National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/1654

TDMS Study 05150-01 Pathology Tables


                                     INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)
                                                   METHLYPHENIDATE HYDROCHLORIDE


NTP Experiment-Test: 05150-01                                                                                     Report: PEIRPT03
Study Type: CHRONIC                                                                                               Date: 05/20/95
Route: DOSED FEED                                                                                                 Time: 09:09:24




       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
































a  Number of animals examined microscopically at site and number of animals with lesion

                                                             Page   1

NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          70           70           70           70                                     
  Scheduled Sacrifice                                 20           20           20           20                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                13           12           10            7                                     
    Natural Death                                      6            6            4            4                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                29           30           36           38                                     
    Moribund Sacrifice                                 1                                      1                                     
    Natural Death                                                   2                                                               
    Dead                                               1                                                                            
  Animals Examined Microscopically                    70           70           70           70                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (70)         (70)         (70)         (69)                                   
      Angiectasis                                                   1 (1%)                    1 (1%)                                
   Intestine Large, Colon                             (67)         (67)         (69)         (69)                                   
      Parasite Metazoan                                8 (12%)      7 (10%)      7 (10%)      4 (6%)                                
   Intestine Large, Rectum                            (69)         (67)         (70)         (70)                                   
      Parasite Metazoan                                7 (10%)      5 (7%)       4 (6%)       6 (9%)                                
   Intestine Large, Cecum                             (66)         (65)         (69)         (68)                                   
      Autolysis                                        1 (2%)                                                                       
      Dilatation                                       1 (2%)                                                                       
      Inflammation, Chronic                                                                   1 (1%)                                
      Parasite Metazoan                                3 (5%)       3 (5%)       5 (7%)       8 (12%)                               
   Intestine Small, Ileum                             (66)         (63)         (67)         (68)                                   
      Abscess                                                                                 1 (1%)                                
      Parasite Metazoan                                                          1 (1%)                                             
   Liver                                              (70)         (70)         (70)         (70)                                   
      Abscess                                          2 (3%)                                                                       
      Angiectasis                                      1 (1%)                    4 (6%)       4 (6%)                                
      Angiectasis, Focal                                                         1 (1%)                                             
      Atrophy                                                       1 (1%)                                                          
      Basophilic Focus                                42 (60%)     48 (69%)     41 (59%)     48 (69%)                               
      Clear Cell Focus                                11 (16%)      8 (11%)      4 (6%)      10 (14%)                               
      Depletion Glycogen                                            1 (1%)                                                          
      Developmental Malformation                       1 (1%)       1 (1%)                                                          
      Eosinophilic Focus                                                         1 (1%)                                             
      Fatty Change                                     8 (11%)      6 (9%)       5 (7%)       7 (10%)                               
      Granuloma                                        3 (4%)       5 (7%)       7 (10%)      8 (11%)                               
      Hemorrhage                                       1 (1%)       1 (1%)                                                          
      Hepatodiaphragmatic Nodule                       7 (10%)      3 (4%)       5 (7%)       6 (9%)                                
      Hepatodiaphragmatic Nodule, Multiple                                                    1 (1%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    2                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Mineralization, Focal                                                                   1 (1%)                                
      Necrosis, Focal                                  1 (1%)       5 (7%)                    1 (1%)                                
      Pigmentation, Bile                               1 (1%)                                                                       
      Bile Duct, Hyperplasia                           4 (6%)       1 (1%)       5 (7%)       1 (1%)                                
   Mesentery                                          (4)          (7)          (9)          (3)                                    
      Accessory Spleen                                                                        1 (33%)                               
      Inflammation, Granulomatous                                   1 (14%)                                                         
      Fat, Necrosis                                    3 (75%)      6 (86%)      8 (89%)      2 (67%)                               
   Pancreas                                           (70)         (69)         (70)         (70)                                   
      Ectopic Liver                                                 2 (3%)                                                          
      Inflammation, Chronic, Focal                                                            2 (3%)                                
      Acinus, Atrophy                                 13 (19%)     11 (16%)     18 (26%)     13 (19%)                               
      Acinus, Hyperplasia, Focal                                    1 (1%)                                                          
      Artery, Inflammation, Chronic                                 1 (1%)                                                          
   Salivary Glands                                    (70)         (70)         (70)         (70)                                   
      Depletion Cellular                               2 (3%)                                                                       
      Hyperplasia                                      1 (1%)                    1 (1%)                                             
      Hypoplasia                                       1 (1%)                                                                       
      Inflammation, Chronic, Focal                                  2 (3%)                                                          
   Stomach, Forestomach                               (70)         (68)         (70)         (70)                                   
      Acanthosis                                                                              1 (1%)                                
      Diverticulum                                                                            1 (1%)                                
      Hyperkeratosis                                                1 (1%)                                                          
      Hyperplasia, Squamous                            2 (3%)                                                                       
      Inflammation, Subacute                                        1 (1%)                                                          
      Ulcer                                            1 (1%)       1 (1%)       1 (1%)                                             
   Stomach, Glandular                                 (70)         (69)         (70)         (70)                                   
      Depletion Cellular                                            1 (1%)       1 (1%)       1 (1%)                                
      Edema, Focal                                                                            1 (1%)                                
      Erosion                                          5 (7%)       8 (12%)      3 (4%)       5 (7%)                                
      Hypoplasia                                       1 (1%)                                                                       
      Ulcer                                                                      1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (70)         (70)         (70)         (70)                                   
      Cardiomyopathy                                  25 (36%)     23 (33%)     24 (34%)     26 (37%)                               
      Dilatation                                       1 (1%)                                 1 (1%)                                
      Inflammation, Chronic, Focal                     2 (3%)       5 (7%)       6 (9%)       4 (6%)                                
      Mineralization                                                                          1 (1%)                                
      Pigmentation                                                  1 (1%)                                                          
      Artery, Mineralization                                                     1 (1%)                                             
      Coronary Artery, Inflammation, Chronic                        1 (1%)                                                          
      Myocardium, Inflammation, Chronic, Focal                      2 (3%)                    1 (1%)                                
      Perivascular, Inflammation                                                              1 (1%)                                
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    3                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (70)         (69)         (70)         (69)                                   
      Atrophy                                                                                 1 (1%)                                
      Congestion                                                                 1 (1%)                                             
      Cytoplasmic Alteration, Focal                    3 (4%)       8 (12%)      8 (11%)      3 (4%)                                
      Hyperplasia, Focal                               1 (1%)                    3 (4%)                                             
      Mineralization, Focal                                                                   1 (1%)                                
      Vacuolization Cytoplasmic                        3 (4%)                    2 (3%)       2 (3%)                                
   Adrenal Medulla                                    (70)         (69)         (70)         (70)                                   
      Fibrosis                                                      1 (1%)                                                          
      Hyperplasia, Focal                               7 (10%)      4 (6%)       3 (4%)       2 (3%)                                
      Necrosis                                                                                1 (1%)                                
   Islets, Pancreatic                                 (70)         (69)         (70)         (70)                                   
      Hyperplasia                                                   1 (1%)                                                          
      Hypoplasia                                                    2 (3%)       2 (3%)       4 (6%)                                
   Parathyroid Gland                                  (67)         (66)         (65)         (61)                                   
      Hyperplasia                                                   1 (2%)                                                          
      Hyperplasia, Focal                               2 (3%)       1 (2%)                                                          
   Pituitary Gland                                    (70)         (69)         (69)         (67)                                   
      Hemorrhage                                       1 (1%)       1 (1%)                                                          
      Pars Distalis, Angiectasis                       5 (7%)       3 (4%)       2 (3%)       2 (3%)                                
      Pars Distalis, Angiectasis, Focal                1 (1%)                                                                       
      Pars Distalis, Cyst                             11 (16%)      7 (10%)      7 (10%)      8 (12%)                               
      Pars Distalis, Hyperplasia                       2 (3%)                                 1 (1%)                                
      Pars Distalis, Hyperplasia, Focal               14 (20%)     16 (23%)     12 (17%)     11 (16%)                               
   Thyroid Gland                                      (70)         (70)         (70)         (70)                                   
      Inflammation, Chronic, Focal                                                            1 (1%)                                
      C-Cell, Hyperplasia                             14 (20%)     12 (17%)     14 (20%)     12 (17%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (65)         (68)         (69)         (69)                                   
      Abscess                                                       4 (6%)                                                          
      Cyst                                             4 (6%)       4 (6%)       1 (1%)       3 (4%)                                
      Depletion Cellular                                            2 (3%)                                                          
      Dilatation                                      10 (15%)      4 (6%)       5 (7%)       9 (13%)                               
      Inflammation, Acute                              4 (6%)       2 (3%)       3 (4%)       2 (3%)                                
      Inflammation, Chronic                           13 (20%)      8 (12%)     11 (16%)     11 (16%)                               
      Inflammation, Chronic, Focal                     6 (9%)       8 (12%)      9 (13%)      8 (12%)                               
   Ovary                                              (70)         (70)         (70)         (70)                                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    4                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Angiectasis                                                                1 (1%)       1 (1%)                                
      Atrophy                                                                                 1 (1%)                                
      Cyst                                             1 (1%)                    6 (9%)       2 (3%)                                
      Inflammation, Chronic, Focal                     1 (1%)                                                                       
   Uterus                                             (70)         (70)         (70)         (70)                                   
      Abscess                                          1 (1%)                                                                       
      Angiectasis                                                                1 (1%)       1 (1%)                                
      Atrophy                                                                    1 (1%)       2 (3%)                                
      Cyst                                                                                    2 (3%)                                
      Dilatation                                       7 (10%)      6 (9%)      10 (14%)      6 (9%)                                
      Thrombosis                                                    2 (3%)       1 (1%)                                             
      Endometrium, Cyst                                1 (1%)       1 (1%)                    1 (1%)                                
      Endometrium, Fibrosis                            1 (1%)                    2 (3%)                                             
      Endometrium, Hyperplasia, Cystic                 2 (3%)                    1 (1%)                                             
   Vagina                                             (1)          (1)          (4)          (1)                                    
      Dilatation                                       1 (100%)                  1 (25%)                                            
      Exudate                                                       1 (100%)     1 (25%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Blood                                              (2)                       (1)          (1)                                    
      Bacterium                                                                               1 (100%)                              
      Hypochromasia                                                              1 (100%)                                           
   Bone Marrow                                        (70)         (70)         (70)         (70)                                   
      Hyperplasia                                     17 (24%)     11 (16%)     15 (21%)     12 (17%)                               
      Myelofibrosis                                                 3 (4%)       1 (1%)       2 (3%)                                
   Lymph Node                                         (8)          (6)          (12)         (8)                                    
      Inguinal, Congestion                                                                    1 (13%)                               
      Lumbar, Congestion                                                                      1 (13%)                               
      Lumbar, Hyperplasia                                                        1 (8%)                                             
      Mediastinal, Angiectasis                                      1 (17%)      1 (8%)                                             
      Mediastinal, Congestion                          1 (13%)                   2 (17%)      1 (13%)                               
      Mediastinal, Hematopoietic Cell Proliferation                              1 (8%)                                             
      Mediastinal, Lymphatic, Angiectasis                                        1 (8%)                                             
      Pancreatic, Angiectasis                                       1 (17%)                   1 (13%)                               
      Pancreatic, Congestion                           1 (13%)                                                                      
      Pancreatic, Giant Cell                                                                  2 (25%)                               
      Pancreatic, Granuloma                                                      1 (8%)                                             
      Pancreatic, Infiltration Cellular, Histiocyte                                           1 (13%)                               
      Pancreatic, Pigmentation, Hemosiderin                                                   2 (25%)                               
      Pancreatic, Lymphatic, Angiectasis                                         1 (8%)       2 (25%)                               
   Lymph Node, Mandibular                             (70)         (70)         (70)         (69)                                   
      Congestion                                       1 (1%)       1 (1%)       1 (1%)       3 (4%)                                
      Cyst                                                          1 (1%)                                                          
      Giant Cell                                       1 (1%)       1 (1%)       1 (1%)                                             
      Infiltration Cellular, Plasma Cell               1 (1%)                    1 (1%)       1 (1%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    5                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Infiltration Cellular, Histiocyte                1 (1%)                                 1 (1%)                                
      Inflammation, Acute                                           1 (1%)                                                          
      Lymphatic, Angiectasis                                                     1 (1%)       2 (3%)                                
   Lymph Node, Mesenteric                             (70)         (69)         (68)         (70)                                   
      Congestion                                       3 (4%)       1 (1%)       3 (4%)       4 (6%)                                
      Depletion Lymphoid                               1 (1%)                                 1 (1%)                                
      Giant Cell                                      10 (14%)     10 (14%)      8 (12%)     10 (14%)                               
      Granuloma                                        1 (1%)                                 1 (1%)                                
   Spleen                                             (70)         (69)         (70)         (70)                                   
      Autolysis                                        1 (1%)                                                                       
      Congestion                                       1 (1%)                                                                       
      Depletion Lymphoid                               4 (6%)       1 (1%)       6 (9%)       9 (13%)                               
      Fibrosis, Focal                                  1 (1%)       1 (1%)       3 (4%)       1 (1%)                                
      Granuloma                                        1 (1%)                    1 (1%)                                             
      Hematopoietic Cell Proliferation                 4 (6%)       2 (3%)       4 (6%)       3 (4%)                                
      Infarct                                          1 (1%)                    1 (1%)                                             
      Necrosis, Focal                                               1 (1%)                                                          
      Pigmentation, Hemosiderin                        1 (1%)                                                                       
      Capsule, Fibrosis                                1 (1%)                                 1 (1%)                                
   Thymus                                             (68)         (68)         (70)         (65)                                   
      Cyst                                                                                    3 (5%)                                
      Depletion Lymphoid                               2 (3%)       2 (3%)       1 (1%)       1 (2%)                                
      Hyperplasia                                                                1 (1%)                                             
      Lymphatic, Angiectasis                                        1 (1%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (69)         (69)         (66)         (70)                                   
      Galactocele                                      9 (13%)      5 (7%)       2 (3%)       1 (1%)                                
      Galactocele, Multiple                            1 (1%)       1 (1%)                                                          
      Lactation                                       35 (51%)     36 (52%)     27 (41%)     25 (36%)                               
   Skin                                               (70)         (70)         (69)         (70)                                   
      Acanthosis                                                    1 (1%)                                                          
      Cyst Epithelial Inclusion                                     1 (1%)                                                          
      Fibrosis                                                                   1 (1%)                                             
      Hyperkeratosis                                   1 (1%)                    1 (1%)                                             
      Perivascular, Inflammation, Chronic                                        1 (1%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (70)         (70)         (70)         (70)                                   
      Hyperostosis                                     6 (9%)       9 (13%)     12 (17%)      8 (11%)                               
   Skeletal Muscle                                    (1)          (1)          (1)                                                 
      Ectopic Tissue                                   1 (100%)                  1 (100%)                                           
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    6                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (70)         (70)         (69)         (70)                                   
      Abscess                                                                                 1 (1%)                                
      Compression                                      4 (6%)       6 (9%)       4 (6%)       4 (6%)                                
      Congestion                                       1 (1%)                                                                       
      Hemorrhage                                       1 (1%)       4 (6%)       2 (3%)       4 (6%)                                
      Capillary, Inflammation, Chronic                                                        2 (3%)                                
      Choroid Plexus, Inflammation, Chronic                                                   1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (70)         (70)         (70)         (70)                                   
      Angiectasis                                                   2 (3%)       2 (3%)                                             
      Congestion                                                                 1 (1%)                                             
      Emphysema, Focal                                                           1 (1%)                                             
      Granuloma                                        1 (1%)                                                                       
      Hemorrhage, Focal                                                          1 (1%)                                             
      Mineralization, Focal                                                                   1 (1%)                                
      Necrosis, Focal                                  3 (4%)                                                                       
      Alveolar Epithelium, Metaplasia                  2 (3%)                    1 (1%)       1 (1%)                                
      Peribronchial, Inflammation, Chronic            10 (14%)     10 (14%)      9 (13%)     10 (14%)                               
      Pleura, Fibrosis, Focal                                                    1 (1%)                                             
   Nose                                               (70)         (70)         (69)         (70)                                   
      Fungus                                           4 (6%)       4 (6%)       3 (4%)       3 (4%)                                
      Inflammation, Acute                              2 (3%)       1 (1%)       5 (7%)      10 (14%)                               
      Inflammation, Chronic                           10 (14%)     12 (17%)     16 (23%)     14 (20%)                               
      Inflammation, Chronic, Focal                    10 (14%)     10 (14%)      9 (13%)      8 (11%)                               
      Metaplasia, Squamous                             3 (4%)       1 (1%)                    1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (3)          (1)                       (2)                                    
      Cataract                                                      1 (100%)                  1 (50%)                               
      Retina, Degeneration                             1 (33%)                                                                      
   Harderian Gland                                    (2)                                    (2)                                    
      Hyperplasia                                      1 (50%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (70)         (69)         (68)         (69)                                   
      Abscess                                                                                 1 (1%)                                
      Bacterium                                                                               1 (1%)                                
      Cyst                                                          1 (1%)       1 (1%)       1 (1%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    7                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Glomerulosclerosis                                            2 (3%)                    1 (1%)                                
      Mineralization                                  19 (27%)     22 (32%)     20 (29%)     20 (29%)                               
      Mineralization, Focal                            2 (3%)       5 (7%)       7 (10%)                                            
      Nephropathy                                     46 (66%)     49 (71%)     39 (57%)     40 (58%)                               
      Pigmentation                                                                            1 (1%)                                
      Renal Tubule, Degeneration, Granular             1 (1%)       1 (1%)       1 (1%)                                             
      Renal Tubule, Necrosis, Focal                    1 (1%)                                                                       
      Renal Tubule, Pigmentation, Bile                 4 (6%)       6 (9%)       1 (1%)       2 (3%)                                
      Renal Tubule, Regeneration                       1 (1%)       2 (3%)       1 (1%)       2 (3%)                                
   Urinary Bladder                                    (67)         (64)         (67)         (68)                                   
      Hemorrhage                                                                              2 (3%)                                
      Hyperplasia, Focal                                            1 (2%)                                                          
      Inflammation, Chronic, Focal                     1 (1%)                                 1 (1%)                                
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    8                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          70           70           70           70                                     
  Scheduled Sacrifice                                 20           20           20           19                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                14            9            7            9                                     
    Natural Death                                      8            7            9            8                                     
    Accidently Killed                                               1                                                               
  Survivors                                                                                                                         
    Terminal Sacrifice                                28           33           34           33                                     
    Natural Death                                                                             1                                     
  Animals Examined Microscopically                    70           70           70           70                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (66)         (66)         (65)         (66)                                   
      Parasite Metazoan                                8 (12%)      8 (12%)     11 (17%)      9 (14%)                               
   Intestine Large, Rectum                            (68)         (67)         (68)         (69)                                   
      Parasite Metazoan                               10 (15%)     15 (22%)     15 (22%)     12 (17%)                               
   Intestine Large, Cecum                             (66)         (64)         (64)         (63)                                   
      Edema                                            2 (3%)                                                                       
      Hyperplasia, Lymphoid                                         1 (2%)                    1 (2%)                                
      Parasite Metazoan                                3 (5%)       4 (6%)       3 (5%)       3 (5%)                                
   Intestine Small, Jejunum                           (65)         (66)         (64)         (65)                                   
      Hyperplasia, Lymphoid                            1 (2%)       1 (2%)                                                          
   Intestine Small, Ileum                             (66)         (63)         (62)         (64)                                   
      Autolysis                                                                               1 (2%)                                
      Peyer's Patch, Hyperplasia                                                 1 (2%)                                             
   Liver                                              (70)         (70)         (70)         (70)                                   
      Angiectasis, Focal                               2 (3%)       7 (10%)      3 (4%)       5 (7%)                                
      Atrophy                                                       1 (1%)       2 (3%)                                             
      Basophilic Focus                                39 (56%)     46 (66%)     41 (59%)     39 (56%)                               
      Clear Cell Focus                                10 (14%)      8 (11%)     14 (20%)      6 (9%)                                
      Cyst                                             2 (3%)       1 (1%)                                                          
      Developmental Malformation                       3 (4%)       1 (1%)       3 (4%)       7 (10%)                               
      Eosinophilic Focus                               2 (3%)       1 (1%)                    4 (6%)                                
      Fatty Change                                     9 (13%)      5 (7%)       4 (6%)       6 (9%)                                
      Fibrosis, Focal                                  1 (1%)                    1 (1%)                                             
      Granuloma                                                     1 (1%)       3 (4%)       1 (1%)                                
      Hepatodiaphragmatic Nodule                       3 (4%)       3 (4%)       3 (4%)       4 (6%)                                
      Infarct                                                       1 (1%)                                                          
      Mixed Cell Focus                                                           1 (1%)       1 (1%)                                
      Necrosis, Focal                                  3 (4%)       1 (1%)       1 (1%)       1 (1%)                                
      Proliferation                                    1 (1%)                                                                       
      Thrombosis                                                    1 (1%)       1 (1%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    9                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Bile Duct, Dilatation                                         1 (1%)                                                          
      Bile Duct, Hyperplasia                          24 (34%)     31 (44%)     19 (27%)     22 (31%)                               
      Lymphatic, Angiectasis, Focal                    2 (3%)       1 (1%)       4 (6%)       3 (4%)                                
   Mesentery                                          (6)          (7)          (14)         (14)                                   
      Accessory Spleen                                 1 (17%)                   1 (7%)       1 (7%)                                
      Cyst                                                                       1 (7%)                                             
      Fibrosis                                                                   1 (7%)       1 (7%)                                
      Artery, Inflammation, Chronic                                                           1 (7%)                                
      Artery, Thrombosis                                                                      1 (7%)                                
      Fat, Hemorrhage                                  1 (17%)                                                                      
      Fat, Necrosis                                    3 (50%)      5 (71%)     10 (71%)     11 (79%)                               
   Pancreas                                           (69)         (70)         (69)         (69)                                   
      Angiectasis                                                   1 (1%)                                                          
      Autolysis, Focal                                                                        1 (1%)                                
      Inflammation, Chronic, Focal                                                            1 (1%)                                
      Pigmentation, Focal                                                        1 (1%)                                             
      Acinus, Atrophy                                 21 (30%)     28 (40%)     22 (32%)     24 (35%)                               
      Acinus, Hyperplasia, Focal                       2 (3%)       2 (3%)       1 (1%)                                             
      Artery, Hypertrophy                                                                     1 (1%)                                
      Artery, Inflammation, Chronic                                 1 (1%)       2 (3%)                                             
      Vein, Thrombosis                                 1 (1%)                                                                       
   Pharynx                                                         (1)                                                              
      Palate, Inflammation, Chronic                                 1 (100%)                                                        
   Salivary Glands                                    (69)         (70)         (69)         (70)                                   
      Atrophy                                          1 (1%)       1 (1%)                                                          
      Hyperplasia                                                   1 (1%)                    1 (1%)                                
      Thrombosis                                       1 (1%)                                                                       
   Stomach, Forestomach                               (69)         (70)         (70)         (70)                                   
      Cyst Epithelial Inclusion                                                  1 (1%)                                             
      Hyperkeratosis                                   1 (1%)                                 1 (1%)                                
      Inflammation, Chronic, Focal                                  1 (1%)                                                          
      Ulcer                                            3 (4%)       1 (1%)                                                          
   Stomach, Glandular                                 (68)         (70)         (68)         (70)                                   
      Erosion                                          8 (12%)      5 (7%)       3 (4%)       3 (4%)                                
      Hyperplasia, Lymphoid                            4 (6%)       2 (3%)       2 (3%)                                             
      Ulcer                                                                                   1 (1%)                                
      Mucosa, Inflammation, Acute                      1 (1%)                                                                       
      Submucosa, Fibrosis                                           1 (1%)                                                          
   Tongue                                                                                    (1)                                    
      Hyperkeratosis, Focal                                                                   1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   10                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (70)         (70)         (70)         (70)                                   
      Cardiomyopathy                                  56 (80%)     50 (71%)     49 (70%)     45 (64%)                               
      Hypertrophy                                                                             1 (1%)                                
      Inflammation, Chronic, Focal                     2 (3%)       6 (9%)       5 (7%)       3 (4%)                                
      Mineralization                                   4 (6%)                    1 (1%)       1 (1%)                                
      Artery, Inflammation, Chronic                    1 (1%)       1 (1%)       1 (1%)       1 (1%)                                
      Atrium, Dilatation                               1 (1%)       1 (1%)                    2 (3%)                                
      Atrium, Thrombosis                               6 (9%)                    3 (4%)       1 (1%)                                
      Ventricle, Dilatation                                         1 (1%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (70)         (69)         (69)         (69)                                   
      Cytoplasmic Alteration                           1 (1%)                                                                       
      Cytoplasmic Alteration, Focal                    2 (3%)       4 (6%)       1 (1%)       2 (3%)                                
      Hyperplasia                                                                2 (3%)                                             
      Hyperplasia, Focal                                            1 (1%)                                                          
      Hypertrophy                                      1 (1%)                                                                       
      Vacuolization Cytoplasmic                        3 (4%)       2 (3%)       1 (1%)                                             
   Adrenal Medulla                                    (69)         (68)         (69)         (69)                                   
      Hemorrhage                                       1 (1%)       1 (1%)                                                          
      Hyperplasia, Focal                              16 (23%)     12 (18%)     17 (25%)     22 (32%)                               
   Islets, Pancreatic                                 (69)         (70)         (70)         (69)                                   
      Hyperplasia                                      4 (6%)                    1 (1%)                                             
   Parathyroid Gland                                  (67)         (66)         (68)         (63)                                   
      Ectopic Thymus                                   1 (1%)                                                                       
      Hyperplasia, Focal                               2 (3%)       1 (2%)       1 (1%)                                             
   Pituitary Gland                                    (68)         (69)         (68)         (70)                                   
      Pars Distalis, Angiectasis                       1 (1%)       2 (3%)                    1 (1%)                                
      Pars Distalis, Cyst                              1 (1%)       3 (4%)       3 (4%)       2 (3%)                                
      Pars Distalis, Hemorrhage                                     1 (1%)                    1 (1%)                                
      Pars Distalis, Hyperplasia, Focal               10 (15%)     14 (20%)     17 (25%)     16 (23%)                               
      Pars Distalis, Inflammation, Chronic, Focal                   1 (1%)                                                          
      Pars Intermedia, Cyst                            1 (1%)                                 1 (1%)                                
      Pars Intermedia, Hyperplasia, Focal                                        1 (1%)                                             
   Thyroid Gland                                      (70)         (69)         (70)         (69)                                   
      Ultimobranchial Cyst                                          1 (1%)                                                          
      C-Cell, Hyperplasia                              5 (7%)       6 (9%)       8 (11%)      7 (10%)                               
      Follicle, Cyst                                                2 (3%)       1 (1%)                                             
____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   11                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (70)         (69)         (70)         (70)                                   
      Atrophy                                                                                 1 (1%)                                
      Depletion Cellular                               2 (3%)       2 (3%)       2 (3%)       6 (9%)                                
      Dilatation                                                                              1 (1%)                                
      Fibrosis                                                                                1 (1%)                                
      Spermatocele                                                               1 (1%)                                             
   Preputial Gland                                    (70)         (67)         (70)         (70)                                   
      Abscess                                          7 (10%)      4 (6%)                    3 (4%)                                
      Cyst                                             4 (6%)       5 (7%)       2 (3%)       2 (3%)                                
      Ectasia                                          5 (7%)       2 (3%)       1 (1%)       3 (4%)                                
      Hyperplasia                                      1 (1%)                                                                       
      Inflammation, Acute                                           5 (7%)       1 (1%)                                             
      Inflammation, Chronic                           17 (24%)     11 (16%)     11 (16%)     15 (21%)                               
      Inflammation, Chronic, Focal                     8 (11%)      8 (12%)      8 (11%)      9 (13%)                               
      Metaplasia, Squamous                                                                    1 (1%)                                
   Prostate                                           (69)         (70)         (69)         (70)                                   
      Atrophy                                         18 (26%)     11 (16%)     12 (17%)     18 (26%)                               
      Congestion                                                                 1 (1%)                                             
      Dilatation                                       2 (3%)       1 (1%)       1 (1%)                                             
      Hyperplasia, Focal                                                                      1 (1%)                                
      Inflammation, Acute                              1 (1%)                    2 (3%)                                             
      Inflammation, Chronic                            1 (1%)                                 1 (1%)                                
      Inflammation, Focal                                           1 (1%)                                                          
   Seminal Vesicle                                    (68)         (70)         (69)         (70)                                   
      Atrophy                                         36 (53%)     36 (51%)     38 (55%)     41 (59%)                               
      Cyst                                                                       1 (1%)                                             
      Dilatation                                       1 (1%)       3 (4%)       2 (3%)       2 (3%)                                
   Testes                                             (70)         (69)         (70)         (70)                                   
      Hemorrhage, Focal                                             1 (1%)                                                          
      Bilateral, Interstitial Cell, Hyperplasia        4 (6%)       1 (1%)       5 (7%)       4 (6%)                                
      Interstitial Cell, Hyperplasia                   1 (1%)       5 (7%)       2 (3%)       1 (1%)                                
      Seminiferous Tubule, Atrophy                     3 (4%)       5 (7%)       2 (3%)       3 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (69)         (70)         (70)         (70)                                   
      Granuloma                                                                  1 (1%)                                             
      Hyperplasia                                     22 (32%)     19 (27%)     23 (33%)     21 (30%)                               
      Myelofibrosis                                    1 (1%)                    2 (3%)       2 (3%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   12                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
   Lymph Node                                         (12)         (19)         (16)         (11)                                   
      Inguinal, Lymphatic, Angiectasis                              1 (5%)                                                          
      Lumbar, Lymphatic, Angiectasis                                             1 (6%)                                             
      Mediastinal, Congestion                          1 (8%)       1 (5%)       1 (6%)                                             
      Mediastinal, Granuloma                                        1 (5%)                                                          
      Mediastinal, Pigmentation                                     1 (5%)                                                          
      Mediastinal, Lymphatic, Angiectasis              4 (33%)      2 (11%)      3 (19%)      2 (18%)                               
      Pancreatic, Hyperplasia, Lymphoid                             1 (5%)                                                          
      Pancreatic, Lymphatic, Angiectasis               2 (17%)      4 (21%)      4 (25%)      2 (18%)                               
      Renal, Pigmentation                                                        1 (6%)                                             
      Renal, Lymphatic, Angiectasis                                              1 (6%)                                             
   Lymph Node, Mandibular                             (68)         (69)         (68)         (70)                                   
      Angiectasis                                      4 (6%)       2 (3%)       4 (6%)       3 (4%)                                
      Congestion                                       1 (1%)       1 (1%)                    4 (6%)                                
      Depletion Lymphoid                                                         1 (1%)                                             
      Infiltration Cellular, Plasma Cell               2 (3%)       1 (1%)                    1 (1%)                                
      Lymphatic, Angiectasis                           1 (1%)                    2 (3%)       1 (1%)                                
   Lymph Node, Mesenteric                             (69)         (70)         (68)         (69)                                   
      Angiectasis                                      5 (7%)       5 (7%)       2 (3%)       3 (4%)                                
      Congestion                                       1 (1%)                                 1 (1%)                                
      Depletion Lymphoid                               1 (1%)       1 (1%)       1 (1%)       1 (1%)                                
      Giant Cell                                       8 (12%)     10 (14%)     10 (15%)      8 (12%)                               
      Hyperplasia, Lymphoid                                                      1 (1%)                                             
      Lymphatic, Angiectasis                           1 (1%)       2 (3%)       3 (4%)       3 (4%)                                
   Spleen                                             (70)         (70)         (70)         (70)                                   
      Congestion                                       1 (1%)       2 (3%)       1 (1%)       1 (1%)                                
      Depletion Lymphoid                               3 (4%)       2 (3%)       6 (9%)       6 (9%)                                
      Fibrosis                                        14 (20%)     17 (24%)      9 (13%)     11 (16%)                               
      Hematopoietic Cell Proliferation                 3 (4%)       2 (3%)       1 (1%)                                             
      Hemorrhage                                                                              1 (1%)                                
      Hypertrophy                                      1 (1%)                                                                       
      Infarct                                          2 (3%)       7 (10%)                   1 (1%)                                
      Inflammation, Acute                                                                     1 (1%)                                
      Necrosis, Focal                                  1 (1%)                                 1 (1%)                                
      Pigmentation, Hemosiderin                                                               3 (4%)                                
      Thrombosis                                       1 (1%)       1 (1%)                                                          
      Capsule, Congestion, Focal                       1 (1%)                                                                       
      Capsule, Fibrosis                                2 (3%)       1 (1%)       1 (1%)                                             
   Thymus                                             (59)         (67)         (67)         (68)                                   
      Congestion                                                                              1 (1%)                                
      Cyst                                                                       2 (3%)                                             
      Depletion Lymphoid                               1 (2%)                    2 (3%)       5 (7%)                                
      Hemorrhage, Focal                                             1 (1%)                                                          
      Hyperplasia, Lymphoid                                         1 (1%)                                                          
      Lymphatic, Angiectasis                                                                  1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   13                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (57)         (53)         (53)         (61)                                   
      Lactation                                       14 (25%)     14 (26%)     12 (23%)     12 (20%)                               
   Skin                                               (70)         (70)         (68)         (70)                                   
      Abscess                                                                    1 (1%)                                             
      Acanthosis                                                    1 (1%)                                                          
      Cyst Epithelial Inclusion                        1 (1%)                                                                       
      Edema                                                                                   1 (1%)                                
      Fibrosis, Focal                                  2 (3%)                    1 (1%)       1 (1%)                                
      Inflammation, Focal, Granulomatous                            1 (1%)                                                          
      Ulcer                                            1 (1%)                    1 (1%)       1 (1%)                                
      Hair Follicle, Cyst                                           1 (1%)                                                          
      Subcutaneous Tissue, Hemorrhage                                                         1 (1%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (69)         (70)         (70)         (70)                                   
      Callus                                           1 (1%)                                                                       
      Hyperostosis                                     5 (7%)       2 (3%)       3 (4%)       3 (4%)                                
      Proliferation                                    1 (1%)                                                                       
   Skeletal Muscle                                    (1)                       (6)                                                 
      Fibrosis                                                                   2 (33%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (70)         (70)         (70)         (70)                                   
      Compression                                      2 (3%)                                 2 (3%)                                
      Hemorrhage                                       1 (1%)       2 (3%)                    3 (4%)                                
      Meninges, Hemorrhage                                                                    1 (1%)                                
   Peripheral Nerve                                   (1)                       (1)                                                 
      Degeneration                                                               1 (100%)                                           
   Spinal Cord                                        (1)                       (1)          (1)                                    
      Degeneration                                                               1 (100%)                                           
      Hemorrhage, Focal                                1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (70)         (70)         (70)         (70)                                   
      Angiectasis                                      3 (4%)                                                                       
      Congestion                                                    1 (1%)                                                          
      Granuloma                                                                  3 (4%)                                             
      Hemorrhage, Focal                                1 (1%)       1 (1%)                    1 (1%)                                
      Hyperplasia, Adenomatous                         1 (1%)                                                                       
      Infiltration Cellular, Focal, Histiocyte         5 (7%)                                 1 (1%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   14                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Peribronchial, Inflammation, Chronic            11 (16%)     10 (14%)      9 (13%)     11 (16%)                               
      Pleura, Inflammation, Chronic, Focal                          1 (1%)                                                          
   Nose                                               (70)         (69)         (69)         (70)                                   
      Fungus                                          18 (26%)     18 (26%)     16 (23%)     15 (21%)                               
      Hyperkeratosis                                   1 (1%)       1 (1%)       1 (1%)                                             
      Hyperplasia, Basal Cell                          2 (3%)                                                                       
      Inflammation, Acute                              4 (6%)       9 (13%)      1 (1%)       9 (13%)                               
      Inflammation, Chronic                           10 (14%)      7 (10%)     13 (19%)     15 (21%)                               
      Inflammation, Chronic, Focal                    10 (14%)     10 (14%)     10 (14%)      7 (10%)                               
      Metaplasia, Squamous                             4 (6%)       1 (1%)                    2 (3%)                                
      Respiratory Epithelium, Necrosis                              1 (1%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)          (3)          (3)          (3)                                    
      Cataract                                                      1 (33%)      3 (100%)     3 (100%)                              
      Retina, Degeneration                             1 (100%)     2 (67%)                   1 (33%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (69)         (70)         (70)         (67)                                   
      Abscess                                          1 (1%)                                                                       
      Autolysis                                                                               1 (1%)                                
      Cyst                                                          2 (3%)                    1 (1%)                                
      Glomerulosclerosis                                            1 (1%)       1 (1%)                                             
      Mineralization                                   1 (1%)                                                                       
      Necrosis, Focal                                  1 (1%)                                                                       
      Nephropathy                                     56 (81%)     57 (81%)     59 (84%)     57 (85%)                               
      Medulla, Casts                                                1 (1%)                                                          
      Papilla, Necrosis                                1 (1%)                                                                       
      Pelvis, Epithelium, Hyperplasia                                                         1 (1%)                                
      Renal Tubule, Degeneration, Granular             2 (3%)       2 (3%)       2 (3%)                                             
      Renal Tubule, Pigmentation, Bile                 3 (4%)       2 (3%)       5 (7%)       4 (6%)                                
      Renal Tubule, Regeneration                       5 (7%)       4 (6%)       6 (9%)       1 (1%)                                
   Ureter                                             (1)                                                                           
      Hyperplasia                                      1 (100%)                                                                     
   Urinary Bladder                                    (63)         (64)         (63)         (64)                                   
      Calculus Micro Observation Only                  5 (8%)       1 (2%)       3 (5%)                                             
      Ectasia                                                                    1 (2%)                                             
      Hemorrhage                                                    1 (2%)       1 (2%)                                             
      Inflammation, Chronic, Focal                                               1 (2%)                                             
      Ulcer                                            1 (2%)                                                                       
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   15                                                              
NTP Experiment-Test: 05150-01         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                   METHLYPHENIDATE HYDROCHLORIDE                               Date: 05/20/95  
Route: DOSED FEED                                                                                                 Time: 09:09:24  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      500 PPM      1000 PPM                                  
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Transitional Epithelium, Hyperplasia             1 (2%)                                                                       
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   16                                                              
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------                                           
NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.