9| 1| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |       4        2                                                        4|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Compression                          |                            4     2                 3                     |             
      Hemorrhage                           |       2                             4                                    |             
      Capillary, Inflammation, Chronic     |                                                                          |             
      Choroid Plexus, Inflammation, Chronic|                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization, Focal                |                                                                          |             
      Alveolar Epithelium, Metaplasia      |                                                                          |             
      Peribronchial, Inflammation, Chronic |                         2     2        2        2     2  2           2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                                  3                             4         |             
      Inflammation, Acute                  | 2  3     2                 2                                             |             
      Inflammation, Chronic, Focal         |                               2        2              2  2           2   |             
      Inflammation, Chronic                |                   2  2                                      2            |             
      Metaplasia, Squamous                 |                                                          3               |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cataract                             |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Bacterium                            |                                                                          |             
      Cyst                                 |       X                                                                  |             
      Glomerulosclerosis                   |                                     4                                    |             
      Mineralization                       |                                     1        1     2                     |             
      Nephropathy                          | 1     2  1     2  1  1     2     2        2  2     1        1  2        2|             
      Pigmentation                         |                                  3                                       |             
      Renal Tubule, Pigmentation, Bile     |                                     3                                    |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  49                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 7| 4| 4| 2| 5| 2| 7| 6| 2| 7| 7| 2| 7| 2| 2| 4| 7| 5| 2| 7|             
                             DAY ON TEST   | 4| 4| 4| 4| 4| 4| 6| 6| 8| 9| 8| 4| 5| 8| 4| 4| 8| 4| 8| 8| 6| 3| 5| 8| 4|             
                                           | 1| 1| 1| 1| 1| 2| 3| 3| 1| 1| 2| 2| 8| 2| 2| 2| 1| 1| 2| 2| 4| 8| 9| 1| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|             
    1000 PPM                               | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Renal Tubule, Regeneration           |                                                          1           1   |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                     4                                    |             
      Inflammation, Chronic, Focal         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  50                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 6| 7| 7| 7| 7| 5| 7| 7| 6| 7| 7| 6| 7| 2| 6| 7| 7| 7|              |            |
                             DAY ON TEST   | 4| 6| 1| 4| 4| 4| 4| 3| 4| 1| 3| 4| 4| 7| 4| 8| 6| 4| 4| 4|              |            |
                                           | 1| 4| 9| 2| 2| 1| 2| 0| 1| 4| 7| 1| 1| 6| 1| 1| 9| 1| 1| 1|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|              |      A     |
    1000 PPM                               | 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Angiectasis                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Parasite Metazoan                    |                         2              3                                 |      4  2.3|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Parasite Metazoan                    |                                                                          |      6  3.4|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +               |  68        |
      Inflammation, Chronic                |                                                                          |      1  2.0|
      Parasite Metazoan                    |                                                                          |      8  2.7|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +               |  68        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +               |  68        |
      Abscess                              |                                                 2                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      4  2.5|
      Basophilic Focus                     | X     X  X  X  X  X     X        X  X  X  X           X  X               |     48     |
      Clear Cell Focus                     |                         X        X                                       |     10     |
      Fatty Change                         | 1                                                                        |      7  1.4|
      Granuloma                            |                                                    2                     |      8  2.1|
      Hepatodiaphragmatic Nodule           |                      X  X                                                |      6     |
      Hepatodiaphragmatic Nodule, Multiple |                   X                                                      |      1     |
      Mineralization, Focal                |                      3                                                   |      1  3.0|
      Necrosis, Focal                      |                                                 2                        |      1  2.0|
      Bile Duct, Hyperplasia               |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                            +                                             |   3        |
      Accessory Spleen                     |                            X                                             |      1     |
      Fat, Necrosis                        |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Inflammation, Chronic, Focal         |                                                                          |      2  2.0|
      Acinus, Atrophy                      |             2  4     2           4                                       |     13  2.7|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Acanthosis                           |                      3                                                   |      1  3.0|
      Diverticulum                         |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Cellular                   |                                                                          |      1  2.0|
      Edema, Focal                         |                               2                                          |      1  2.0|
      Erosion                              |       2              4                          4                        |      5  3.6|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  51                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 6| 7| 7| 7| 7| 5| 7| 7| 6| 7| 7| 6| 7| 2| 6| 7| 7| 7|              |            |
                             DAY ON TEST   | 4| 6| 1| 4| 4| 4| 4| 3| 4| 1| 3| 4| 4| 7| 4| 8| 6| 4| 4| 4|              |            |
                                           | 1| 4| 9| 2| 2| 1| 2| 0| 1| 4| 7| 1| 1| 6| 1| 1| 9| 1| 1| 1|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|              |      A     |
    1000 PPM                               | 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       | 2        3              2        3     4  2     2  2                     |     26  2.2|
      Dilatation                           |                                                                          |      1  2.0|
      Inflammation, Chronic, Focal         |                                                                          |      4  1.0|
      Mineralization                       |                      1                                                   |      1  1.0|
      Myocardium, Inflammation, Chronic,   |                                                                          |            |
           Focal                           |                                                                          |      1  1.0|
      Perivascular, Inflammation           |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Atrophy                              |                                                                          |      1  2.0|
      Cytoplasmic Alteration, Focal        |                                           2                              |      3  2.0|
      Mineralization, Focal                |                      3                                                   |      1  3.0|
      Vacuolization Cytoplasmic            |                               2                 3                        |      2  2.5|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia, Focal                   |                                                                          |      2  2.5|
      Necrosis                             |                                                 3                        |      1  3.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hypoplasia                           |                                                                          |      4  1.3|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +               |  61        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Pars Distalis, Angiectasis           |                                                                          |      2  3.0|
      Pars Distalis, Cyst                  |                                                                          |      8     |
      Pars Distalis, Hyperplasia, Focal    |                   2           3  3                                       |     11  2.3|
      Pars Distalis, Hyperplasia           |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Inflammation, Chronic, Focal         |                                                                          |      1  1.0|
      C-Cell, Hyperplasia                  |                   1                       1              1               |     12  1.5|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cyst                                 |                                                                          |      3     |
      Dilatation                           |                         3                                                |      9  2.8|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  52                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 6| 7| 7| 7| 7| 5| 7| 7| 6| 7| 7| 6| 7| 2| 6| 7| 7| 7|              |            |
                             DAY ON TEST   | 4| 6| 1| 4| 4| 4| 4| 3| 4| 1| 3| 4| 4| 7| 4| 8| 6| 4| 4| 4|              |            |
                                           | 1| 4| 9| 2| 2| 1| 2| 0| 1| 4| 7| 1| 1| 6| 1| 1| 9| 1| 1| 1|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|              |      A     |
    1000 PPM                               | 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Acute                  |                                                                          |      2  2.5|
      Inflammation, Chronic, Focal         |                                              2                           |      8  2.0|
      Inflammation, Chronic                |    2                                                                     |     11  1.8|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      1  3.0|
      Atrophy                              |                                                                          |      1  3.0|
      Cyst                                 | X                             X                                          |      2     |
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      1  3.0|
      Atrophy                              |                                                                          |      2  2.5|
      Cyst                                 |                                                                          |      2     |
      Dilatation                           |                                                                          |      6  3.2|
      Endometrium, Cyst                    |                                                          X               |      1     |
                                            __________________________________________________________________________|____________|
   Vagina                                  |                                     +                                    |   1        |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood                                   |                      +                                                   |   1        |
      Bacterium                            |                      X                                                   |      1     |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |       3              2     4  3        3                                 |     12  2.5|
      Myelofibrosis                        |                                                 4                        |      2  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                            +           +                                 |   8        |
      Inguinal, Congestion                 |                                                                          |      1  4.0|
      Lumbar, Congestion                   |                                                                          |      1  3.0|
      Mediastinal, Congestion              |                                                                          |      1  4.0|
      Pancreatic, Angiectasis              |                                                                          |      1  4.0|
      Pancreatic, Giant Cell               |                                                                          |      2  3.5|
      Pancreatic, Infiltration Cellular,   |                                                                          |            |
           Histiocyte                      |                                                                          |      1  3.0|
      Pancreatic, Pigmentation, Hemosiderin|                                                                          |      2  2.0|
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Congestion                           |                                                                          |      3  2.3|
      Infiltration Cellular, Plasma Cell   |                                                                          |      1  3.0|
      Infiltration Cellular, Histiocyte    |       4                                                                  |      1  4.0|
      Lymphatic, Angiectasis               |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                3                    4                                    |      4  3.5|
      Depletion Lymphoid                   |       4                                                                  |      1  4.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  53                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 6| 7| 7| 7| 7| 5| 7| 7| 6| 7| 7| 6| 7| 2| 6| 7| 7| 7|              |            |
                             DAY ON TEST   | 4| 6| 1| 4| 4| 4| 4| 3| 4| 1| 3| 4| 4| 7| 4| 8| 6| 4| 4| 4|              |            |
                                           | 1| 4| 9| 2| 2| 1| 2| 0| 1| 4| 7| 1| 1| 6| 1| 1| 9| 1| 1| 1|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|              |      A     |
    1000 PPM                               | 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Giant Cell                           |                                              1                           |     10  1.8|
      Granuloma                            | 4                                                                        |      1  4.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Lymphoid                   |                         1                             2                  |      9  2.0|
      Fibrosis, Focal                      |                                                                          |      1  3.0|
      Hematopoietic Cell Proliferation     |       3                                                                  |      3  3.0|
      Capsule, Fibrosis                    |             2                                                            |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  65        |
      Cyst                                 |                                                                          |      3     |
      Depletion Lymphoid                   |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Galactocele                          |                                                                          |      1     |
      Lactation                            | 2           2  3  2           3        2  2        2     2               |     25  2.5|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |       3                       3     3                                    |      8  3.3|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Abscess                              |                                                 2                        |      1  2.0|
      Compression                          |                                                                          |      4  3.3|
      Hemorrhage                           |                               4                                          |      4  3.0|
      Capillary, Inflammation, Chronic     |    2                                                                     |      2  2.0|
      Choroid Plexus, Inflammation, Chronic|                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                               +                                          |   1        |
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                               +                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Mineralization, Focal                |                      4                                                   |      1  4.0|
      Alveolar Epithelium, Metaplasia      |                                           4                              |      1  4.0|
      Peribronchial, Inflammation, Chronic |                                              2                           |     10  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Fungus                               |                                                                          |      3  3.7|
      Inflammation, Acute                  |             2                 3                          2               |     10  2.4|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  54                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 6| 7| 7| 7| 7| 5| 7| 7| 6| 7| 7| 6| 7| 2| 6| 7| 7| 7|              |            |
                             DAY ON TEST   | 4| 6| 1| 4| 4| 4| 4| 3| 4| 1| 3| 4| 4| 7| 4| 8| 6| 4| 4| 4|              |            |
                                           | 1| 4| 9| 2| 2| 1| 2| 0| 1| 4| 7| 1| 1| 6| 1| 1| 9| 1| 1| 1|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS FEMALE                 | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5|              |      A     |
    1000 PPM                               | 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|              |      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|              |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic, Focal         |                                              2                           |      8  2.1|
      Inflammation, Chronic                |    3                                               3                     |     14  2.1|
      Metaplasia, Squamous                 |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     | +                             +                                          |   2        |
      Cataract                             | 2                                                                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Harderian Gland                         | +                                                                        |   2        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Abscess                              |                                                 3                        |      1  3.0|
      Bacterium                            |                      X                                                   |      1     |
      Cyst                                 |                                                                          |      1     |
      Glomerulosclerosis                   |                                                                          |      1  4.0|
      Mineralization                       | 2        1  1     2        1  1  1        1           2  1               |     20  1.3|
      Nephropathy                          | 1  1        2  2  1        1  1  1  1  1           1  2                  |     40  1.5|
      Pigmentation                         |                                                                          |      1  3.0|
      Renal Tubule, Pigmentation, Bile     |                                                 2                        |      2  2.5|
      Renal Tubule, Regeneration           |                                                                          |      2  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Hemorrhage                           |                      4                                                   |      2  4.0|
      Inflammation, Chronic, Focal         |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  55                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 6| 4| 7| 5| 4| 7| 2| 7| 6| 7| 5| 7| 7| 7| 4| 2| 2| 2| 3| 4| 6| 7| 7|             
                             DAY ON TEST   | 5| 3| 3| 6| 3| 2| 6| 3| 7| 3| 9| 1| 6| 1| 3| 3| 6| 7| 7| 7| 0| 6| 3| 3| 3|             
                                           | 9| 2| 2| 3| 6| 4| 2| 6| 6| 6| 5| 5| 6| 7| 6| 6| 2| 6| 6| 5| 4| 3| 9| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |       2                 X  4                 4        X              X   |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |       2        3        X                       4  X  X                  |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |             4                                                            |             
      Parasite Metazoan                    |                            2                                         X   |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |             3        4                                                   |             
      Basophilic Focus                     |       X     X  X  X  X     X  X  X  X     X  X                    X  X  X|             
      Clear Cell Focus                     |                               X              X                           |             
      Cyst                                 |                                                                          |             
      Developmental Malformation           |                                                                         X|             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |    2                 2                 4                                 |             
      Fibrosis, Focal                      |                                        3                                 |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Necrosis, Focal                      |                                           2                              |             
      Proliferation                        |                3                                                         |             
      Bile Duct, Hyperplasia               |                   2  3                 4        2                       4|             
      Lymphatic, Angiectasis, Focal        |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +                                                  +        +      |             
      Accessory Spleen                     |                                                                          |             
      Fat, Hemorrhage                      |                                                                   4      |             
      Fat, Necrosis                        |                                                          3               |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |          3                 3  2        4  2                       1     3|             
      Acinus, Hyperplasia, Focal           |                                                                          |             
      Vein, Thrombosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                     2                                    |             
      Thrombosis                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                         3|             
      Ulcer                                | 2                                4                                       |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                        4                          1      |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Mucosa, Inflammation, Acute          |                                           3                              |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  56                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 6| 4| 7| 5| 4| 7| 2| 7| 6| 7| 5| 7| 7| 7| 4| 2| 2| 2| 3| 4| 6| 7| 7|             
                             DAY ON TEST   | 5| 3| 3| 6| 3| 2| 6| 3| 7| 3| 9| 1| 6| 1| 3| 3| 6| 7| 7| 7| 0| 6| 3| 3| 3|             
                                           | 9| 2| 2| 3| 6| 4| 2| 6| 6| 6| 5| 5| 6| 7| 6| 6| 2| 6| 6| 5| 4| 3| 9| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  3  2  1  2  4     4     1  2  2  2  3  2  4  2     2           3  2  3|             
      Inflammation, Chronic, Focal         |                         1                                2               |             
      Mineralization                       |             2                                                            |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Dilatation                   |                               4                                          |             
      Atrium, Thrombosis                   |                      X                 X                                 |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                                                          |             
      Cytoplasmic Alteration               |                                                                2         |             
      Hypertrophy                          | 3                                                                        |             
      Vacuolization Cytoplasmic            |                                  3                                       |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                        4                                 |             
      Hyperplasia, Focal                   |                               1                                         2|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                     2     2                             2|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectopic Thymus                       |                                                                          |             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hyperplasia, Focal    |                3                             3                       2   |             
      Pars Intermedia, Cyst                |                                                                X         |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |          4                 3                                            2|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                         2|             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Cyst                                 |       X                                                                  |             
      Ectasia                              |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Inflammation, Chronic, Focal         |                                                    2  2  2               |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  57                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 6| 4| 7| 5| 4| 7| 2| 7| 6| 7| 5| 7| 7| 7| 4| 2| 2| 2| 3| 4| 6| 7| 7|             
                             DAY ON TEST   | 5| 3| 3| 6| 3| 2| 6| 3| 7| 3| 9| 1| 6| 1| 3| 3| 6| 7| 7| 7| 0| 6| 3| 3| 3|             
                                           | 9| 2| 2| 3| 6| 4| 2| 6| 6| 6| 5| 5| 6| 7| 6| 6| 2| 6| 6| 5| 4| 3| 9| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic                | 1        1        2                       3     2           3  2         |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    2                 3     3           3  3                       2  2   |             
      Dilatation                           |                                                                          |             
      Inflammation, Acute                  |                                  3                                       |             
      Inflammation, Chronic                |                                                 4                        |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    4  3     3        4     4     4     4  4  3                    4  4  4|             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |                3                                         3               |             
      Interstitial Cell, Hyperplasia       |                                     3                                    |             
      Seminiferous Tubule, Atrophy         |             4                                                            |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |             2  4     4           3        3                       4  4  4|             
      Myelofibrosis                        |    4                                                                     |             
                                            __________________________________________________________________________|             
   Lymph Node                              |             +           +              +                          +  +   |             
      Mediastinal, Congestion              |                         3                                                |             
      Mediastinal, Lymphatic, Angiectasis  |                                                                   3      |             
      Pancreatic, Lymphatic, Angiectasis   |             4                                                            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |             3                                                            |             
      Congestion                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                           4                              |             
      Lymphatic, Angiectasis               |                      3                                                   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |             4                                                            |             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                             3            |             
      Giant Cell                           |                                                       2  2               |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                            4                                             |             
      Depletion Lymphoid                   |                               4     2                       2            |             
      Fibrosis                             |                      4                    4                          2  3|             
      Hematopoietic Cell Proliferation     |                4                 4                                3      |             
      Hypertrophy                          |    3                                                                     |             
      Infarct                              |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Thrombosis                           |             X                                                            |             
      Capsule, Congestion, Focal           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  58                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 6| 4| 7| 5| 4| 7| 2| 7| 6| 7| 5| 7| 7| 7| 4| 2| 2| 2| 3| 4| 6| 7| 7|             
                             DAY ON TEST   | 5| 3| 3| 6| 3| 2| 6| 3| 7| 3| 9| 1| 6| 1| 3| 3| 6| 7| 7| 7| 0| 6| 3| 3| 3|             
                                           | 9| 2| 2| 3| 6| 4| 2| 6| 6| 6| 5| 5| 6| 7| 6| 6| 2| 6| 6| 5| 4| 3| 9| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | M  +  +  +  +  M  +  M  +  +  +  M  +  +  +  M  +  +  +  +  +  +  M  +  +|             
      Depletion Lymphoid                   |                                                             2            |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  M  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  M|             
      Lactation                            |             1        4           2  4                                2   |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst Epithelial Inclusion            |    X                                                                     |             
      Fibrosis, Focal                      |                                                                          |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Callus                               |                                                                          |             
      Hyperostosis                         |             2                 2                                          |             
      Proliferation                        |    3                                                                     |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |       +                                                                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                     4                                    |             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
      Hemorrhage, Focal                    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                               3     3                                    |             
      Hemorrhage, Focal                    |                                                                          |             
      Hyperplasia, Adenomatous             |                                                                          |             
      Infiltration Cellular, Focal,        |                                                                          |             
          Histiocyte                       |                                        3                             4   |             
      Peribronchial, Inflammation, Chronic |                         1                          1  3  2               |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               | 3                    4        4           4                              |             
      Hyperkeratosis                       |                               4                                          |             
      Hyperplasia, Basal Cell              |                               3                                          |             
      Inflammation, Acute                  | 4                                                                        |             
      Inflammation, Chronic, Focal         |                         2                          2  2  2               |             
      Inflammation, Chronic                |          2        2                             3              1         |             
      Metaplasia, Squamous                 |                         2                          2  2  2               |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  59                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 4| 6| 6| 4| 7| 5| 4| 7| 2| 7| 6| 7| 5| 7| 7| 7| 4| 2| 2| 2| 3| 4| 6| 7| 7|             
                             DAY ON TEST   | 5| 3| 3| 6| 3| 2| 6| 3| 7| 3| 9| 1| 6| 1| 3| 3| 6| 7| 7| 7| 0| 6| 3| 3| 3|             
                                           | 9| 2| 2| 3| 6| 4| 2| 6| 6| 6| 5| 5| 6| 7| 6| 6| 2| 6| 6| 5| 4| 3| 9| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |             +                       +                                    |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Retina, Degeneration                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                  4                                       |             
      Mineralization                       |                                  4                                       |             
      Necrosis, Focal                      |                                                                          |             
      Nephropathy                          | 1  1  1     4  1  1  4     4  2  3  4  3  4  2  1                 1  3  2|             
      Papilla, Necrosis                    |                                  4                                       |             
      Renal Tubule, Degeneration, Granular |       3                                                                  |             
      Renal Tubule, Pigmentation, Bile     |    2                                                                    4|             
      Renal Tubule, Regeneration           |                         1                          1                     |             
                                            __________________________________________________________________________|             
   Ureter                                  |                                  +                                       |             
      Hyperplasia                          |                                  4                                       |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Calculus Micro Observation Only      |                         X                          X                     |             
      Ulcer                                |                                  4                                       |             
      Transitional Epithelium, Hyperplasia |                                  4                                       |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  60                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 2| 4| 7| 4| 7| 2| 3| 4| 7| 7| 7| 7| 5| 7| 4| 7| 7| 7| 7| 2| 6| 2| 7|             
                             DAY ON TEST   | 9| 3| 7| 6| 3| 6| 3| 7| 9| 6| 3| 3| 3| 3| 4| 3| 6| 3| 3| 3| 0| 7| 6| 7| 3|             
                                           | 8| 5| 6| 3| 5| 3| 5| 5| 1| 2| 5| 5| 5| 5| 9| 5| 3| 6| 6| 6| 1| 6| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                 2                        |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                      X   |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |                               3                                          |             
      Parasite Metazoan                    |       X                                                                  |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                                                                          |             
      Basophilic Focus                     | X  X     X  X     X        X  X  X  X  X     X  X  X  X  X              X|             
      Clear Cell Focus                     |             X     X              X                 X                     |             
      Cyst                                 |                                                       X                  |             
      Developmental Malformation           |                      X                                   X               |             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |             1                             2                              |             
      Fibrosis, Focal                      |                                                                          |             
      Hepatodiaphragmatic Nodule           |                      X  X                                                |             
      Necrosis, Focal                      |                                                                         3|             
      Proliferation                        |                                                                          |             
      Bile Duct, Hyperplasia               |          2     2                 3  3  4     4                    3      |             
      Lymphatic, Angiectasis, Focal        |                                        4                                 |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                       +                  |             
      Accessory Spleen                     |                                                       X                  |             
      Fat, Hemorrhage                      |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |    4     2  4  2                       3                 3  2     4  2   |             
      Acinus, Hyperplasia, Focal           |                                     2                                    |             
      Vein, Thrombosis                     |                                                                   X      |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Thrombosis                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
      Ulcer                                |                                                                   4      |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                           2                 1     2      |             
      Hyperplasia, Lymphoid                |    3        2                                      2  3                  |             
      Mucosa, Inflammation, Acute          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  61                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 2| 4| 7| 4| 7| 2| 3| 4| 7| 7| 7| 7| 5| 7| 4| 7| 7| 7| 7| 2| 6| 2| 7|             
                             DAY ON TEST   | 9| 3| 7| 6| 3| 6| 3| 7| 9| 6| 3| 3| 3| 3| 4| 3| 6| 3| 3| 3| 0| 7| 6| 7| 3|             
                                           | 8| 5| 6| 3| 5| 3| 5| 5| 1| 2| 5| 5| 5| 5| 9| 5| 3| 6| 6| 6| 1| 6| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 3  3  2  2  2  1  4  2  1  2        4  3     4  2  4  4  2     2     2  1|             
      Inflammation, Chronic, Focal         |                                                                          |             
      Mineralization                       | 1                                   1              1                     |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Dilatation                   |                                                                          |             
      Atrium, Thrombosis                   |                                                                   X      |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                                                          |             
      Cytoplasmic Alteration               |                                                                          |             
      Hypertrophy                          |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Focal                   |    1              1                          1                          3|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               2                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  I  +  +  +  +  +  M  +  +|             
      Ectopic Thymus                       |                                                                          |             
      Hyperplasia, Focal                   | 3                                                                       2|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                         2|             
      Pars Distalis, Cyst                  |                                                                         X|             
      Pars Distalis, Hyperplasia, Focal    |                      2        2     2           2                        |             
      Pars Intermedia, Cyst                |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |    3                                                                     |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                   3      |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              | 2     1                          2                    3                  |             
      Cyst                                 |             X                    X                                       |             
      Ectasia                              | 3                                            4                           |             
      Hyperplasia                          |                                                                          |             
      Inflammation, Chronic, Focal         |                      3                                         2     2   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  62                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 2| 4| 7| 4| 7| 2| 3| 4| 7| 7| 7| 7| 5| 7| 4| 7| 7| 7| 7| 2| 6| 2| 7|             
                             DAY ON TEST   | 9| 3| 7| 6| 3| 6| 3| 7| 9| 6| 3| 3| 3| 3| 4| 3| 6| 3| 3| 3| 0| 7| 6| 7| 3|             
                                           | 8| 5| 6| 3| 5| 3| 5| 5| 1| 2| 5| 5| 5| 5| 9| 5| 3| 6| 6| 6| 1| 6| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic                |          2     2        2  2                    2                        |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    3              3           2  3        3  3              2     3      |             
      Dilatation                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic                |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2  4        3     4           3  4  3     4  4     4     3  4     4      |             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |                                        3        3                        |             
      Interstitial Cell, Hyperplasia       |                                                                          |             
      Seminiferous Tubule, Atrophy         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    2                             2     2     2           2  4     3     4|             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                     +  +  +                 +     +      |             
      Mediastinal, Congestion              |                                                                          |             
      Mediastinal, Lymphatic, Angiectasis  |                                     3  3                    3            |             
      Pancreatic, Lymphatic, Angiectasis   |                                                             3            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                     4  4                    3            |             
      Congestion                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |    4                                                                     |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                        4     3              4            |             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |       2              2                                         1     1   |             
      Lymphatic, Angiectasis               |    3                                                                     |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Fibrosis                             |    2                          4  2     2                    2            |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Hypertrophy                          |                                                                          |             
      Infarct                              |                                                                   2      |             
      Necrosis, Focal                      |                                           3                              |             
      Thrombosis                           |                                                                          |             
      Capsule, Congestion, Focal           |                                        3                                 |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  63                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 2| 4| 7| 4| 7| 2| 3| 4| 7| 7| 7| 7| 5| 7| 4| 7| 7| 7| 7| 2| 6| 2| 7|             
                             DAY ON TEST   | 9| 3| 7| 6| 3| 6| 3| 7| 9| 6| 3| 3| 3| 3| 4| 3| 6| 3| 3| 3| 0| 7| 6| 7| 3|             
                                           | 8| 5| 6| 3| 5| 3| 5| 5| 1| 2| 5| 5| 5| 5| 9| 5| 3| 6| 6| 6| 1| 6| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Capsule, Fibrosis                    |                                           3                       3      |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
      Depletion Lymphoid                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  M  +  +  +  +  +  +  +  +  M  M  +  M  +  +  +  M  +  +  +  +  +  +|             
      Lactation                            | 3                                      4                 2        2     2|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst Epithelial Inclusion            |                                                                          |             
      Fibrosis, Focal                      |                                                                          |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Callus                               |             4                                                            |             
      Hyperostosis                         |                                                             3            |             
      Proliferation                        |                                                                          |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          | 4                                                                        |             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
      Hemorrhage, Focal                    |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Hemorrhage, Focal                    |                                                                          |             
      Hyperplasia, Adenomatous             |       2                                                                  |             
      Infiltration Cellular, Focal,        |                                                                          |             
          Histiocyte                       |                                        3                                3|             
      Peribronchial, Inflammation, Chronic |       2              2                                         2     2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |    4        4  3  4              4  4     2     4     4  4  4            |             
      Hyperkeratosis                       |                                                                          |             
      Hyperplasia, Basal Cell              |    4                                                                     |             
      Inflammation, Acute                  |                2              2                 3                        |             
      Inflammation, Chronic, Focal         |       2              2                                         2     2   |             
      Inflammation, Chronic                |          2              2  2  4                                          |             
      Metaplasia, Squamous                 |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  64                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 2| 4| 7| 4| 7| 2| 3| 4| 7| 7| 7| 7| 5| 7| 4| 7| 7| 7| 7| 2| 6| 2| 7|             
                             DAY ON TEST   | 9| 3| 7| 6| 3| 6| 3| 7| 9| 6| 3| 3| 3| 3| 4| 3| 6| 3| 3| 3| 0| 7| 6| 7| 3|             
                                           | 8| 5| 6| 3| 5| 3| 5| 5| 1| 2| 5| 5| 5| 5| 9| 5| 3| 6| 6| 6| 1| 6| 5| 5| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                  +                                       |             
      Retina, Degeneration                 |                                  4                                       |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Abscess                              |                                                                          |             
      Mineralization                       |                                                                          |             
      Necrosis, Focal                      |                                           3                              |             
      Nephropathy                          | 3  4     1  4  1  4        1  4  2  2  3  1  3     3  1  1     1        1|             
      Papilla, Necrosis                    |                                                                          |             
      Renal Tubule, Degeneration, Granular |                                                                         2|             
      Renal Tubule, Pigmentation, Bile     |                                                                          |             
      Renal Tubule, Regeneration           |       2              1                                               1   |             
                                            __________________________________________________________________________|             
   Ureter                                  |                                                                          |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  A  +  +|             
      Calculus Micro Observation Only      |       X                                                              X   |             
      Ulcer                                |                                                                          |             
      Transitional Epithelium, Hyperplasia |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  65                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 2| 7| 5| 5| 7| 6| 4| 7| 7| 7| 7| 2| 6| 6| 7| 7| 6| 6| 7|              |            |
                             DAY ON TEST   | 6| 7| 3| 9| 5| 3| 7| 6| 3| 3| 3| 3| 7| 7| 1| 3| 3| 3| 7| 3|              |            |
                                           | 2| 5| 5| 4| 0| 5| 2| 2| 5| 5| 6| 6| 5| 7| 2| 6| 6| 5| 7| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      A     |
    0 PPM                                  | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
      Parasite Metazoan                    |                            4                                             |      8  3.2|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  68        |
      Parasite Metazoan                    |                4                 2  X                                    |     10  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
      Edema                                |                                                                          |      2  3.5|
      Parasite Metazoan                    |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +               |  65        |
      Hyperplasia, Lymphoid                |                               4                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis, Focal                   |                                                                          |      2  3.5|
      Basophilic Focus                     |       X        X        X  X  X  X           X  X        X               |     39     |
      Clear Cell Focus                     |                         X     X                 X        X               |     10     |
      Cyst                                 |                X                                                         |      2     |
      Developmental Malformation           |                                                                          |      3     |
      Eosinophilic Focus                   |                                  X     X                                 |      2     |
      Fatty Change                         |             2     3                                2  3                  |      9  2.3|
      Fibrosis, Focal                      |                                                                          |      1  3.0|
      Hepatodiaphragmatic Nodule           |                            X                                             |      3     |
      Necrosis, Focal                      |                                        3                                 |      3  2.7|
      Proliferation                        |                                                                          |      1  3.0|
      Bile Duct, Hyperplasia               | 2        4  4  3     1     3  3  3     3  3        3  3                  |     24  3.0|
      Lymphatic, Angiectasis, Focal        |                                                       3                  |      2  3.5|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                         +     +                                          |   6        |
      Accessory Spleen                     |                                                                          |      1     |
      Fat, Hemorrhage                      |                                                                          |      1  4.0|
      Fat, Necrosis                        |                         4     4                                          |      3  3.7|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Acinus, Atrophy                      |       2                                3        2  4     2               |     21  2.7|
      Acinus, Hyperplasia, Focal           |                                                       2                  |      2  2.0|
      Vein, Thrombosis                     |                                                                          |      1     |
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Atrophy                              |                                                                          |      1  2.0|
      Thrombosis                           |             X                                                            |      1     |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  69        |
      Hyperkeratosis                       |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  66                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 2| 7| 5| 5| 7| 6| 4| 7| 7| 7| 7| 2| 6| 6| 7| 7| 6| 6| 7|              |            |
                             DAY ON TEST   | 6| 7| 3| 9| 5| 3| 7| 6| 3| 3| 3| 3| 7| 7| 1| 3| 3| 3| 7| 3|              |            |
                                           | 2| 5| 5| 4| 0| 5| 2| 2| 5| 5| 6| 6| 5| 7| 2| 6| 6| 5| 7| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      A     |
    0 PPM                                  | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Ulcer                                |                                                                          |      3  3.3|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  68        |
      Erosion                              |          4        3                                   1                  |      8  2.3|
      Hyperplasia, Lymphoid                |                                                                          |      4  2.5|
      Mucosa, Inflammation, Acute          |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       | 1  2  4  4     1  4  1  1  2  3  2     2  4  3     2  1  2               |     56  2.4|
      Inflammation, Chronic, Focal         |                                                                          |      2  1.5|
      Mineralization                       |                                                                          |      4  1.3|
      Artery, Inflammation, Chronic        |                                                 2                        |      1  2.0|
      Atrium, Dilatation                   |                                                                          |      1  4.0|
      Atrium, Thrombosis                   |                   X                    X  X                              |      6     |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cytoplasmic Alteration, Focal        |                2                                         2               |      2  2.0|
      Cytoplasmic Alteration               |                                                                          |      1  2.0|
      Hypertrophy                          |                                                                          |      1  3.0|
      Vacuolization Cytoplasmic            |          4        3                                                      |      3  3.3|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hemorrhage                           |                                                                          |      1  4.0|
      Hyperplasia, Focal                   |       2                 3  3  2        2  3  1     1  1  3               |     16  1.9|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hyperplasia                          |                                                                          |      4  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Ectopic Thymus                       |                                              X                           |      1     |
      Hyperplasia, Focal                   |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Pars Distalis, Angiectasis           |                                                                          |      1  2.0|
      Pars Distalis, Cyst                  |                                                                          |      1     |
      Pars Distalis, Hyperplasia, Focal    | 3           2        2                                                   |     10  2.3|
      Pars Intermedia, Cyst                |                                                                          |      1     |
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      C-Cell, Hyperplasia                  |       3                                                                  |      5  3.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  67                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 2| 7| 5| 5| 7| 6| 4| 7| 7| 7| 7| 2| 6| 6| 7| 7| 6| 6| 7|              |            |
                             DAY ON TEST   | 6| 7| 3| 9| 5| 3| 7| 6| 3| 3| 3| 3| 7| 7| 1| 3| 3| 3| 7| 3|              |            |
                                           | 2| 5| 5| 4| 0| 5| 2| 2| 5| 5| 6| 6| 5| 7| 2| 6| 6| 5| 7| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      A     |
    0 PPM                                  | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Cellular                   |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Abscess                              |          3                    3                 3                        |      7  2.4|
      Cyst                                 |             X                                                            |      4     |
      Ectasia                              |                               4           3  4                           |      5  3.6|
      Hyperplasia                          |                4                                                         |      1  4.0|
      Inflammation, Chronic, Focal         |    2                                2                                    |      8  2.1|
      Inflammation, Chronic                | 2     4           2  2  2                                                |     17  2.1|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +               |  69        |
      Atrophy                              |          4                                      3        2               |     18  2.7|
      Dilatation                           |                4  2                                                      |      2  3.0|
      Inflammation, Acute                  |                                                                          |      1  3.0|
      Inflammation, Chronic                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  M  +  +               |  68        |
      Atrophy                              |       4  4              3  3  2  3     3     4  4     2  4               |     36  3.5|
      Dilatation                           |                4                                                         |      1  4.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Bilateral, Interstitial Cell,        |                                                                          |            |
          Hyperplasia                      |                                                                          |      4  3.0|
      Interstitial Cell, Hyperplasia       |                                                                          |      1  3.0|
      Seminiferous Tubule, Atrophy         | 2                                                  4                     |      3  3.3|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hyperplasia                          |          3  4                    4        4  2     4                     |     22  3.2|
      Myelofibrosis                        |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |          +                             +                                 |  12        |
      Mediastinal, Congestion              |                                                                          |      1  3.0|
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |      4  3.0|
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Angiectasis                          |                                                                          |      4  3.5|
      Congestion                           |                      3                                                   |      1  3.0|
      Infiltration Cellular, Plasma Cell   |                                                                          |      2  4.0|
      Lymphatic, Angiectasis               |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Angiectasis                          |                                                    4                     |      5  3.8|
      Congestion                           |    3                                                                     |      1  3.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  68                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 2| 7| 5| 5| 7| 6| 4| 7| 7| 7| 7| 2| 6| 6| 7| 7| 6| 6| 7|              |            |
                             DAY ON TEST   | 6| 7| 3| 9| 5| 3| 7| 6| 3| 3| 3| 3| 7| 7| 1| 3| 3| 3| 7| 3|              |            |
                                           | 2| 5| 5| 4| 0| 5| 2| 2| 5| 5| 6| 6| 5| 7| 2| 6| 6| 5| 7| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      A     |
    0 PPM                                  | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Depletion Lymphoid                   |                                                                          |      1  3.0|
      Giant Cell                           |    1                                2                                    |      8  1.6|
      Lymphatic, Angiectasis               |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  4.0|
      Depletion Lymphoid                   |                                                                          |      3  2.7|
      Fibrosis                             |                2           3     3        4        3                     |     14  2.9|
      Hematopoietic Cell Proliferation     |                                                                          |      3  3.7|
      Hypertrophy                          |                                                                          |      1  3.0|
      Infarct                              |                                        4                                 |      2  3.0|
      Necrosis, Focal                      |                                                                          |      1  3.0|
      Thrombosis                           |                                                                          |      1     |
      Capsule, Congestion, Focal           |                                                                          |      1  3.0|
      Capsule, Fibrosis                    |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  +               |  59        |
      Depletion Lymphoid                   |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  M  M  +  +  +  M  +  +  M  +  +  +  +  +  M  +  +               |  57        |
      Lactation                            |       2           1                    3     2                           |     14  2.4|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cyst Epithelial Inclusion            |                                                                          |      1     |
      Fibrosis, Focal                      |                4        4                                                |      2  4.0|
      Ulcer                                |                         3                                                |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Callus                               |                                                                          |      1  4.0|
      Hyperostosis                         |          2  2                                                            |      5  2.2|
      Proliferation                        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Compression                          |                                                                          |      2  4.0|
      Hemorrhage                           |          3                                                               |      1  3.0|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |          +                                                               |   1        |
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |          +                                                               |   1        |
      Hemorrhage, Focal                    |          2                                                               |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  69                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 4| 2| 7| 5| 5| 7| 6| 4| 7| 7| 7| 7| 2| 6| 6| 7| 7| 6| 6| 7|              |            |
                             DAY ON TEST   | 6| 7| 3| 9| 5| 3| 7| 6| 3| 3| 3| 3| 7| 7| 1| 3| 3| 3| 7| 3|              |            |
                                           | 2| 5| 5| 4| 0| 5| 2| 2| 5| 5| 6| 6| 5| 7| 2| 6| 6| 5| 7| 6|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      A     |
    0 PPM                                  | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 NERVOUS SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                              2                           |      3  2.7|
      Hemorrhage, Focal                    |                   2                                                      |      1  2.0|
      Hyperplasia, Adenomatous             |                                                                          |      1  2.0|
      Infiltration Cellular, Focal,        |                                                                          |            |
          Histiocyte                       |                                        4                                 |      5  3.4|
      Peribronchial, Inflammation, Chronic |    2                          3     2                                    |     11  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Fungus                               |                   4     3                 4                              |     18  3.7|
      Hyperkeratosis                       |                                                                          |      1  4.0|
      Hyperplasia, Basal Cell              |                                                                          |      2  3.5|
      Inflammation, Acute                  |                                                                          |      4  2.8|
      Inflammation, Chronic, Focal         |    2                                2                                    |     10  2.0|
      Inflammation, Chronic                | 3                    3                                                   |     10  2.4|
      Metaplasia, Squamous                 |                                                                          |      4  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |          +                                                               |   3        |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Retina, Degeneration                 |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Abscess                              |                                                                          |      1  4.0|
      Mineralization                       |                                                                          |      1  4.0|
      Necrosis, Focal                      |                                                                          |      1  3.0|
      Nephropathy                          | 1  1  4  2  2  2  2  2  3  2  2  2  1  1  2  4  2  1  2  4               |     56  2.2|
      Papilla, Necrosis                    |                                                                          |      1  4.0|
      Renal Tubule, Degeneration, Granular |                                                                          |      2  2.5|
      Renal Tubule, Pigmentation, Bile     |             3                                                            |      3  3.0|
      Renal Tubule, Regeneration           |                                                                          |      5  1.2|
                                            __________________________________________________________________________|____________|
   Ureter                                  |                                                                          |   1        |
      Hyperplasia                          |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  M  +  +               |  63        |
      Calculus Micro Observation Only      |                X                                                         |      5     |
      Ulcer                                |                                                                          |      1  4.0|
      Transitional Epithelium, Hyperplasia |                                                                          |      1  4.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  70                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 3| 4| 4| 7| 7| 7| 7| 4| 2| 7| 7| 4| 7| 7| 7| 7| 2| 7| 6| 4| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 1| 6| 6| 3| 1| 3| 3| 6| 7| 3| 3| 6| 3| 3| 3| 3| 7| 3| 3| 2| 3| 7|             
                                           | 5| 4| 4| 5| 3| 2| 4| 7| 5| 4| 3| 5| 4| 4| 3| 4| 5| 4| 5| 6| 4| 9| 9| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                     2  2              4        2         |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    | X        2  3                                                  4         |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                4         |             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                            4                                             |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |       2                    2        3        3     2           2         |             
      Atrophy                              |                                                                          |             
      Basophilic Focus                     |    X  X           X  X  X  X  X     X  X     X  X  X  X     X  X     X  X|             
      Clear Cell Focus                     |                            X                 X                       X   |             
      Cyst                                 |       X                                                                  |             
      Developmental Malformation           |                                                    X                     |             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |       1              1     2                                            2|             
      Granuloma                            |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                                                   X      |             
      Infarct                              |                                                                          |             
      Necrosis, Focal                      |                      2                                                   |             
      Thrombosis                           |                                                                          |             
      Bile Duct, Dilatation                |       4                                                                  |             
      Bile Duct, Hyperplasia               |    3  2        1        2           3  3  1                    4         |             
      Lymphatic, Angiectasis, Focal        |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                         +                                      +         |             
      Fat, Necrosis                        |                         2                                                |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                         4|             
      Acinus, Atrophy                      | 2     1     1     2           2     2  3  3           1           1      |             
      Acinus, Hyperplasia, Focal           |                                              3                           |             
      Artery, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                                    +                     |             
      Palate, Inflammation, Chronic        |                                                    3                     |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Hyperplasia                          |                                                    3                     |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  71                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 3| 4| 4| 7| 7| 7| 7| 4| 2| 7| 7| 4| 7| 7| 7| 7| 2| 7| 6| 4| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 1| 6| 6| 3| 1| 3| 3| 6| 7| 3| 3| 6| 3| 3| 3| 3| 7| 3| 3| 2| 3| 7|             
                                           | 5| 4| 4| 5| 3| 2| 4| 7| 5| 4| 3| 5| 4| 4| 3| 4| 5| 4| 5| 6| 4| 9| 9| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                                                         4|             
      Hyperplasia, Lymphoid                |                   2        3                                             |             
      Submucosa, Fibrosis                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  2  3     1  1  4  2  2  2  1     3  2     3  3  2  1     4  3  2  1  1|             
      Inflammation, Chronic, Focal         |                                  1                                       |             
      Artery, Inflammation, Chronic        |                                                                      2   |             
      Atrium, Dilatation                   |                                        4                                 |             
      Ventricle, Dilatation                |                                        4                                 |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                     2                                    |             
      Hyperplasia, Focal                   |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                         4|             
      Hyperplasia, Focal                   |    3  3           2                                1  1           1  2   |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                                     X                                    |             
      Pars Distalis, Hemorrhage            |                                                                          |             
      Pars Distalis, Hyperplasia, Focal    |          2  1                             2     2     2           4  3   |             
      Pars Distalis, Inflammation, Chronic,|                                                                          |             
           Focal                           |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Ultimobranchial Cyst                 |                      X                                                   |             
      C-Cell, Hyperplasia                  |                         3              1                             2   |             
      Follicle, Cyst                       |    X                                            X                        |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |    3                                                                     |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                2              2                 3                        |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  72                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 3| 4| 4| 7| 7| 7| 7| 4| 2| 7| 7| 4| 7| 7| 7| 7| 2| 7| 6| 4| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 1| 6| 6| 3| 1| 3| 3| 6| 7| 3| 3| 6| 3| 3| 3| 3| 7| 3| 3| 2| 3| 7|             
                                           | 5| 4| 4| 5| 3| 2| 4| 7| 5| 4| 3| 5| 4| 4| 3| 4| 5| 4| 5| 6| 4| 9| 9| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Cyst                                 |                X                                                         |             
      Ectasia                              |                                                                          |             
      Inflammation, Acute                  |                         2              3                                 |             
      Inflammation, Chronic, Focal         | 2                                1                       2               |             
      Inflammation, Chronic                |          2  2  2              3           3                       2      |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                   3  2              2                          2     2   |             
      Dilatation                           |                                        2                                 |             
      Inflammation, Focal                  |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    4              3  4  4  4        4  3     3  3  4  4     4  4     4  2|             
      Dilatation                           |       3                                                                  |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                                                          |             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      | 2                                                                        |             
      Interstitial Cell, Hyperplasia       |                                  2                                       |             
      Seminiferous Tubule, Atrophy         |                      4                                                   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    4                 4     2  1        1                       4        4|             
                                            __________________________________________________________________________|             
   Lymph Node                              |                         +  +                 +     +           +        +|             
      Inguinal, Lymphatic, Angiectasis     |                                                                          |             
      Mediastinal, Congestion              |                                                                          |             
      Mediastinal, Granuloma               |                                                    4                     |             
      Mediastinal, Pigmentation            |                                                                          |             
      Mediastinal, Lymphatic, Angiectasis  |                         3                                                |             
      Pancreatic, Hyperplasia, Lymphoid    |                                              3                           |             
      Pancreatic, Lymphatic, Angiectasis   |                            4                                             |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                            3                    3                        |             
      Congestion                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                                    4                     |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           | 2                                2                       1               |             
      Lymphatic, Angiectasis               |                                     4        4                           |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Fibrosis                             |                            3        3  4        2     3     3     1     3|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  73                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 3| 4| 4| 7| 7| 7| 7| 4| 2| 7| 7| 4| 7| 7| 7| 7| 2| 7| 6| 4| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 1| 6| 6| 3| 1| 3| 3| 6| 7| 3| 3| 6| 3| 3| 3| 3| 7| 3| 3| 2| 3| 7|             
                                           | 5| 4| 4| 5| 3| 2| 4| 7| 5| 4| 3| 5| 4| 4| 3| 4| 5| 4| 5| 6| 4| 9| 9| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hematopoietic Cell Proliferation     |                      3                                                   |             
      Infarct                              |    3                 2                                                  3|             
      Thrombosis                           |                                                                          |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                                                          |             
      Hyperplasia, Lymphoid                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  M|             
      Lactation                            |                   1  1  2                       1                        |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                                                                          |             
      Inflammation, Focal, Granulomatous   |                                                                          |             
      Hair Follicle, Cyst                  |                   X                                                      |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                   2                                                      |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |          3                                                               |             
      Hemorrhage, Focal                    |                                                                          |             
      Peribronchial, Inflammation, Chronic | 2                                2                       2               |             
      Pleura, Inflammation, Chronic, Focal |                                                    2                     |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Fungus                               |       3  4  3                 4           3     4                 4     4|             
      Hyperkeratosis                       |       4                                                                  |             
      Inflammation, Acute                  |          4  2                 4           2  2                    4      |             
      Inflammation, Chronic, Focal         | 2                                2                       2               |             
      Inflammation, Chronic                |                2                                                         |             
      Metaplasia, Squamous                 | 2                                                                        |             
      Respiratory Epithelium, Necrosis     |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                        M                                 |             
      Cataract                             |                                                                          |             
      Retina, Degeneration                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  74                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 3| 4| 4| 7| 7| 7| 7| 4| 2| 7| 7| 4| 7| 7| 7| 7| 2| 7| 6| 4| 7| 6|             
                             DAY ON TEST   | 7| 3| 3| 1| 6| 6| 3| 1| 3| 3| 6| 7| 3| 3| 6| 3| 3| 3| 3| 7| 3| 3| 2| 3| 7|             
                                           | 5| 4| 4| 5| 3| 2| 4| 7| 5| 4| 3| 5| 4| 4| 3| 4| 5| 4| 5| 6| 4| 9| 9| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                X         |             
      Glomerulosclerosis                   |                                                                          |             
      Nephropathy                          | 1  3  2     2  2  2  1  2  3  2     4  3  2  2  2  1  3     3     3  3  2|             
      Medulla, Casts                       |                      X                                                   |             
      Renal Tubule, Degeneration, Granular |                                                                2         |             
      Renal Tubule, Pigmentation, Bile     |                                                                         3|             
      Renal Tubule, Regeneration           |                                  1                                       |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calculus Micro Observation Only      |                                                          X               |             
      Hemorrhage                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  75                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 2| 6| 6| 2| 7| 4| 2| 7| 7| 7| 4| 2| 7| 7| 4| 7| 4| 7| 4| 0| 7| 2| 7| 2|             
                             DAY ON TEST   | 5| 7| 7| 8| 7| 3| 6| 7| 3| 3| 3| 6| 7| 2| 3| 6| 3| 6| 3| 6| 4| 3| 7| 3| 7|             
                                           | 0| 6| 5| 7| 6| 4| 3| 6| 4| 4| 4| 3| 5| 4| 4| 3| 4| 3| 4| 2| 3| 4| 5| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    100 PPM                                | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |          4     4                                                         |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |             X  2           4              4        4                    X|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Parasite Metazoan                    |             X                 2                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |          2                                                               |             
      Atrophy                              |                                                                          |             
      Basophilic Focus                     |          X     X        X  X  X        X  X  X  X  X  X        X     X   |             
      Clear Cell Focus                     |                            X  X                                          |             
      Cyst                                 |                                                                          |             
      Developmental Malformation           |                                                                          |             
      Eosinophilic Focus                   |                                                                          |             
      Fatty Change                         |                                                                          |             
      Granuloma                            |                                                    3                     |             
      Hepatodiaphragmatic Nodule           |                                                          X               |             
      Infarct                              | 4                                                                        |             
      Necrosis, Focal                      |                                                                          |             
      Thrombosis                           | X                                                                        |             
      Bile Duct, Dilatation                |                                                                          |             
      Bile Duct, Hyperplasia               |       3        3  1     3  3     1        3     4  1  2  2     3  2  2   |             
      Lymphatic, Angiectasis, Focal        |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |          +        +                       +                              |             
      Fat, Necrosis                        |                   3                       4                              |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Acinus, Atrophy                      |       4                 1     2        2  2  2  4     3  1               |             
      Acinus, Hyperplasia, Focal           |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Pharynx                                 |                                                                          |             
      Palate, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic, Focal         |                                                                          |             
      Ulcer                                |          4                                                               |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  76                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 2| 6| 6| 2| 7| 4| 2| 7| 7| 7| 4| 2| 7| 7| 4| 7| 4| 7| 4| 0| 7| 2| 7| 2|             
                             DAY ON TEST   | 5| 7| 7| 8| 7| 3| 6| 7| 3| 3| 3| 6| 7| 2| 3| 6| 3| 6| 3| 6| 4| 3| 7| 3| 7|             
                                           | 0| 6| 5| 7| 6| 4| 3| 6| 4| 4| 4| 3| 5| 4| 4| 3| 4| 3| 4| 2| 3| 4| 5| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    100 PPM                                | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              | 3     3  1                                                               |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Submucosa, Fibrosis                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 1  1           3  2     4  2  3  2        2  2  3  1  1  2     2     3   |             
      Inflammation, Chronic, Focal         |                      1              1                             1     1|             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Dilatation                   |                                                                          |             
      Ventricle, Dilatation                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                               3                                          |             
      Hyperplasia, Focal                   |                                                                          |             
      Vacuolization Cytoplasmic            |          3                                                               |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Focal                   |                1        2  1                                             |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                X                                      X                  |             
      Pars Distalis, Hemorrhage            |                                                       4                  |             
      Pars Distalis, Hyperplasia, Focal    |    1              1        2                             2               |             
      Pars Distalis, Inflammation, Chronic,|                                                                          |             
           Focal                           |                                                    2                     |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ultimobranchial Cyst                 |                                                                          |             
      C-Cell, Hyperplasia                  |                1                                                         |             
      Follicle, Cyst                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                   2      |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  77                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 2| 6| 6| 2| 7| 4| 2| 7| 7| 7| 4| 2| 7| 7| 4| 7| 4| 7| 4| 0| 7| 2| 7| 2|             
                             DAY ON TEST   | 5| 7| 7| 8| 7| 3| 6| 7| 3| 3| 3| 6| 7| 2| 3| 6| 3| 6| 3| 6| 4| 3| 7| 3| 7|             
                                           | 0| 6| 5| 7| 6| 4| 3| 6| 4| 4| 4| 3| 5| 4| 4| 3| 4| 3| 4| 2| 3| 4| 5| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    100 PPM                                | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Cyst                                 |                            X  X                                X     X   |             
      Ectasia                              |                                        3                                 |             
      Inflammation, Acute                  |                                        2  2                              |             
      Inflammation, Chronic, Focal         |    2                 3              3                                   3|             
      Inflammation, Chronic                |                   2              2                 1                     |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       3        2        2              2                       3     2   |             
      Dilatation                           |                                                                          |             
      Inflammation, Focal                  |                   3                                                      |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       4  2     3        3  4  4        3  3           3        4     4   |             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                                                          |             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |                                                                          |             
      Interstitial Cell, Hyperplasia       |          3                                                               |             
      Seminiferous Tubule, Atrophy         |       4  4  1                                                            |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood                                   |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 4                       4              4        3              4     3   |             
                                            __________________________________________________________________________|             
   Lymph Node                              | +     +  +     +  +        +           +        +              +         |             
      Inguinal, Lymphatic, Angiectasis     |                                                                          |             
      Mediastinal, Congestion              |                   3                                                      |             
      Mediastinal, Granuloma               |                                                                          |             
      Mediastinal, Pigmentation            |                                                                3         |             
      Mediastinal, Lymphatic, Angiectasis  |                                                                2         |             
      Pancreatic, Hyperplasia, Lymphoid    |                                                                          |             
      Pancreatic, Lymphatic, Angiectasis   | 3              3                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |                                                                          |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                         3              4                                 |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |    2        2        2              1                             2     1|             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                             3            |             
      Depletion Lymphoid                   |                                                                          |             
      Fibrosis                             | 3                                      4        3                    4   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  78                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 2| 6| 6| 2| 7| 4| 2| 7| 7| 7| 4| 2| 7| 7| 4| 7| 4| 7| 4| 0| 7| 2| 7| 2|             
                             DAY ON TEST   | 5| 7| 7| 8| 7| 3| 6| 7| 3| 3| 3| 6| 7| 2| 3| 6| 3| 6| 3| 6| 4| 3| 7| 3| 7|             
                                           | 0| 6| 5| 7| 6| 4| 3| 6| 4| 4| 4| 3| 5| 4| 4| 3| 4| 3| 4| 2| 3| 4| 5| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    100 PPM                                | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Infarct                              | 4        4                                                               |             
      Thrombosis                           | X                                                                        |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                                             2            |             
      Hyperplasia, Lymphoid                |                   2                                                      |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  M  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Lactation                            |          2              1  1              1     1     1                  |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acanthosis                           |                                                                      3   |             
      Inflammation, Focal, Granulomatous   |                                                                          |             
      Hair Follicle, Cyst                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |       4                                4                                 |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage, Focal                    |                                                             4            |             
      Peribronchial, Inflammation, Chronic |    2        2        2              1                             2     2|             
      Pleura, Inflammation, Chronic, Focal |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               | 4        4                       3                    4              4   |             
      Hyperkeratosis                       |                                                                          |             
      Inflammation, Acute                  |                                  3                                       |             
      Inflammation, Chronic, Focal         |    2        2        2              1                             2     2|             
      Inflammation, Chronic                |                   2                          1     2     2               |             
      Metaplasia, Squamous                 |                                                                          |             
      Respiratory Epithelium, Necrosis     |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                +           +                                             |             
      Cataract                             |                2                                                         |             
      Retina, Degeneration                 |                            3                                             |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  79                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 2| 6| 6| 2| 7| 4| 2| 7| 7| 7| 4| 2| 7| 7| 4| 7| 4| 7| 4| 0| 7| 2| 7| 2|             
                             DAY ON TEST   | 5| 7| 7| 8| 7| 3| 6| 7| 3| 3| 3| 6| 7| 2| 3| 6| 3| 6| 3| 6| 4| 3| 7| 3| 7|             
                                           | 0| 6| 5| 7| 6| 4| 3| 6| 4| 4| 4| 3| 5| 4| 4| 3| 4| 3| 4| 2| 3| 4| 5| 4| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    100 PPM                                | 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Glomerulosclerosis                   | 3                                                                        |             
      Nephropathy                          |       1  2     2  2  1  2  2  3  2     2  1  1  1  1  3        2     2  1|             
      Medulla, Casts                       |                                                                          |             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |       1                                                                  |             
      Renal Tubule, Regeneration           |    1        1                                                     1      |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Calculus Micro Observation Only      |                                                                          |             
      Hemorrhage                           |       2                                                                  |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  80                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 5| 6| 7| 7| 5| 6| 7| 4| 7| 6| 5| 7| 7| 4| 7| 7| 7| 7| 7|              |            |
                             DAY ON TEST   | 7| 3| 5| 3| 3| 4| 2| 3| 6| 3| 0| 9| 3| 3| 0| 3| 3| 3| 3| 3|              |            |
                                           | 6| 3| 0| 5| 5| 7| 3| 5| 2| 5| 0| 6| 5| 5| 9| 5| 5| 5| 5| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|              |      A     |
    100 PPM                                | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
      Parasite Metazoan                    |       3     2                                                            |      8  2.9|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  67        |
      Parasite Metazoan                    |          4  4        2  2              3                                 |     15  3.2|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  A  +  +  +  +  +  A  +  +  A  +  +  +  +  +               |  64        |
      Hyperplasia, Lymphoid                |                                                                          |      1  4.0|
      Parasite Metazoan                    | X           4                                                            |      4  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  69        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +               |  66        |
      Hyperplasia, Lymphoid                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  A  +  +  A  +  +  +  +  +  A  +  +  A  +  +  +  +  +               |  63        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis, Focal                   |                                                                          |      7  2.3|
      Atrophy                              |                2                                                         |      1  2.0|
      Basophilic Focus                     |       X  X  X  X  X  X  X  X     X  X  X     X  X  X  X  X               |     46     |
      Clear Cell Focus                     |          X  X                       X                                    |      8     |
      Cyst                                 |                                                                          |      1     |
      Developmental Malformation           |                                                                          |      1     |
      Eosinophilic Focus                   |                                                          X               |      1     |
      Fatty Change                         |                                           3                              |      5  1.8|
      Granuloma                            |                                                                          |      1  3.0|
      Hepatodiaphragmatic Nodule           |                                                 X                        |      3     |
      Infarct                              |                                                                          |      1  4.0|
      Necrosis, Focal                      |                                                                          |      1  2.0|
      Thrombosis                           |                                                                          |      1     |
      Bile Duct, Dilatation                |                                                                          |      1  4.0|
      Bile Duct, Hyperplasia               |       2  2              1     4     2        3     4  4  4               |     31  2.5|
      Lymphatic, Angiectasis, Focal        |                      3                                                   |      1  3.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                               +                    +                     |   7        |
      Fat, Necrosis                        |                               3                    4                     |      5  3.2|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                                                          |      1  4.0|
      Acinus, Atrophy                      |    4     2  4           1                    2  4  4  4  3               |     28  2.4|
      Acinus, Hyperplasia, Focal           |                3                                                         |      2  3.0|
      Artery, Inflammation, Chronic        |                                        3                                 |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pharynx                                 |                                                                          |   1        |
      Palate, Inflammation, Chronic        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  81                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 5| 6| 7| 7| 5| 6| 7| 4| 7| 6| 5| 7| 7| 4| 7| 7| 7| 7| 7|              |            |
                             DAY ON TEST   | 7| 3| 5| 3| 3| 4| 2| 3| 6| 3| 0| 9| 3| 3| 0| 3| 3| 3| 3| 3|              |            |
                                           | 6| 3| 0| 5| 5| 7| 3| 5| 2| 5| 0| 6| 5| 5| 9| 5| 5| 5| 5| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|              |      A     |
    100 PPM                                | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Atrophy                              |                   2                                                      |      1  2.0|
      Hyperplasia                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Inflammation, Chronic, Focal         |                               1                                          |      1  1.0|
      Ulcer                                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Erosion                              |       2                                                                  |      5  2.6|
      Hyperplasia, Lymphoid                |                                                                          |      2  2.5|
      Submucosa, Fibrosis                  |                   3                                                      |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       |       1  2  1        3  2  3  2        3  2  2  1     2  1               |     50  2.1|
      Inflammation, Chronic, Focal         | 1                                                                        |      6  1.0|
      Artery, Inflammation, Chronic        |                                                                          |      1  2.0|
      Atrium, Dilatation                   |                                                                          |      1  4.0|
      Ventricle, Dilatation                |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cytoplasmic Alteration, Focal        |          2                                               2               |      4  2.3|
      Hyperplasia, Focal                   |                                                    4                     |      1  4.0|
      Vacuolization Cytoplasmic            |    3                                                                     |      2  3.0|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Hemorrhage                           |                                                                          |      1  4.0|
      Hyperplasia, Focal                   |          3                                         2                     |     12  1.8|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +               |  66        |
      Hyperplasia, Focal                   |                                                          2               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Pars Distalis, Angiectasis           |       2        2                                                         |      2  2.0|
      Pars Distalis, Cyst                  |                                                                          |      3     |
      Pars Distalis, Hemorrhage            |                                                                          |      1  4.0|
      Pars Distalis, Hyperplasia, Focal    |    2                             4           2                           |     14  2.1|
      Pars Distalis, Inflammation, Chronic,|                                                                          |            |
           Focal                           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Ultimobranchial Cyst                 |                                                                          |      1     |
      C-Cell, Hyperplasia                  |                                              3        1                  |      6  1.8|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  82                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 5| 6| 7| 7| 5| 6| 7| 4| 7| 6| 5| 7| 7| 4| 7| 7| 7| 7| 7|              |            |
                             DAY ON TEST   | 7| 3| 5| 3| 3| 4| 2| 3| 6| 3| 0| 9| 3| 3| 0| 3| 3| 3| 3| 3|              |            |
                                           | 6| 3| 0| 5| 5| 7| 3| 5| 2| 5| 0| 6| 5| 5| 9| 5| 5| 5| 5| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|              |      A     |
    100 PPM                                | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Follicle, Cyst                       |                                                                          |      2     |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Depletion Cellular                   |                                                       2                  |      2  2.5|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
      Abscess                              |                                                                          |      4  2.3|
      Cyst                                 |                                                                          |      5     |
      Ectasia                              |                                  2                                       |      2  2.5|
      Inflammation, Acute                  |                            3                                             |      5  2.4|
      Inflammation, Chronic, Focal         | 2                                                                        |      8  2.3|
      Inflammation, Chronic                |                         3                 3                              |     11  2.3|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Atrophy                              |                                                                          |     11  2.3|
      Dilatation                           |                                                                          |      1  2.0|
      Inflammation, Focal                  |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Atrophy                              |       3  3        3                 4  4     3  3  3  3  3               |     36  3.4|
      Dilatation                           |                3                          2                              |      3  2.7|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hemorrhage, Focal                    |    4                                                                     |      1  4.0|
      Bilateral, Interstitial Cell,        |                                                                          |            |
          Hyperplasia                      |                                                                          |      1  2.0|
      Interstitial Cell, Hyperplasia       |                3                                3  3                     |      5  2.8|
      Seminiferous Tubule, Atrophy         |                                                    4                     |      5  3.4|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood                                   |                               +                                          |   1        |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |       2        4                    2              2  2  4               |     19  3.1|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |    +                          +                    +     +               |  19        |
      Inguinal, Lymphatic, Angiectasis     |                                                          3               |      1  3.0|
      Mediastinal, Congestion              |                                                                          |      1  3.0|
      Mediastinal, Granuloma               |                                                                          |      1  4.0|
      Mediastinal, Pigmentation            |                                                                          |      1  3.0|
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |      2  2.5|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  83                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 5| 6| 7| 7| 5| 6| 7| 4| 7| 6| 5| 7| 7| 4| 7| 7| 7| 7| 7|              |            |
                             DAY ON TEST   | 7| 3| 5| 3| 3| 4| 2| 3| 6| 3| 0| 9| 3| 3| 0| 3| 3| 3| 3| 3|              |            |
                                           | 6| 3| 0| 5| 5| 7| 3| 5| 2| 5| 0| 6| 5| 5| 9| 5| 5| 5| 5| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|              |      A     |
    100 PPM                                | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Pancreatic, Hyperplasia, Lymphoid    |                                                                          |      1  3.0|
      Pancreatic, Lymphatic, Angiectasis   |                                                    3                     |      4  3.3|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Angiectasis                          |                                                                          |      2  3.0|
      Congestion                           |                   4                                                      |      1  4.0|
      Infiltration Cellular, Plasma Cell   |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis                          |                                     4        3     4                     |      5  3.6|
      Depletion Lymphoid                   |                   4                                                      |      1  4.0|
      Giant Cell                           | 2                                                                        |     10  1.7|
      Lymphatic, Angiectasis               |                                                                          |      2  4.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |    2                                                                     |      2  2.5|
      Depletion Lymphoid                   |                   4              3                                       |      2  3.5|
      Fibrosis                             |          2                 3        3                 4  4               |     17  3.1|
      Hematopoietic Cell Proliferation     |                3                                                         |      2  3.0|
      Infarct                              |    4  2                                                                  |      7  3.1|
      Thrombosis                           |                                                                          |      1     |
      Capsule, Fibrosis                    |                1                                                         |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  +               |  67        |
      Hemorrhage, Focal                    |                                                                          |      1  2.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  +  M  +  +  +  M  +  +  M  +  M  M  +  +  +  +  +  M  +               |  53        |
      Lactation                            |    1        2  2              1                                          |     14  1.3|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Acanthosis                           |                                                                          |      1  3.0|
      Inflammation, Focal, Granulomatous   |                      3                                                   |      1  3.0|
      Hair Follicle, Cyst                  |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |                            2                                             |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hemorrhage                           |                                                                          |      2  4.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  84                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 5| 6| 7| 7| 5| 6| 7| 4| 7| 6| 5| 7| 7| 4| 7| 7| 7| 7| 7|              |            |
                             DAY ON TEST   | 7| 3| 5| 3| 3| 4| 2| 3| 6| 3| 0| 9| 3| 3| 0| 3| 3| 3| 3| 3|              |            |
                                           | 6| 3| 0| 5| 5| 7| 3| 5| 2| 5| 0| 6| 5| 5| 9| 5| 5| 5| 5| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|              |      A     |
    100 PPM                                | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  3.0|
      Hemorrhage, Focal                    |                                                                          |      1  4.0|
      Peribronchial, Inflammation, Chronic | 2                                                                        |     10  1.9|
      Pleura, Inflammation, Chronic, Focal |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Fungus                               |       4     4     4           4  2                                       |     18  3.7|
      Hyperkeratosis                       |                                                                          |      1  4.0|
      Inflammation, Acute                  |    2                                                     1               |      9  2.7|
      Inflammation, Chronic, Focal         | 2                                                                        |     10  1.9|
      Inflammation, Chronic                |                         2                 2                              |      7  1.9|
      Metaplasia, Squamous                 |                                                                          |      1  2.0|
      Respiratory Epithelium, Necrosis     |                   4                                                      |      1  4.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                          +               |   3        |
      Cataract                             |                                                                          |      1  2.0|
      Retina, Degeneration                 |                                                          4               |      2  3.5|
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cyst                                 |             X                                                            |      2     |
      Glomerulosclerosis                   |                                                                          |      1  3.0|
      Nephropathy                          |       2  3  4  1  2  2  1  1  1  2  4  1  1  2  1  1  2  4               |     57  2.0|
      Medulla, Casts                       |                                                                          |      1     |
      Renal Tubule, Degeneration, Granular |    3                                                                     |      2  2.5|
      Renal Tubule, Pigmentation, Bile     |                                                                          |      2  2.0|
      Renal Tubule, Regeneration           |                                                                          |      4  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  M  +  +  A  +  +  +  +  +  A  +  +  A  +  +  +  +  +               |  64        |
      Calculus Micro Observation Only      |                                                                          |      1     |
      Hemorrhage                           |                                                                          |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  85                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 7| 7| 4| 7| 7| 7| 6| 3| 4| 3| 6| 7| 7| 4| 2| 7| 7| 4| 7| 7| 2| 7|             
                             DAY ON TEST   | 7| 3| 3| 3| 3| 6| 3| 3| 3| 5| 2| 6| 8| 2| 3| 3| 6| 7| 3| 3| 6| 0| 3| 7| 2|             
                                           | 5| 1| 1| 1| 1| 2| 1| 1| 1| 3| 5| 3| 3| 4| 1| 1| 3| 5| 4| 1| 3| 0| 1| 6| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  M  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                    X     4  4            |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |       2                       4                    X  3              X   |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  A|             
      Peyer's Patch, Hyperplasia           |                                                 3                        |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                                           2                              |             
      Atrophy                              |                                                                         3|             
      Basophilic Focus                     |    X  X  X  X     X  X  X  X           X  X  X        X  X        X     X|             
      Clear Cell Focus                     |             X        X                    X  X                           |             
      Developmental Malformation           |             X                                                            |             
      Fatty Change                         |                      1                                         2         |             
      Fibrosis, Focal                      |                                                                          |             
      Granuloma                            |                                        4  2                              |             
      Hepatodiaphragmatic Nodule           |                                     X                 X                  |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Thrombosis                           |                                                                          |             
      Bile Duct, Hyperplasia               | 2  3  3  3     1        3                                3  2           2|             
      Lymphatic, Angiectasis, Focal        |       3              4                                                   |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +           +        +              +           +                  |             
      Accessory Spleen                     |                                                                          |             
      Cyst                                 |                            X                                             |             
      Fibrosis                             |                                                                          |             
      Fat, Necrosis                        |       3           3        3              3           4                  |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pigmentation, Focal                  |                                                                          |             
      Acinus, Atrophy                      |       3     2     3     2                                   2        1   |             
      Acinus, Hyperplasia, Focal           |                                                                          |             
      Artery, Inflammation, Chronic        |                                              2                           |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst Epithelial Inclusion            |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                                                         4|             
      Hyperplasia, Lymphoid                |                                                       3                  |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  86                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 7| 7| 4| 7| 7| 7| 6| 3| 4| 3| 6| 7| 7| 4| 2| 7| 7| 4| 7| 7| 2| 7|             
                             DAY ON TEST   | 7| 3| 3| 3| 3| 6| 3| 3| 3| 5| 2| 6| 8| 2| 3| 3| 6| 7| 3| 3| 6| 0| 3| 7| 2|             
                                           | 5| 1| 1| 1| 1| 2| 1| 1| 1| 3| 5| 3| 3| 4| 1| 1| 3| 5| 4| 1| 3| 0| 1| 6| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2     1  2  1  1  2  1     2     1        2  2  1  2  3           2  2  2|             
      Inflammation, Chronic, Focal         |                                                                          |             
      Mineralization                       |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Thrombosis                   |                                                       X                  |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                                                         3|             
      Hyperplasia                          |                                                                          |             
      Vacuolization Cytoplasmic            |                                                                3         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |    2  3           1  2  2                             1                  |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hyperplasia, Focal    | 1                                3  2        2  2           1  3     2   |             
      Pars Intermedia, Hyperplasia, Focal  |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                     2                          2        2|             
      Follicle, Cyst                       |                                                          X               |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |                                                                          |             
      Spermatocele                         |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |       X                                         X                        |             
      Ectasia                              |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         | 3                                                  2                 3   |             
      Inflammation, Chronic                |                2                 2  2                       3            |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    2     2        2                          3           3        3     4|             
      Congestion                           |                                                                          |             
      Dilatation                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  87                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 7| 7| 4| 7| 7| 7| 6| 3| 4| 3| 6| 7| 7| 4| 2| 7| 7| 4| 7| 7| 2| 7|             
                             DAY ON TEST   | 7| 3| 3| 3| 3| 6| 3| 3| 3| 5| 2| 6| 8| 2| 3| 3| 6| 7| 3| 3| 6| 0| 3| 7| 2|             
                                           | 5| 1| 1| 1| 1| 2| 1| 1| 1| 3| 5| 3| 3| 4| 1| 1| 3| 5| 4| 1| 3| 0| 1| 6| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    4     4  4     4     4  3              3  4           4     2  4     4|             
      Cyst                                 |                                                                          |             
      Dilatation                           |                      3                                                   |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |                                     2              2        3            |             
      Interstitial Cell, Hyperplasia       |                                                                          |             
      Seminiferous Tubule, Atrophy         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |                                           4                              |             
      Hyperplasia                          |    4  3           4     1           2                 3        4  2     2|             
      Myelofibrosis                        |                      1     1                                             |             
                                            __________________________________________________________________________|             
   Lymph Node                              |    +  +                 +  +              +        +           +        +|             
      Lumbar, Lymphatic, Angiectasis       |                                                                         3|             
      Mediastinal, Congestion              |                                                    2                     |             
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |             
      Pancreatic, Lymphatic, Angiectasis   |                         4                                      3         |             
      Renal, Pigmentation                  |    4                                                                     |             
      Renal, Lymphatic, Angiectasis        |    3                                                                     |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Depletion Lymphoid                   |                                                                         3|             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Depletion Lymphoid                   |                                                                         4|             
      Giant Cell                           | 2                                                  1                 2   |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Lymphatic, Angiectasis               |                      4                                4                  |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                        4                          2     4|             
      Fibrosis                             |    2              3     4                                                |             
      Hematopoietic Cell Proliferation     |                                     2                                    |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|             
      Cyst                                 |                                                                          |             
      Depletion Lymphoid                   |                                                                         4|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  M  M  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  88                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 7| 7| 4| 7| 7| 7| 6| 3| 4| 3| 6| 7| 7| 4| 2| 7| 7| 4| 7| 7| 2| 7|             
                             DAY ON TEST   | 7| 3| 3| 3| 3| 6| 3| 3| 3| 5| 2| 6| 8| 2| 3| 3| 6| 7| 3| 3| 6| 0| 3| 7| 2|             
                                           | 5| 1| 1| 1| 1| 2| 1| 1| 1| 3| 5| 3| 3| 4| 1| 1| 3| 5| 4| 1| 3| 0| 1| 6| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lactation                            |    2                       1              1                              |             
                                            __________________________________________________________________________|             
   Skin                                    | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                          3               |             
      Fibrosis, Focal                      |                                                                          |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                                                          |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
      Fibrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                         +|             
      Degeneration                         |                                                                         4|             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                         +|             
      Degeneration                         |                                                                         4|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |                                                                          |             
      Peribronchial, Inflammation, Chronic | 2                                                  2                 2   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |    4                       3                                            4|             
      Hyperkeratosis                       |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic, Focal         | 2                                                  2                 1   |             
      Inflammation, Chronic                |                2              2  2  2           2           2            |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                     +                                    |             
      Cataract                             |                                     2                                    |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Glomerulosclerosis                   |                                        3                                 |             
      Nephropathy                          | 1  2  2  1  1  2  2  1  2  1     2  1     3  4  1     1  1  1  1  1     1|             
      Renal Tubule, Degeneration, Granular |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |    3                       4                                   4         |             
      Renal Tubule, Regeneration           |                                                    1                 2   |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  89                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 7| 7| 7| 7| 4| 7| 7| 7| 6| 3| 4| 3| 6| 7| 7| 4| 2| 7| 7| 4| 7| 7| 2| 7|             
                             DAY ON TEST   | 7| 3| 3| 3| 3| 6| 3| 3| 3| 5| 2| 6| 8| 2| 3| 3| 6| 7| 3| 3| 6| 0| 3| 7| 2|             
                                           | 5| 1| 1| 1| 1| 2| 1| 1| 1| 3| 5| 3| 3| 4| 1| 1| 3| 5| 4| 1| 3| 0| 1| 6| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Calculus Micro Observation Only      |                                                                          |             
      Ectasia                              |                                                                         2|             
      Hemorrhage                           |                                                                         3|             
      Inflammation, Chronic, Focal         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  90                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 4| 7| 4| 7| 7| 7| 4| 5| 7| 7| 4| 6| 7| 7| 7| 2| 7| 6| 7| 4| 6| 6|             
                             DAY ON TEST   | 7| 7| 0| 0| 3| 6| 3| 3| 3| 6| 4| 3| 2| 6| 7| 3| 3| 3| 7| 3| 8| 3| 6| 3| 7|             
                                           | 5| 5| 1| 6| 1| 3| 1| 1| 1| 3| 2| 1| 2| 2| 4| 4| 4| 4| 6| 4| 1| 1| 2| 8| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                         2           2        2              4            |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    | X  X        2  4  4                                4           3  4      |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  A  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                         4                                                |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  A  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Peyer's Patch, Hyperplasia           |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                                           2                    3         |             
      Atrophy                              |          3                                                               |             
      Basophilic Focus                     |             X     X  X  X        X  X  X  X  X  X  X     X     X  X  X   |             
      Clear Cell Focus                     |                         X                    X           X              X|             
      Developmental Malformation           |                                                    X                     |             
      Fatty Change                         |       2                                                           1      |             
      Fibrosis, Focal                      |                                                                          |             
      Granuloma                            |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                                 X                        |             
      Mixed Cell Focus                     |                   X                                                      |             
      Necrosis, Focal                      |       2                                                                  |             
      Thrombosis                           |                                                                          |             
      Bile Duct, Hyperplasia               |    2  4              3                          4              3  2     3|             
      Lymphatic, Angiectasis, Focal        |       3                                                                  |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +           +  +           +  +           +                       +|             
      Accessory Spleen                     |                                                 X                        |             
      Cyst                                 |                                                                          |             
      Fibrosis                             |                                                                          |             
      Fat, Necrosis                        |                   2  3           3                                      3|             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pigmentation, Focal                  |       3                                                                  |             
      Acinus, Atrophy                      |             2              1        4  1        2     2                  |             
      Acinus, Hyperplasia, Focal           |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +     +|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst Epithelial Inclusion            |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Erosion                              |       3                       3                                          |             
      Hyperplasia, Lymphoid                |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  91                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 4| 7| 4| 7| 7| 7| 4| 5| 7| 7| 4| 6| 7| 7| 7| 2| 7| 6| 7| 4| 6| 6|             
                             DAY ON TEST   | 7| 7| 0| 0| 3| 6| 3| 3| 3| 6| 4| 3| 2| 6| 7| 3| 3| 3| 7| 3| 8| 3| 6| 3| 7|             
                                           | 5| 5| 1| 6| 1| 3| 1| 1| 1| 3| 2| 1| 2| 2| 4| 4| 4| 4| 6| 4| 1| 1| 2| 8| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |    1  2  2  2  2  3  2  2  2     2  3  3  1  1  1  3     3     3     1  2|             
      Inflammation, Chronic, Focal         | 1                                                     2                  |             
      Mineralization                       |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Thrombosis                   |                                                 X                       X|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                                                          |             
      Hyperplasia                          |       2                                                  2               |             
      Vacuolization Cytoplasmic            |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |             1     2  1                 2  2                          2  1|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                           3                              |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|             
      Hyperplasia, Focal                   |                      2                                                   |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Cyst                  |                                                          X     X         |             
      Pars Distalis, Hyperplasia, Focal    |                2                          2  2     2  2                  |             
      Pars Intermedia, Hyperplasia, Focal  |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                              4                          2|             
      Follicle, Cyst                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Depletion Cellular                   |             3                                                            |             
      Spermatocele                         |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Ectasia                              |                                              3                           |             
      Inflammation, Acute                  |                                              3                           |             
      Inflammation, Chronic, Focal         | 2  2                                                  2                  |             
      Inflammation, Chronic                |          2     2           2           2                          2      |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |             3           3        3           3                           |             
      Congestion                           |                                                                          |             
      Dilatation                           |                                                    3                     |             
      Inflammation, Acute                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  92                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 4| 7| 4| 7| 7| 7| 4| 5| 7| 7| 4| 6| 7| 7| 7| 2| 7| 6| 7| 4| 6| 6|             
                             DAY ON TEST   | 7| 7| 0| 0| 3| 6| 3| 3| 3| 6| 4| 3| 2| 6| 7| 3| 3| 3| 7| 3| 8| 3| 6| 3| 7|             
                                           | 5| 5| 1| 6| 1| 3| 1| 1| 1| 3| 2| 1| 2| 2| 4| 4| 4| 4| 6| 4| 1| 1| 2| 8| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       3     4     4  3           3     2  3  4  4        4  3  3     2  4|             
      Cyst                                 |                         X                                                |             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |    2                                                                     |             
      Interstitial Cell, Hyperplasia       |          2                                                               |             
      Seminiferous Tubule, Atrophy         |                               3                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |                                                                          |             
      Hyperplasia                          |       3  2           2        3  4  4        3  4  4           4     2  4|             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |       +     +                                +  +              +         |             
      Lumbar, Lymphatic, Angiectasis       |                                                                          |             
      Mediastinal, Congestion              |                                                                          |             
      Mediastinal, Lymphatic, Angiectasis  |       4     3                                                            |             
      Pancreatic, Lymphatic, Angiectasis   |                                              3                           |             
      Renal, Pigmentation                  |                                                                          |             
      Renal, Lymphatic, Angiectasis        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Angiectasis                          |             2        3                                                   |             
      Depletion Lymphoid                   |                                                                          |             
      Lymphatic, Angiectasis               |                                                             3            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  M  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                      4                                                   |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           | 1  2                                                  2                  |             
      Hyperplasia, Lymphoid                |                                     3                                    |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                     4                                    |             
      Depletion Lymphoid                   |          3                    4                                          |             
      Fibrosis                             |                      2                    4        2                     |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Capsule, Fibrosis                    |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Cyst                                 |                                                                      X   |             
      Depletion Lymphoid                   |          4                                                               |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  M  +  +  M  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  93                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 4| 7| 4| 7| 7| 7| 4| 5| 7| 7| 4| 6| 7| 7| 7| 2| 7| 6| 7| 4| 6| 6|             
                             DAY ON TEST   | 7| 7| 0| 0| 3| 6| 3| 3| 3| 6| 4| 3| 2| 6| 7| 3| 3| 3| 7| 3| 8| 3| 6| 3| 7|             
                                           | 5| 5| 1| 6| 1| 3| 1| 1| 1| 3| 2| 1| 2| 2| 4| 4| 4| 4| 6| 4| 1| 1| 2| 8| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lactation                            |                   1                 1           1  1     1     1        2|             
                                            __________________________________________________________________________|             
   Skin                                    | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Fibrosis, Focal                      |                                                                          |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |             2                    2                       2               |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |       +              +              +                       +            |             
      Fibrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
      Degeneration                         |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
      Degeneration                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Granuloma                            |             2           2           2                                    |             
      Peribronchial, Inflammation, Chronic | 2  2                                                  2                  |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                      3  3     4     3     4  3              4            |             
      Hyperkeratosis                       |                                                             4            |             
      Inflammation, Acute                  |                                                          1               |             
      Inflammation, Chronic, Focal         | 1  2                                                  2                  |             
      Inflammation, Chronic                |                2           2           2                          2      |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |             +                                            +               |             
      Cataract                             |             4                                            4               |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |          +                                                               |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Glomerulosclerosis                   |                                                                          |             
      Nephropathy                          |    2  2     3  2  2  2  2  2     2  1  2  2  3  2  2     2  2  2  1  1  1|             
      Renal Tubule, Degeneration, Granular |                      3              3                                    |             
      Renal Tubule, Pigmentation, Bile     |                                                             2            |             
      Renal Tubule, Regeneration           | 1                                                     1                  |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  A  +  +  +  +  +  +  A  +  M  +  A  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page  94                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 2| 7| 4| 7| 4| 7| 7| 7| 4| 5| 7| 7| 4| 6| 7| 7| 7| 2| 7| 6| 7| 4| 6| 6|             
                             DAY ON TEST   | 7| 7| 0| 0| 3| 6| 3| 3| 3| 6| 4| 3| 2| 6| 7| 3| 3| 3| 7| 3| 8| 3| 6| 3| 7|             
                                           | 5| 5| 1| 6| 1| 3| 1| 1| 1| 3| 2| 1| 2| 2| 4| 4| 4| 4| 6| 4| 1| 1| 2| 8| 6|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Calculus Micro Observation Only      |    X                                                                     |             
      Ectasia                              |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page  95                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 7| 4| 7| 6| 7| 7| 2| 2| 7| 7| 7| 7| 5| 2|              |            |
                             DAY ON TEST   | 3| 6| 7| 3| 3| 3| 3| 6| 3| 7| 3| 3| 7| 7| 3| 3| 3| 3| 6| 7|              |            |
                                           | 0| 2| 6| 1| 0| 0| 0| 2| 0| 7| 4| 4| 5| 6| 4| 1| 1| 1| 6| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  65        |
      Parasite Metazoan                    | 2              2        3                    2                           |     11  2.7|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Parasite Metazoan                    |                                           4        4                     |     15  3.5|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  64        |
      Parasite Metazoan                    |                                     X  X                                 |      3  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  66        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  64        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  62        |
      Peyer's Patch, Hyperplasia           |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis, Focal                   |                                                                          |      3  2.3|
      Atrophy                              |                                                                          |      2  3.0|
      Basophilic Focus                     | X           X  X  X  X  X  X  X  X           X     X                     |     41     |
      Clear Cell Focus                     | X              X              X  X        X     X                        |     14     |
      Developmental Malformation           |             X                                                            |      3     |
      Fatty Change                         |                                                                          |      4  1.5|
      Fibrosis, Focal                      |                            2                                             |      1  2.0|
      Granuloma                            |                   2                                                      |      3  2.7|
      Hepatodiaphragmatic Nodule           |                                                                          |      3     |
      Mixed Cell Focus                     |                                                                          |      1     |
      Necrosis, Focal                      |                                                                          |      1  2.0|
      Thrombosis                           |                            X                                             |      1     |
      Bile Duct, Hyperplasia               |          3        2        4                                             |     19  2.7|
      Lymphatic, Angiectasis, Focal        |                            3                                             |      4  3.3|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +                 +                                                      |  14        |
      Accessory Spleen                     |                                                                          |      1     |
      Cyst                                 |                                                                          |      1     |
      Fibrosis                             |                   2                                                      |      1  2.0|
      Fat, Necrosis                        | 3                                                                        |     10  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  69        |
      Pigmentation, Focal                  |                                                                          |      1  3.0|
      Acinus, Atrophy                      |          3  1  3  2        3  3  2     2        2  2                     |     22  2.2|
      Acinus, Hyperplasia, Focal           |                2                                                         |      1  2.0|
      Artery, Inflammation, Chronic        |                               4                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cyst Epithelial Inclusion            |                               X                                          |      1     |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  96                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 7| 4| 7| 6| 7| 7| 2| 2| 7| 7| 7| 7| 5| 2|              |            |
                             DAY ON TEST   | 3| 6| 7| 3| 3| 3| 3| 6| 3| 7| 3| 3| 7| 7| 3| 3| 3| 3| 6| 7|              |            |
                                           | 0| 2| 6| 1| 0| 0| 0| 2| 0| 7| 4| 4| 5| 6| 4| 1| 1| 1| 6| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  68        |
      Erosion                              |                                                                          |      3  3.3|
      Hyperplasia, Lymphoid                |                                                                          |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       | 1  2           2     3  1  2  3  1        1  3     3  1                  |     49  1.9|
      Inflammation, Chronic, Focal         |       1                             1  1                                 |      5  1.2|
      Mineralization                       |                               1                                          |      1  1.0|
      Artery, Inflammation, Chronic        |                               2                                          |      1  2.0|
      Atrium, Thrombosis                   |                                                                          |      3     |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cytoplasmic Alteration, Focal        |                                                                          |      1  3.0|
      Hyperplasia                          |                                                                          |      2  2.0|
      Vacuolization Cytoplasmic            |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hyperplasia, Focal                   |             1     1     1                    1                           |     17  1.5|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Hyperplasia, Focal                   |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Pars Distalis, Cyst                  |                                              X                           |      3     |
      Pars Distalis, Hyperplasia, Focal    | 2  2              2  2                                                   |     17  2.0|
      Pars Intermedia, Hyperplasia, Focal  |                               3                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      C-Cell, Hyperplasia                  |             1  1        2                                                |      8  2.0|
      Follicle, Cyst                       |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Depletion Cellular                   |          4                                                               |      2  3.5|
      Spermatocele                         |             X                                                            |      1     |
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  97                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 7| 4| 7| 6| 7| 7| 2| 2| 7| 7| 7| 7| 5| 2|              |            |
                             DAY ON TEST   | 3| 6| 7| 3| 3| 3| 3| 6| 3| 7| 3| 3| 7| 7| 3| 3| 3| 3| 6| 7|              |            |
                                           | 0| 2| 6| 1| 0| 0| 0| 2| 0| 7| 4| 4| 5| 6| 4| 1| 1| 1| 6| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Cyst                                 |                                                                          |      2     |
      Ectasia                              |                                                                          |      1  3.0|
      Inflammation, Acute                  |                                                                          |      1  3.0|
      Inflammation, Chronic, Focal         |       2                                1                                 |      8  2.1|
      Inflammation, Chronic                |    2                 3                                                   |     11  2.2|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Atrophy                              |          3                                                               |     12  2.8|
      Congestion                           |                3                                                         |      1  3.0|
      Dilatation                           |                                                                          |      1  3.0|
      Inflammation, Acute                  |                      2           2                                       |      2  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Atrophy                              |          4  4  3  4     3  4  4           3  2  3  3  3                  |     38  3.4|
      Cyst                                 |                                                                          |      1     |
      Dilatation                           | 4                                                                        |      2  3.5|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Bilateral, Interstitial Cell,        |                                                                          |            |
          Hyperplasia                      |    3                                                                     |      5  2.4|
      Interstitial Cell, Hyperplasia       |                               4                                          |      2  3.0|
      Seminiferous Tubule, Atrophy         |                3                                                         |      2  3.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Granuloma                            |                                                                          |      1  4.0|
      Hyperplasia                          |          4                 4                                             |     23  3.1|
      Myelofibrosis                        |                                                                          |      2  1.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                         +  +  +                                          |  16        |
      Lumbar, Lymphatic, Angiectasis       |                                                                          |      1  3.0|
      Mediastinal, Congestion              |                                                                          |      1  2.0|
      Mediastinal, Lymphatic, Angiectasis  |                               3                                          |      3  3.3|
      Pancreatic, Lymphatic, Angiectasis   |                         2                                                |      4  3.0|
      Renal, Pigmentation                  |                                                                          |      1  4.0|
      Renal, Lymphatic, Angiectasis        |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Angiectasis                          |                               2                       3                  |      4  2.5|
      Depletion Lymphoid                   |                                                                          |      1  3.0|
      Lymphatic, Angiectasis               |          3                                                               |      2  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Angiectasis                          |                               4                                          |      2  4.0|
      Depletion Lymphoid                   |                                                                          |      1  4.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  98                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 7| 4| 7| 6| 7| 7| 2| 2| 7| 7| 7| 7| 5| 2|              |            |
                             DAY ON TEST   | 3| 6| 7| 3| 3| 3| 3| 6| 3| 7| 3| 3| 7| 7| 3| 3| 3| 3| 6| 7|              |            |
                                           | 0| 2| 6| 1| 0| 0| 0| 2| 0| 7| 4| 4| 5| 6| 4| 1| 1| 1| 6| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Giant Cell                           |       1                             1  1                 2               |     10  1.5|
      Hyperplasia, Lymphoid                |                                                                          |      1  3.0|
      Lymphatic, Angiectasis               |                   4                                                      |      3  4.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Congestion                           |                                                                          |      1  4.0|
      Depletion Lymphoid                   |                                                       3                  |      6  3.3|
      Fibrosis                             |          3                 4     2                                       |      9  2.9|
      Hematopoietic Cell Proliferation     |                                                                          |      1  2.0|
      Capsule, Fibrosis                    |                                           2                              |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +               |  67        |
      Cyst                                 |                            X                                             |      2     |
      Depletion Lymphoid                   |                                                                          |      2  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  +  +  M  +  M  +  I  +  M  +  M  +  M  +  M  +  +  +  +               |  53        |
      Lactation                            |                         1                       2                        |     12  1.3|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  68        |
      Abscess                              |                                                                          |      1  3.0|
      Fibrosis, Focal                      |             4                                                            |      1  4.0|
      Ulcer                                |    4                                                                     |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperostosis                         |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                   +                       +                              |   6        |
      Fibrosis                             |                   2                       2                              |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                                          |   1        |
      Degeneration                         |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
      Degeneration                         |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Granuloma                            |                                                                          |      3  2.0|
      Peribronchial, Inflammation, Chronic |       2                                2                 2               |      9  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page  99                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 2| 7| 7| 7| 7| 4| 7| 6| 7| 7| 2| 2| 7| 7| 7| 7| 5| 2|              |            |
                             DAY ON TEST   | 3| 6| 7| 3| 3| 3| 3| 6| 3| 7| 3| 3| 7| 7| 3| 3| 3| 3| 6| 7|              |            |
                                           | 0| 2| 6| 1| 0| 0| 0| 2| 0| 7| 4| 4| 5| 6| 4| 1| 1| 1| 6| 5|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Fungus                               |          4     3              4  4                 2  4                  |     16  3.5|
      Hyperkeratosis                       |                                                                          |      1  4.0|
      Inflammation, Acute                  |                                                                          |      1  1.0|
      Inflammation, Chronic, Focal         |       2                             2  2                 2               |     10  1.8|
      Inflammation, Chronic                |    2                 2                       4                           |     13  2.2|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   3        |
      Cataract                             |                                                                          |      3  3.3|
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Glomerulosclerosis                   |                                                                          |      1  3.0|
      Nephropathy                          | 2     1  2  1  2  2  2  4  2  4  2        2  2  4  2  1  1               |     59  1.8|
      Renal Tubule, Degeneration, Granular |                                                                          |      2  3.0|
      Renal Tubule, Pigmentation, Bile     |                            3                                             |      5  3.2|
      Renal Tubule, Regeneration           |                                     1  1                                 |      6  1.2|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +               |  63        |
      Calculus Micro Observation Only      | X     X                                                                  |      3     |
      Ectasia                              |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  3.0|
      Inflammation, Chronic, Focal         |                      2                                                   |      1  2.0|
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 100                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 3| 7| 2| 7| 1| 4| 7| 2| 4| 7| 4| 7| 7| 4| 4| 6| 7| 4| 3| 7| 4| 4| 7|             
                             DAY ON TEST   | 5| 1| 8| 3| 7| 2| 8| 6| 2| 7| 6| 3| 3| 3| 3| 6| 6| 8| 3| 6| 5| 3| 6| 6| 3|             
                                           | 3| 8| 6| 0| 5| 9| 7| 3| 9| 6| 2| 0| 9| 0| 0| 2| 2| 2| 0| 2| 7| 0| 2| 2| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  A  +  +  +  A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |             X                       4        3                       2   |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |             X                       3  4        4                        |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  A  +  +  +  A  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Parasite Metazoan                    |                      2     X     2                                       |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  A  +  +  A  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                          |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |                                                                          |             
      Basophilic Focus                     | X        X     X     X           X     X  X        X           X        X|             
      Clear Cell Focus                     |                                                       X                 X|             
      Developmental Malformation           |                                        X                                 |             
      Eosinophilic Focus                   |                                                                X         |             
      Fatty Change                         |                                                                          |             
      Granuloma                            |                                                                          |             
      Hepatodiaphragmatic Nodule           | X                                                                       X|             
      Mixed Cell Focus                     |                                        X                                 |             
      Necrosis, Focal                      |    3                                                                     |             
      Bile Duct, Hyperplasia               |          3     4        2     1                 2  4     2     3        2|             
      Lymphatic, Angiectasis, Focal        |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               | +  +                                                  +                  |             
      Accessory Spleen                     |                                                                          |             
      Fibrosis                             |                                                       3                  |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Artery, Thrombosis                   |                                                                          |             
      Fat, Necrosis                        |    4                                                  3                  |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis, Focal                     |                                     2                                    |             
      Inflammation, Chronic, Focal         |                                                                          |             
      Acinus, Atrophy                      |          4  2        2  2  1  2  4        2     2  2           4  2  3  2|             
      Artery, Hypertrophy                  |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              | 3                                                                        |             
      Ulcer                                |                                     4                                    |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                           +                              |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 101                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 3| 7| 2| 7| 1| 4| 7| 2| 4| 7| 4| 7| 7| 4| 4| 6| 7| 4| 3| 7| 4| 4| 7|             
                             DAY ON TEST   | 5| 1| 8| 3| 7| 2| 8| 6| 2| 7| 6| 3| 3| 3| 3| 6| 6| 8| 3| 6| 5| 3| 6| 6| 3|             
                                           | 3| 8| 6| 0| 5| 9| 7| 3| 9| 6| 2| 0| 9| 0| 0| 2| 2| 2| 0| 2| 7| 0| 2| 2| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
      Hyperkeratosis, Focal                |                                           3                              |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |          3     2     3  3  2     3     4        2  1  2        2  2  2  2|             
      Hypertrophy                          |                                                                          |             
      Inflammation, Chronic, Focal         |             2                                                            |             
      Mineralization                       |                                  2                                       |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Atrium, Dilatation                   |                                                                          |             
      Atrium, Thrombosis                   |                                                                X         |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                           2                             2|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |          2     2                          2        2  2        1        3|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                         2                                                |             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hemorrhage            |                2                                                         |             
      Pars Distalis, Hyperplasia, Focal    |             2                 2     1                    2           1   |             
      Pars Intermedia, Cyst                |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                      2                                                   |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Depletion Cellular                   |                                        2                                 |             
      Dilatation                           |                                                                          |             
      Fibrosis                             |                                                                         2|             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                                          |             
      Cyst                                 |                                                                          |             
      Ectasia                              |                         4                                                |             
      Inflammation, Chronic, Focal         |             2              2                                             |             
      Inflammation, Chronic                |       2              2        2     1        2  3        2  1     3  3   |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 102                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 3| 7| 2| 7| 1| 4| 7| 2| 4| 7| 4| 7| 7| 4| 4| 6| 7| 4| 3| 7| 4| 4| 7|             
                             DAY ON TEST   | 5| 1| 8| 3| 7| 2| 8| 6| 2| 7| 6| 3| 3| 3| 3| 6| 6| 8| 3| 6| 5| 3| 6| 6| 3|             
                                           | 3| 8| 6| 0| 5| 9| 7| 3| 9| 6| 2| 0| 9| 0| 0| 2| 2| 2| 0| 2| 7| 0| 2| 2| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Metaplasia, Squamous                 |                                                                          |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                    2  3     3  2        4|             
      Hyperplasia, Focal                   |                                                                          |             
      Inflammation, Chronic                |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       2  4     4                 4  3  3  3        4  4     3  4        4|             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |       2                                                                  |             
      Interstitial Cell, Hyperplasia       |                                                                          |             
      Seminiferous Tubule, Atrophy         |          4                                4  4                           |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    3           3        4                                      4         |             
      Myelofibrosis                        |                                                    4                     |             
                                            __________________________________________________________________________|             
   Lymph Node                              |    +                                +                          +         |             
      Mediastinal, Lymphatic, Angiectasis  |                                                                          |             
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |       3           3           2                                          |             
      Infiltration Cellular, Plasma Cell   |                                                             4            |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |                                                                          |             
      Giant Cell                           |             1              1                                             |             
      Lymphatic, Angiectasis               |                                                       3                  |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |       3                                                  2               |             
      Fibrosis                             |                4                       4           4           1         |             
      Hemorrhage                           |                4                                                         |             
      Infarct                              |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Necrosis, Focal                      |    2                                                                     |             
      Pigmentation, Hemosiderin            |       3           4                                                      |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |       4     2              2                                             |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 103                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 3| 7| 2| 7| 1| 4| 7| 2| 4| 7| 4| 7| 7| 4| 4| 6| 7| 4| 3| 7| 4| 4| 7|             
                             DAY ON TEST   | 5| 1| 8| 3| 7| 2| 8| 6| 2| 7| 6| 3| 3| 3| 3| 6| 6| 8| 3| 6| 5| 3| 6| 6| 3|             
                                           | 3| 8| 6| 0| 5| 9| 7| 3| 9| 6| 2| 0| 9| 0| 0| 2| 2| 2| 0| 2| 7| 0| 2| 2| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lymphatic, Angiectasis               |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M|             
      Lactation                            |    2                    2                          3                     |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |                                                                          |             
      Fibrosis, Focal                      |                                                                          |             
      Ulcer                                |                                                                          |             
      Subcutaneous Tissue, Hemorrhage      |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |    2                                               3                     |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                  4                                       |             
      Hemorrhage                           |    3                                                                     |             
      Meninges, Hemorrhage                 |                                                                          |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                  +                                       |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                                                          |             
      Infiltration Cellular, Focal,        |                                                                          |             
          Histiocyte                       |                                                                          |             
      Peribronchial, Inflammation, Chronic |             2              2                                             |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |       4           X     3              4                    4            |             
      Inflammation, Acute                  |       3                                               3     4            |             
      Inflammation, Chronic, Focal         |                            4                                             |             
      Inflammation, Chronic                |                      2        2     2        2  3        2        2  2   |             
      Metaplasia, Squamous                 |             2                                                            |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                  +                                       |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cataract                             |                                                                          |             
      Retina, Degeneration                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 104                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 5| 3| 7| 2| 7| 1| 4| 7| 2| 4| 7| 4| 7| 7| 4| 4| 6| 7| 4| 3| 7| 4| 4| 7|             
                             DAY ON TEST   | 5| 1| 8| 3| 7| 2| 8| 6| 2| 7| 6| 3| 3| 3| 3| 6| 6| 8| 3| 6| 5| 3| 6| 6| 3|             
                                           | 3| 8| 6| 0| 5| 9| 7| 3| 9| 6| 2| 0| 9| 0| 0| 2| 2| 2| 0| 2| 7| 0| 2| 2| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Autolysis                            |    3                                                                     |             
      Cyst                                 |                                                                          |             
      Nephropathy                          | 1  2  1  3     2     1  2     2  3     2  2  1  2  2  3     1  2  1  2  4|             
      Pelvis, Epithelium, Hyperplasia      |                                           2                              |             
      Renal Tubule, Pigmentation, Bile     |                                                                          |             
      Renal Tubule, Regeneration           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  A  A  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 105                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 1| 7| 7| 2| 6| 7| 7| 7| 7| 1| 6| 6| 5| 7| 4| 7| 7| 7| 6| 7| 4| 7| 7| 7|             
                             DAY ON TEST   | 7| 8| 2| 2| 7| 7| 3| 2| 2| 2| 8| 8| 7| 9| 3| 6| 2| 2| 2| 8| 3| 6| 2| 3| 3|             
                                           | 6| 5| 9| 9| 6| 8| 0| 9| 9| 9| 0| 6| 5| 8| 0| 3| 9| 9| 9| 2| 0| 3| 2| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                   4                                3           2        2|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Parasite Metazoan                    |                      4  3                                      2         |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Hyperplasia, Lymphoid                |                3                                                         |             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis                            |                                                                   4      |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis, Focal                   |          3        4     3                                                |             
      Basophilic Focus                     |          X     X     X  X  X     X  X  X  X  X  X  X  X     X     X  X  X|             
      Clear Cell Focus                     |                            X                       X                     |             
      Developmental Malformation           |                               X                                          |             
      Eosinophilic Focus                   |                   X                                X                     |             
      Fatty Change                         |                2                 1        1                              |             
      Granuloma                            |                                                                          |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Bile Duct, Hyperplasia               |          3        3  3  2                 3  1              2     4  2  2|             
      Lymphatic, Angiectasis, Focal        |                      2                 3                             2   |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +                                   +     +  +                    +|             
      Accessory Spleen                     |                                                                          |             
      Fibrosis                             |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                          |             
      Artery, Thrombosis                   |                                                                          |             
      Fat, Necrosis                        |       3                                   4     4  3                    3|             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Autolysis, Focal                     |                                                                          |             
      Inflammation, Chronic, Focal         |                                                                          |             
      Acinus, Atrophy                      |                3                                   2  4     2        2   |             
      Artery, Hypertrophy                  |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                  3                                       |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperkeratosis                       |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                     2                                    |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 106                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 1| 7| 7| 2| 6| 7| 7| 7| 7| 1| 6| 6| 5| 7| 4| 7| 7| 7| 6| 7| 4| 7| 7| 7|             
                             DAY ON TEST   | 7| 8| 2| 2| 7| 7| 3| 2| 2| 2| 8| 8| 7| 9| 3| 6| 2| 2| 2| 8| 3| 6| 2| 3| 3|             
                                           | 6| 5| 9| 9| 6| 8| 0| 9| 9| 9| 0| 6| 5| 8| 0| 3| 9| 9| 9| 2| 0| 3| 2| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
      Hyperkeratosis, Focal                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |       3  2  1  3  2  2  1  1        2  1  2     2     1     2  1     2  4|             
      Hypertrophy                          |                                                                          |             
      Inflammation, Chronic, Focal         | 2                                                                        |             
      Mineralization                       |                                                                          |             
      Artery, Inflammation, Chronic        |                                                                      3   |             
      Atrium, Dilatation                   |    4                                                                     |             
      Atrium, Thrombosis                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration, Focal        |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Focal                   |          2     2  2  2  1           1                    1        4  1  2|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Cyst                  |                                                                          |             
      Pars Distalis, Hemorrhage            |                                                                          |             
      Pars Distalis, Hyperplasia, Focal    |          3  1  2                                3     2                  |             
      Pars Intermedia, Cyst                |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                         4           4              4     2               |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       |                                  +                                       |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       3                                                                  |             
      Depletion Cellular                   |                            3              3                              |             
      Dilatation                           |                                                          3               |             
      Fibrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Abscess                              |                                                       2                  |             
      Cyst                                 |          X                                               X               |             
      Ectasia                              |                                                                          |             
      Inflammation, Chronic, Focal         | 1           2                                                            |             
      Inflammation, Chronic                |    2                                         2                 3        3|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 107                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 1| 7| 7| 2| 6| 7| 7| 7| 7| 1| 6| 6| 5| 7| 4| 7| 7| 7| 6| 7| 4| 7| 7| 7|             
                             DAY ON TEST   | 7| 8| 2| 2| 7| 7| 3| 2| 2| 2| 8| 8| 7| 9| 3| 6| 2| 2| 2| 8| 3| 6| 2| 3| 3|             
                                           | 6| 5| 9| 9| 6| 8| 0| 9| 9| 9| 0| 6| 5| 8| 0| 3| 9| 9| 9| 2| 0| 3| 2| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Metaplasia, Squamous                 |                         4                                                |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       4        3  3        2              3     2        3        3      |             
      Hyperplasia, Focal                   |                                                                          |             
      Inflammation, Chronic                |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       4  2     4  4  4  3  4        2     4     4  2  4  3  4     4  3  4|             
      Dilatation                           |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Bilateral, Interstitial Cell,        |                                                                          |             
          Hyperplasia                      |                                                                          |             
      Interstitial Cell, Hyperplasia       |                                                                          |             
      Seminiferous Tubule, Atrophy         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 1              4     2     4     3  4  4        2        3  2     4      |             
      Myelofibrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                +                 +                                       |             
      Mediastinal, Lymphatic, Angiectasis  |                                  4                                       |             
      Pancreatic, Lymphatic, Angiectasis   |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                  3                                       |             
      Congestion                           |                               2                                          |             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Lymphatic, Angiectasis               |                                                                         3|             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                4                 4                                       |             
      Congestion                           |                               2                                          |             
      Depletion Lymphoid                   |    2                                                                     |             
      Giant Cell                           | 2                                                                        |             
      Lymphatic, Angiectasis               |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Depletion Lymphoid                   |    4                             2  3                 2                  |             
      Fibrosis                             |                   3     1           1  2                          1      |             
      Hemorrhage                           |                                                                          |             
      Infarct                              |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Necrosis, Focal                      |                                                                          |             
      Pigmentation, Hemosiderin            |                               2                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                               3                                          |             
      Depletion Lymphoid                   |             1                                                            |             
 _____________________________________________________________________________________________________________________|             
                                                             Page 108                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 1| 7| 7| 2| 6| 7| 7| 7| 7| 1| 6| 6| 5| 7| 4| 7| 7| 7| 6| 7| 4| 7| 7| 7|             
                             DAY ON TEST   | 7| 8| 2| 2| 7| 7| 3| 2| 2| 2| 8| 8| 7| 9| 3| 6| 2| 2| 2| 8| 3| 6| 2| 3| 3|             
                                           | 6| 5| 9| 9| 6| 8| 0| 9| 9| 9| 0| 6| 5| 8| 0| 3| 9| 9| 9| 2| 0| 3| 2| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Lymphatic, Angiectasis               |                                                                         4|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  M  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +|             
      Lactation                            |                2     2  2        3              2  3     2              2|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |                                  3                                       |             
      Fibrosis, Focal                      |                            4                                             |             
      Ulcer                                |                            2                                             |             
      Subcutaneous Tissue, Hemorrhage      |          3                                                               |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Compression                          |                                     2                                    |             
      Hemorrhage                           |                                        1                                 |             
      Meninges, Hemorrhage                 |                                                                         2|             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage, Focal                    |                                        3                                 |             
      Infiltration Cellular, Focal,        |                                                                          |             
          Histiocyte                       |                3                                                         |             
      Peribronchial, Inflammation, Chronic | 2  2        2                 3                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fungus                               |                4  4                 4        3                           |             
      Inflammation, Acute                  |                            4                 3                    3  2   |             
      Inflammation, Chronic, Focal         | 2           2                                                            |             
      Inflammation, Chronic                |    2     3                    2           3                    2         |             
      Metaplasia, Squamous                 |                               2                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                   +  +  +|             
      Cataract                             |                                                                   2  2  2|             
      Retina, Degeneration                 |                                                                         3|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 109                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 2| 1| 7| 7| 2| 6| 7| 7| 7| 7| 1| 6| 6| 5| 7| 4| 7| 7| 7| 6| 7| 4| 7| 7| 7|             
                             DAY ON TEST   | 7| 8| 2| 2| 7| 7| 3| 2| 2| 2| 8| 8| 7| 9| 3| 6| 2| 2| 2| 8| 3| 6| 2| 3| 3|             
                                           | 6| 5| 9| 9| 6| 8| 0| 9| 9| 9| 0| 6| 5| 8| 0| 3| 9| 9| 9| 2| 0| 3| 2| 0| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    1000 PPM                               | 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Autolysis                            |                                                                          |             
      Cyst                                 |                   X                                                      |             
      Nephropathy                          |       3  3     1  2  2  1  3     2  3  2  2  1  2  1  2  1  2     1  2  4|             
      Pelvis, Epithelium, Hyperplasia      |                                                                          |             
      Renal Tubule, Pigmentation, Bile     |                3                       4                                 |             
      Renal Tubule, Regeneration           | 1                                                                        |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
 _____________________________________________________________________________________________________________________|             
                                                             Page 110                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 4| 5| 2| 7| 2| 7| 7| 2| 6| 7| 7| 2| 7| 2| 7| 7|              |            |
                             DAY ON TEST   | 2| 2| 2| 2| 6| 9| 7| 2| 7| 2| 3| 7| 3| 3| 3| 7| 2| 7| 2| 2|              |            |
                                           | 9| 9| 9| 9| 2| 0| 5| 9| 5| 9| 0| 6| 9| 0| 0| 5| 9| 6| 9| 9|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    1000 PPM                               | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  66        |
      Parasite Metazoan                    |                                                       3                  |      9  2.9|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Parasite Metazoan                    |             2              2     X        4        X                     |     12  3.1|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  63        |
      Hyperplasia, Lymphoid                |                                                                          |      1  3.0|
      Parasite Metazoan                    |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  67        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  65        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  64        |
      Autolysis                            |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Angiectasis, Focal                   |    3  3                                                                  |      5  3.2|
      Basophilic Focus                     | X  X  X  X           X     X  X     X     X     X     X  X               |     39     |
      Clear Cell Focus                     |                            X                          X                  |      6     |
      Developmental Malformation           |                         X        X     X           X  X                  |      7     |
      Eosinophilic Focus                   |    X                                                                     |      4     |
      Fatty Change                         |                3           2                             1               |      6  1.7|
      Granuloma                            | 3                                                                        |      1  3.0|
      Hepatodiaphragmatic Nodule           |                X                                   X                     |      4     |
      Mixed Cell Focus                     |                                                                          |      1     |
      Necrosis, Focal                      |                                                                          |      1  3.0|
      Bile Duct, Hyperplasia               |    2  3                                4                                 |     22  2.6|
      Lymphatic, Angiectasis, Focal        |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +  +     +           +              +                    +               |  14        |
      Accessory Spleen                     |    X                                                                     |      1     |
      Fibrosis                             |                                                                          |      1  3.0|
      Artery, Inflammation, Chronic        | 4                                                                        |      1  4.0|
      Artery, Thrombosis                   | X                                                                        |      1     |
      Fat, Necrosis                        |          3           4              2                    3               |     11  3.3|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +               |  69        |
      Autolysis, Focal                     |                                                                          |      1  2.0|
      Inflammation, Chronic, Focal         |                                                    1                     |      1  1.0|
      Acinus, Atrophy                      |    3     2     3     4              2                                    |     24  2.5|
      Artery, Hypertrophy                  |                               4                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Hyperplasia                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 111                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 4| 5| 2| 7| 2| 7| 7| 2| 6| 7| 7| 2| 7| 2| 7| 7|              |            |
                             DAY ON TEST   | 2| 2| 2| 2| 6| 9| 7| 2| 7| 2| 3| 7| 3| 3| 3| 7| 2| 7| 2| 2|              |            |
                                           | 9| 9| 9| 9| 2| 0| 5| 9| 5| 9| 0| 6| 9| 0| 0| 5| 9| 6| 9| 9|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    1000 PPM                               | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Hyperkeratosis                       |                                        4                                 |      1  4.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Erosion                              |                                        2                                 |      3  2.3|
      Ulcer                                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                                                          |   1        |
      Hyperkeratosis, Focal                |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Cardiomyopathy                       | 3  2  2     1        3     4  4  1  2  2  1  1  2        1               |     45  2.1|
      Hypertrophy                          |                                        3                                 |      1  3.0|
      Inflammation, Chronic, Focal         |                   1                                                      |      3  1.7|
      Mineralization                       |                                                                          |      1  2.0|
      Artery, Inflammation, Chronic        |                                                                          |      1  3.0|
      Atrium, Dilatation                   |                         4                                                |      2  4.0|
      Atrium, Thrombosis                   |                                                                          |      1     |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Cytoplasmic Alteration, Focal        |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      Hyperplasia, Focal                   | 1  2  1  3                 3                                             |     22  1.9|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +               |  69        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  +  +  +  +  M  +  M  +  +  +  +  +  +  M  M  +  +  +               |  63        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Pars Distalis, Angiectasis           |                                                                          |      1  2.0|
      Pars Distalis, Cyst                  | X                                                  X                     |      2     |
      Pars Distalis, Hemorrhage            |                                                                          |      1  2.0|
      Pars Distalis, Hyperplasia, Focal    |             2              2  2  2  3                    2               |     16  2.0|
      Pars Intermedia, Cyst                |                                                       X                  |      1     |
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  69        |
      C-Cell, Hyperplasia                  |       2  3                                                               |      7  3.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
 __________________________________________________________________________________________________________________________________ 
  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        
                                                             Page 112                                                               
NTP Experiment-Test: 05150-01                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                   METHYLPHENIDATE HYDROCHLORIDE                               Date: 04/23/97  
Route: DOSED FEED                                                                                                 Time: 11:13:41  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 4| 5| 2| 7| 2| 7| 7| 2| 6| 7| 7| 2| 7| 2| 7| 7|              |            |
                             DAY ON TEST   | 2| 2| 2| 2| 6| 9| 7| 2| 7| 2| 3| 7| 3| 3| 3| 7| 2| 7| 2| 2|              |            |
                                           | 9| 9| 9| 9| 2| 0| 5| 9| 5| 9| 0| 6| 9| 0| 0| 5| 9| 6| 9| 9|              |      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      O     |
   FISCHER 344 RATS MALE                   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|              |      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|              |      A     |
    1000 PPM                               | 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8|              |      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|              |            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Atrophy                              |                                                                          |      1  3.0|
      Depletion Cellular                   | 3                                               3     2                  |      6  2.7|
      Dilatation                           |                                                                          |      1  3.0|
      Fibrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Abscess                              |       2                    2                                             |      3  2.0|
      Cyst                                 |                                                                          |      2     |
      Ectasia                              | 3                             3                                          |      3  3.3|
      Inflammation, Chronic, Focal         |                   2     2        2           3     2                     |      9  2.0|
      Inflammation, Chronic                |             2                                                            |     15  2.2|
      Metaplasia, Squamous                 |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Atrophy                              |                               3     4  3        3        3               |     18  2.9|
      Hyperplasia, Focal                   |                3                                                         |      1  3.0|
      Inflammation, Chronic                |                3                                                         |      1  3.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Atrophy                              | 4  4     4     3     2        4     4  4  3     4     4  4               |     41  3.5|
      Dilatation                           |       4                    4                                             |      2  4.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +               |  70        |
      Bilateral, Interstitial Cell,        |                                                                          |            |
          Hyperplasia                      |                   2              3           4