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TDMS Study 55301-04 Pathology Tables

NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96
Route: DOSED WATER                                                                                                Time: 15:53:54

                                                           CORE STUDY




       Facility:  TSI Mason Research

       Chemical CAS #:  110-86-1

       Lock Date:  None

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All




































                                                              Page   1


NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 1| 6| 7| 5| 7| 7| 7| 7| 4| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 6| 2| 2| 2| 2| 2| 2| 1| 2| 2| 5| 7| 2| 5| 2| 2| 2| 2| 7| 2| 2| 2| 2| 2|             
                                           | 9| 2| 9| 9| 9| 9| 9| 9| 1| 9| 5| 1| 0| 9| 4| 9| 9| 9| 9| 6| 9| 9| 9| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    0 PPM                                  | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | +  A  +  +  +  +  +  +  A  +  +  +  A  M  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Peyer's Patch, Hyperplasia, Lymphoid | 3                                                                        |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                                                      X   |             
      Clear Cell Focus                     |                                                    X                     |             
      Eosinophilic Focus                   | X     X                             X              X  X  X     X        X|             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                   2                 2                                   2|             
      Mixed Cell Focus                     |                                              X              X            |             
      Necrosis                             |                2                             1                           |             
      Vacuolization Cytoplasmic, Diffuse   |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |    +     +           +  +  +  +        +                       +         |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation, Chronic Active         |          2                                                               |             
      Fat, Necrosis                        |    4                 4     4  3        4                       4         |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation, Chronic Active         |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1     1        1  1     1     1     1  1  1  1  2  1  1  2  1  2  1  1  2|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ulcer                                |                                                                          |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                                           1                              |             
                                            __________________________________________________________________________|             
   Tooth                                   |                                                                          |             
      Developmental Malformation           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Aorta, Inflammation, Chronic Active  |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |                                     2                                    |             
      Inflammation, Chronic Active         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   2                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 1| 6| 7| 5| 7| 7| 7| 7| 4| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 6| 2| 2| 2| 2| 2| 2| 1| 2| 2| 5| 7| 2| 5| 2| 2| 2| 2| 7| 2| 2| 2| 2| 2|             
                                           | 9| 2| 9| 9| 9| 9| 9| 9| 1| 9| 5| 1| 0| 9| 4| 9| 9| 9| 9| 6| 9| 9| 9| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    0 PPM                                  | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               |                                                 1              3         |             
      Hemorrhage                           |                                                          2               |             
      Hyperplasia                          |                                                                          |             
      Capsule, Hyperplasia                 | 2  1  1  2  1  3     1     1  1     1  1  1  1  2  2  1     1  1  2  2  3|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  M  M  +  +  M  M  +  M  +  M  +  +  M  +  +  M  +  M  +  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  I  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Pars Distalis, Hyperplasia           |                   3                                               2      |             
      Pars Intermedia, Hyperplasia         |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                      4                                                   |             
      Follicle, Cyst                       | 2                       2              1                                 |             
      Follicular Cell, Hyperplasia         |          1  1     1                 1                       1  1     2  1|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2  3  2  3  4  3  3  4  3  3  3  3  4  3  3  3  2  3  3  3  3  3  3  4  3|             
      Cyst                                 |          1  2                                                  2         |             
      Inflammation, Chronic                |       1        1                                                         |             
      Inflammation, Chronic Active         |                                                                          |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |          4           3     2                    2  3  2     2  2     3   |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             2                                                            |             
      Cyst                                 |                4     4                                4                  |             
      Hyperplasia, Cystic                  | 4     4  4  2  4  3  2  2  3  3     4  4  3  4  4  3  3  1  4  4  3  2  4|             
      Inflammation, Chronic Active         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Myeloid Cell, Hyperplasia            |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                +        +     +                          +           +   |             
      Iliac, Hemorrhage                    |                                                                          |             
      Iliac, Hyperplasia, Lymphoid         |                                                                          |             
      Iliac, Pigmentation                  |                                                                          |             
      Mediastinal, Hemorrhage              |                                                          2               |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   3                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 1| 6| 7| 5| 7| 7| 7| 7| 4| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 6| 2| 2| 2| 2| 2| 2| 1| 2| 2| 5| 7| 2| 5| 2| 2| 2| 2| 7| 2| 2| 2| 2| 2|             
                                           | 9| 2| 9| 9| 9| 9| 9| 9| 1| 9| 5| 1| 0| 9| 4| 9| 9| 9| 9| 6| 9| 9| 9| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    0 PPM                                  | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Mediastinal, Inflammation, Chronic   |                                                                          |             
          Active                           |                                                                          |             
      Renal, Hyperplasia, Lymphoid         |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                         3                                                |             
      Hyperplasia, Lymphoid                |                                                                   2      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Hemorrhage                           |                         2                                                |             
      Hyperplasia, Lymphoid                |                                                    2                     |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |       2  3                 2  3     1  1  1  1        4  2        2  1  1|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Inflammation, Chronic Active         |          2                                                               |             
      Pigmentation                         |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|             
      Atrophy                              |    2                                1                 4  1               |             
      Ectopic Parathyroid Gland            |                            2                                             |             
      Hyperplasia, Lymphoid                |                            4                                             |             
      Inflammation, Acute                  |                                                          2               |             
      Necrosis                             |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                    2                     |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |          4                                                               |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperostosis                         |                                                                         2|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                               4                                          |             
      Mineralization                       |    2           2           2  1     1  2  2     2  1  1  1  2  1  1  2  2|             
      Meninges, Inflammation, Chronic      |                                                                          |             
          Active                           |                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    | 1     2  1                          1                                    |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   4                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 1| 6| 7| 5| 7| 7| 7| 7| 4| 7| 7| 7| 7| 7|             
                             DAY ON TEST   | 2| 6| 2| 2| 2| 2| 2| 2| 1| 2| 2| 5| 7| 2| 5| 2| 2| 2| 2| 7| 2| 2| 2| 2| 2|             
                                           | 9| 2| 9| 9| 9| 9| 9| 9| 1| 9| 5| 1| 0| 9| 4| 9| 9| 9| 9| 6| 9| 9| 9| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    0 PPM                                  | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic Active         |                                                                          |             
      Alveolar Epithelium, Hyperplasia     |          1                                2                              |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                                                 3                        |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         | 1        2     1                          2     1     2  2  1  1        1|             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         | 2  1        2  2  1  2                 2     1  1  1     2  1  1  2      |             
      Respiratory Epithelium, Hyperplasia  | 2           2        2     2                    2              1  2      |             
      Respiratory Epithelium, Inflammation,|                                                                          |             
           Chronic Active                  |    2                                                                     |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infarct                              |                                                                          |             
      Infiltration Cellular, Lymphocyte    |          2                 1        1           1                        |             
      Nephropathy                          |          2                                            2                 1|             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |             1        1     1           1     1  1              1  1      |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   5                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 5| 6| 7| 6| 5| 7| 6| 7| 7| 6| 7| 7| 6| 7| 3| 7| 7| 7| 7| 7| 0| 7|            |
                             DAY ON TEST   | 2| 2| 2| 6| 8| 2| 9| 6| 2| 4| 2| 2| 4| 2| 2| 9| 1| 7| 2| 2| 2| 2| 1| 6| 2|            |
                                           | 9| 9| 9| 8| 7| 9| 1| 5| 9| 4| 9| 9| 4| 9| 9| 7| 4| 5| 9| 9| 9| 9| 9| 4| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|      A     |
    0 PPM                                  | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | +  +  +  A  M  +  A  A  +  +  +  +  A  +  +  +  A  +  +  +  +  M  A  A  +|  37        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  M  A  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  A  +  A  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  A  A  +  +  A  +  +  +  +  A  +  +  +  A  +  +  +  +  +  +  A  +|  42        |
      Peyer's Patch, Hyperplasia, Lymphoid |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  A  +  A  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +|  43        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Basophilic Focus                     |                                                                          |      1     |
      Clear Cell Focus                     |                                                                          |      1     |
      Eosinophilic Focus                   |       X              X  X              X  X  X     X     X     X         |     17     |
      Hematopoietic Cell Proliferation     |          2                    3                                          |      2  2.5|
      Hemorrhage                           |                                     3                                    |      1  3.0|
      Infiltration Cellular, Lymphocyte    |                                                    1                     |      4  1.8|
      Mixed Cell Focus                     |             X              X                             X               |      5     |
      Necrosis                             |          2  4                       3                                    |      5  2.4|
      Vacuolization Cytoplasmic, Diffuse   |                                                          2               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +  +  +  +     +  +  +                       +                    +      |  17        |
      Infiltration Cellular, Lymphocyte    |       4                                                                  |      1  4.0|
      Inflammation, Chronic Active         |          2                                                               |      2  2.0|
      Fat, Necrosis                        | 4  4           3  4  4                                            4      |     12  3.8|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |                                     2                                    |      1  2.0|
      Inflammation, Chronic Active         |          2                                                               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    | 1     2        1     1        1  1  2  1  1     1     1     1     1     2|     33  1.2|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Ulcer                                |                            3                                             |      1  3.0|
      Epithelium, Hyperplasia              |                            2                                             |      1  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Necrosis                             |                                     1                                2   |      3  1.3|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                                        +                       +         |   2        |
      Developmental Malformation           |                                        1                       3         |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|  48        |
      Aorta, Inflammation, Chronic Active  |                      3                                                   |      1  3.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page   6                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 5| 6| 7| 6| 5| 7| 6| 7| 7| 6| 7| 7| 6| 7| 3| 7| 7| 7| 7| 7| 0| 7|            |
                             DAY ON TEST   | 2| 2| 2| 6| 8| 2| 9| 6| 2| 4| 2| 2| 4| 2| 2| 9| 1| 7| 2| 2| 2| 2| 1| 6| 2|            |
                                           | 9| 9| 9| 8| 7| 9| 1| 5| 9| 4| 9| 9| 4| 9| 9| 7| 4| 5| 9| 9| 9| 9| 9| 4| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|      A     |
    0 PPM                                  | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cardiomyopathy                       |                                                                          |      1  2.0|
      Inflammation, Chronic Active         |          1                                                               |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Cytoplasmic Alteration               |                                                                          |      2  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hyperplasia                          |                                                       1                  |      1  1.0|
      Capsule, Hyperplasia                 | 2  1  2  2  2  2     1  2  2  3  2  1  2  1  1        2  1  1     1     2|     41  1.6|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |                                                             3            |      1  3.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  M  M  +  M  M  +  M  M  M  +|  31        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Pars Distalis, Hyperplasia           |       1     2                                                     3      |      5  2.2|
      Pars Intermedia, Hyperplasia         |                            2                                             |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      C-Cell, Hyperplasia                  |                                                                          |      1  4.0|
      Follicle, Cyst                       |                                                          3               |      4  2.0|
      Follicular Cell, Hyperplasia         | 2     1                       1                          4  2           1|     14  1.4|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  I  +  +  +  I  +  +  +  +  +|  47        |
      Atrophy                              | 3  3     3  3  3  3  4  4  3     3  3  3  2     3     3     3  3  4  3  3|     45  3.1|
      Cyst                                 |                                                                          |      3  1.7|
      Inflammation, Chronic                |                                                                          |      2  1.0|
      Inflammation, Chronic Active         |    2                                                  1                  |      2  1.5|
      Pigmentation                         |       2                                               2                  |      2  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
      Cyst                                 | 2              3     4           3           3                           |     14  2.7|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Congestion                           |                                                                          |      1  2.0|
      Cyst                                 |                                                                          |      3  4.0|
      Hyperplasia, Cystic                  | 2  2  3     1  3  1  1  4  3  2  3  2  3  2  3        3  4  4  2  2     4|     44  2.9|
      Inflammation, Chronic Active         |          4                                                               |      1  4.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page   7                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 5| 6| 7| 6| 5| 7| 6| 7| 7| 6| 7| 7| 6| 7| 3| 7| 7| 7| 7| 7| 0| 7|            |
                             DAY ON TEST   | 2| 2| 2| 6| 8| 2| 9| 6| 2| 4| 2| 2| 4| 2| 2| 9| 1| 7| 2| 2| 2| 2| 1| 6| 2|            |
                                           | 9| 9| 9| 8| 7| 9| 1| 5| 9| 4| 9| 9| 4| 9| 9| 7| 4| 5| 9| 9| 9| 9| 9| 4| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|      A     |
    0 PPM                                  | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |    3                                                                     |      1  3.0|
      Myeloid Cell, Hyperplasia            |          4                                                               |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              | +        +                          +        +                          +|  10        |
      Iliac, Hemorrhage                    | 2                                                                        |      1  2.0|
      Iliac, Hyperplasia, Lymphoid         | 3                                   4                                   1|      3  2.7|
      Iliac, Pigmentation                  | 2                                                                        |      1  2.0|
      Mediastinal, Hemorrhage              |                                                                          |      1  2.0|
      Mediastinal, Inflammation, Chronic   |                                                                          |            |
          Active                           |          3                                                               |      1  3.0|
      Renal, Hyperplasia, Lymphoid         |                                     4                                    |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Hemorrhage                           |                   2  1                                                   |      3  2.0|
      Hyperplasia, Lymphoid                |                                     3                                    |      2  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Hematopoietic Cell Proliferation     |                                                    2                     |      1  2.0|
      Hemorrhage                           |       1  2  2                                                            |      4  1.8|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hematopoietic Cell Proliferation     | 1  2     4  2  1  4  2        4     4     3        2     2  1  2  3     1|     29  2.1|
      Hyperplasia, Lymphoid                |       2                                                        3         |      2  2.5|
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
      Pigmentation                         |                      2                                                   |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  M  +  +  M  +  +  +  A  +  +  +  M  +  +  +  +|  45        |
      Atrophy                              |    2     4  2     3     3     3                          2               |     11  2.5|
      Ectopic Parathyroid Gland            |                                                                          |      1  2.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  4.0|
      Inflammation, Acute                  |                                                                          |      1  2.0|
      Necrosis                             |                                                                      2   |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Hyperplasia                          |                                                 2                        |      2  2.0|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Inflammation, Chronic Active         |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page   8                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 5| 6| 7| 6| 5| 7| 6| 7| 7| 6| 7| 7| 6| 7| 3| 7| 7| 7| 7| 7| 0| 7|            |
                             DAY ON TEST   | 2| 2| 2| 6| 8| 2| 9| 6| 2| 4| 2| 2| 4| 2| 2| 9| 1| 7| 2| 2| 2| 2| 1| 6| 2|            |
                                           | 9| 9| 9| 8| 7| 9| 1| 5| 9| 4| 9| 9| 4| 9| 9| 7| 4| 5| 9| 9| 9| 9| 9| 4| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|      A     |
    0 PPM                                  | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperostosis                         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                                                                          |      1  4.0|
      Mineralization                       | 1  2        1     2           1           2  1              2           2|     25  1.6|
      Meninges, Inflammation, Chronic      |                                                                          |            |
          Active                           |                   2                                                      |      1  2.0|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                    +                     |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                   3                                                      |      1  3.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      4  1.3|
      Inflammation, Chronic Active         |                         1                                                |      1  1.0|
      Alveolar Epithelium, Hyperplasia     |                      2  2           1                                    |      5  1.6|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                   2                                                      |      2  2.5|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |                            X                                             |      1     |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |             1     2     1     1     2     1  2              1           2|     19  1.4|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         | 1  1  1  1  1        1  1     1  1  1        2  1                        |     27  1.3|
      Respiratory Epithelium, Hyperplasia  | 2                                2  1        2                          1|     12  1.8|
      Respiratory Epithelium, Inflammation,|                                                                          |            |
           Chronic Active                  |    1                       1                                             |      3  1.3|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
      Infarct                              |                               4                                          |      1  4.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      4  1.3|
      Nephropathy                          |                   1           2                                          |      5  1.6|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  A  +  +  A  +  +  +  +  A  +  +  +  A  +  +  +  +  +  +  +  +|  45        |
      Infiltration Cellular, Lymphocyte    |    1  1        1           1  2  1                             1  1      |     16  1.1|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page   9                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 5| 0| 6| 7| 7| 7| 7| 7| 6| 7| 0| 7| 3| 6| 7| 0| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 2| 2| 9| 9| 0| 4| 2| 2| 2| 1| 2| 0| 2| 2| 2| 7| 8| 2| 1| 2| 2| 2| 2| 7| 2|             
                                           | 9| 9| 6| 9| 4| 9| 9| 9| 9| 3| 9| 5| 9| 0| 9| 2| 0| 9| 6| 9| 9| 9| 9| 3| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    125 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | +  +  +  A  A  A  +  +  +  A  +  +  +  +  M  +  A  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  A  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Peyer's Patch, Hyperplasia, Lymphoid |                   2                                                      |             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Clear Cell Focus                     |                                                          X              X|             
      Eosinophilic Focus                   |    X  X  X                          X                    X     X        X|             
      Hematopoietic Cell Proliferation     |                                                 2                        |             
      Mixed Cell Focus                     |                               X                                   X     X|             
      Necrosis                             |                   4                                         4            |             
      Periportal, Vacuolization Cytoplasmic|                                              1                           |             
                                            __________________________________________________________________________|             
   Mesentery                               |          +              +           +           +              +     +  +|             
      Fat, Necrosis                        |                         3           2           4                    4  4|             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                   2                                                      |             
      Acinus, Atrophy                      |                                                 4              3         |             
      Duct, Cyst                           |                                                                3         |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1  1           1  2  2  2  1  1  1  1     3     1  1     1  1     1  1  1|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |       1                                                                  |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                                 2                        |             
      Capsule, Hyperplasia                 | 2        1        2  1  1  1  1  1  1     1     1  2     1  1  1  3  1  1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                           2                              |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  M  M  +  +  +  M  M  M  M  M  +  +  +  M  +  M  +  +  M  +  +  +  M  M|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  M  +  +|             
      Pars Distalis, Angiectasis           |                                                                          |             
      Pars Distalis, Hyperplasia           | 1                                1                          2           3|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  10                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 5| 0| 6| 7| 7| 7| 7| 7| 6| 7| 0| 7| 3| 6| 7| 0| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 2| 2| 9| 9| 0| 4| 2| 2| 2| 1| 2| 0| 2| 2| 2| 7| 8| 2| 1| 2| 2| 2| 2| 7| 2|             
                                           | 9| 9| 6| 9| 4| 9| 9| 9| 9| 3| 9| 5| 9| 0| 9| 2| 0| 9| 6| 9| 9| 9| 9| 3| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    125 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Follicular Cell, Hyperplasia         |                         3  1        2     1        3     4  1     1     2|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  3  2  4     3  3  4  3  3  3  3  3        3  3  3        3  3  3  3  2|             
      Inflammation, Chronic                |                                                             1            |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Cyst                                 |                3        2     4           2  4           1     2         |             
      Periovarian Tissue, Hyperplasia,     |                                                                          |             
           Lymphoid                        |                                                                          |             
                                            __________________________________________________________________________|             
   Oviduct                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hyperplasia, Cystic                  | 2  3  2        1  4  4  2  4  3  3  3     4  2  1  1     2  2  3  4  1  2|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3                                                                        |             
                                            __________________________________________________________________________|             
   Lymph Node                              |          +              +  +                    +              +         |             
      Mediastinal, Hyperplasia, Plasma Cell|                                                 3                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                   4                                                      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |                                     3                                    |             
      Hemorrhage                           |                2                    2                                    |             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       2                                                                  |             
      Hematopoietic Cell Proliferation     | 2  2     3     3  2        2        3     2     4           2  2     3  1|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                   2                                      2               |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       3        2           2     3        2     2  1     1           2   |             
      Necrosis                             |             3                                         1                  |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  11                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 5| 0| 6| 7| 7| 7| 7| 7| 6| 7| 0| 7| 3| 6| 7| 0| 7| 7| 7| 7| 5| 7|             
                             DAY ON TEST   | 2| 2| 9| 9| 0| 4| 2| 2| 2| 1| 2| 0| 2| 2| 2| 7| 8| 2| 1| 2| 2| 2| 2| 7| 2|             
                                           | 9| 9| 6| 9| 4| 9| 9| 9| 9| 3| 9| 5| 9| 0| 9| 2| 0| 9| 6| 9| 9| 9| 9| 3| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2|             
    125 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic Active         |                                                                          |             
      Subcutaneous Tissue, Necrosis        |                                                 2                        |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |                                                 2                       3|             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Mineralization                       |    2  2  2     2           2        2     2  1  1  2     1  2  2     2   |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |             2                                                            |             
      Infiltration Cellular, Lymphocyte    |          1        1                                                      |             
      Alveolar Epithelium, Hyperplasia     |                                     3              2              3      |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         |    1  1        2  2     1  2  1     1     2        2        1     1  2   |             
      Olfactory Epithelium, Necrosis       |                                        1                                 |             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         |    1  1              1           1  1     2     1              2         |             
      Respiratory Epithelium, Hyperplasia  |       1                             1           1  1     1               |             
      Respiratory Epithelium, Necrosis     |                                        1                                 |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infarct                              |                                                                1  1      |             
      Infiltration Cellular, Lymphocyte    |                                                                         2|             
      Nephropathy                          |                         1     1           1     3        1  2            |             
      Renal Tubule, Dilatation             |             2                                                            |             
      Renal Tubule, Regeneration           |                                              1                           |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    1           1                 1        1              1  1     1  1   |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  12                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 5| 7| 6| 7| 7| 7| 6| 7| 7| 7| 1| 7| 7| 7| 7| 7| 4| 7| 7| 7| 7|            |
                             DAY ON TEST   | 0| 2| 2| 7| 5| 2| 7| 2| 2| 2| 4| 2| 2| 2| 7| 1| 2| 2| 2| 2| 1| 2| 2| 2| 2|            |
                                           | 8| 9| 9| 4| 5| 9| 7| 9| 9| 9| 2| 9| 9| 9| 2| 1| 4| 9| 9| 9| 9| 9| 9| 9| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    125 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | A  +  +  +  A  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +  +  +  +  +  +|  40        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Peyer's Patch, Hyperplasia, Lymphoid |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Clear Cell Focus                     |       X              X                                         X         |      5     |
      Eosinophilic Focus                   |       X                       X        X              X        X         |     12     |
      Hematopoietic Cell Proliferation     |                                                                          |      1  2.0|
      Mixed Cell Focus                     |                                                                      X   |      4     |
      Necrosis                             |                                                                          |      2  4.0|
      Periportal, Vacuolization Cytoplasmic|                                                             1            |      2  1.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +           +     +        +                 +  +  +     +     +     +  +|  18        |
      Fat, Necrosis                        |             4              4                 4  4  4     3     2        3|     13  3.5|
                                            __________________________________________________________________________|____________|
   Pancreas                                | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  2.0|
      Acinus, Atrophy                      |                                                                          |      2  3.5|
      Duct, Cyst                           |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |    1  1     2        1     1     1     1     1  1  1  1  1  2  1  1  1  1|     35  1.2|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Necrosis                             |                                           1     2                        |      3  1.3|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hematopoietic Cell Proliferation     |                                                                          |      1  2.0|
      Capsule, Hyperplasia                 | 1  1  1        1  1  1     1  1     1  1           2  1  1     2  1  1  2|     35  1.2|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |                2                                                         |      2  2.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  13                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 5| 7| 6| 7| 7| 7| 6| 7| 7| 7| 1| 7| 7| 7| 7| 7| 4| 7| 7| 7| 7|            |
                             DAY ON TEST   | 0| 2| 2| 7| 5| 2| 7| 2| 2| 2| 4| 2| 2| 2| 7| 1| 2| 2| 2| 2| 1| 2| 2| 2| 2|            |
                                           | 8| 9| 9| 4| 5| 9| 7| 9| 9| 9| 2| 9| 9| 9| 2| 1| 4| 9| 9| 9| 9| 9| 9| 9| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    125 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | M  +  +  M  +  M  +  M  M  +  M  +  +  +  +  +  +  +  +  +  +  M  +  M  M|  29        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  M  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  44        |
      Pars Distalis, Angiectasis           |                                              2                           |      1  2.0|
      Pars Distalis, Hyperplasia           |                                                                          |      4  1.8|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |                            1                                      1     1|      3  1.0|
      Follicular Cell, Hyperplasia         |       1  4           1  2  1     1  4              1  1  1           1  2|     21  1.8|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Atrophy                              | 3  2  3  3     3  3  2  3  2  2  3  3  2     3  3  3  3  3  2  3  3  3  3|     43  2.9|
      Inflammation, Chronic                |    1                                                                     |      2  1.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Angiectasis                          |                                                                      2   |      1  2.0|
      Cyst                                 |                                  1                                2      |      9  2.3|
      Periovarian Tissue, Hyperplasia,     |                                                                          |            |
           Lymphoid                        |                                  2                                       |      1  2.0|
                                            __________________________________________________________________________|____________|
   Oviduct                                 |                               +                                          |   1        |
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |          3     4                                3                        |      3  3.3|
      Hyperplasia, Cystic                  | 1  2  4  4        3  3  1  3  1  1  2  4     1  3  3  2  2  2  4  1  2  3|     43  2.4|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              | +        +        +                 +                    +               |  10        |
      Mediastinal, Hyperplasia, Plasma Cell|                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia, Lymphoid                |                                        2                                 |      2  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  M  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Ectasia                              |                                                                          |      1  3.0|
      Hemorrhage                           |                                                                          |      2  2.0|
      Hyperplasia, Lymphoid                |                                                       4                  |      1  4.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  2.0|
      Hematopoietic Cell Proliferation     |       3  4        3  1     1  3     2        2     1  3  3        3  2  2|     27  2.4|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  14                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 5| 7| 6| 7| 7| 7| 6| 7| 7| 7| 1| 7| 7| 7| 7| 7| 4| 7| 7| 7| 7|            |
                             DAY ON TEST   | 0| 2| 2| 7| 5| 2| 7| 2| 2| 2| 4| 2| 2| 2| 7| 1| 2| 2| 2| 2| 1| 2| 2| 2| 2|            |
                                           | 8| 9| 9| 4| 5| 9| 7| 9| 9| 9| 2| 9| 9| 9| 2| 1| 4| 9| 9| 9| 9| 9| 9| 9| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    125 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Hemorrhage                           | 3                                                                        |      1  3.0|
      Hyperplasia, Lymphoid                |                         1        2                 3                     |      5  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  M  +  M  +  +  +  +  I  +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  +|  44        |
      Atrophy                              |             3     4                                                      |     11  2.3|
      Necrosis                             |                                           2                 2            |      4  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |          4                                                               |      1  4.0|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                 3                        |      1  3.0|
      Subcutaneous Tissue, Necrosis        |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               |                            2                          3        4         |      5  2.8|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |          +                                                               |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |          2                                                               |      1  2.0|
      Infiltration Cellular, Histiocyte    |                                                          2               |      1  2.0|
      Mineralization                       |    1           2  2  2  2  2           1        2  2  1  2     2        1|     27  1.7|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                           2                              |      2  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      2  1.0|
      Alveolar Epithelium, Hyperplasia     |                                                                          |      3  2.7|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |    1  2  3     1        2  2        1        2  1  2  2  2        2     2|     27  1.6|
      Olfactory Epithelium, Necrosis       |                                                                          |      1  1.0|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         | 1              1     2  2  1     1                       1              1|     16  1.3|
      Respiratory Epithelium, Hyperplasia  |    1                       1        2                                    |      8  1.1|
      Respiratory Epithelium, Necrosis     |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  15                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 6| 7| 7| 6| 5| 7| 6| 7| 7| 7| 6| 7| 7| 7| 1| 7| 7| 7| 7| 7| 4| 7| 7| 7| 7|            |
                             DAY ON TEST   | 0| 2| 2| 7| 5| 2| 7| 2| 2| 2| 4| 2| 2| 2| 7| 1| 2| 2| 2| 2| 1| 2| 2| 2| 2|            |
                                           | 8| 9| 9| 4| 5| 9| 7| 9| 9| 9| 2| 9| 9| 9| 2| 1| 4| 9| 9| 9| 9| 9| 9| 9| 9|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    125 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 SPECIAL SENSES SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infarct                              |                                                                          |      2  1.0|
      Infiltration Cellular, Lymphocyte    |                               1                                          |      2  1.5|
      Nephropathy                          |                                                    1  3           1     1|     10  1.5|
      Renal Tubule, Dilatation             |                                                                          |      1  2.0|
      Renal Tubule, Regeneration           |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |          1  2              1  1        1        1  1                    1|     16  1.1|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  16                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 0| 7| 1| 7| 6| 7| 6| 7| 6| 7| 7| 6| 7| 0| 7| 7| 7| 7| 6| 7| 6| 0| 7| 7| 7|             
                             DAY ON TEST   | 4| 2| 7| 2| 3| 2| 9| 2| 9| 2| 0| 8| 2| 0| 2| 2| 2| 2| 4| 2| 9| 3| 2| 2| 2|             
                                           | 0| 9| 5| 9| 3| 9| 6| 7| 7| 9| 0| 4| 9| 3| 9| 9| 9| 9| 2| 9| 9| 3| 3| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    250 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | A  M  +  +  +  +  A  +  A  +  +  A  +  A  +  +  +  +  +  +  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  A  +  +  +  A  +  +  +  +  A  +  +  +  +  +  +  A  A  +  +  +|             
      Edema                                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | A  +  +  +  +  +  +  +  A  +  +  A  +  A  +  +  +  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  +  +  +  +  +  +  A  +  +  A  +  A  +  +  +  +  A  +  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  +  +  A  +  +  +  A  +  +  A  +  A  +  +  +  +  +  +  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Clear Cell Focus                     |                                                                          |             
      Cyst                                 |                                                                          |             
      Eosinophilic Focus                   |          X        X        X  X                             X           X|             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis                             |             3                 2                    4                     |             
      Centrilobular, Degeneration          |                                                                   2      |             
      Midzonal, Vacuolization Cytoplasmic  |                                                                          |             
      Periportal, Vacuolization Cytoplasmic|       1                                                                  |             
                                            __________________________________________________________________________|             
   Mesentery                               |          M  +  +  +  +              +     +  +  +                        |             
      Fat, Necrosis                        |                3  3  2              4     4  4  3                        |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Acinus, Atrophy                      |                                                    3                     |             
      Artery, Inflammation, Chronic        |                                                    2                     |             
      Duct, Cyst                           |                                                    3                     |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    3     2        1     1  1  1     1     1     1  1  1  1  1     1  1  2|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Necrosis                             |                   1                                                      |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Capsule, Hyperplasia                 |    2     2     2  1     1  2  1  1  1     1  1  1  1  1  2  2     1  1  1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Hyperplasia                          |                                           2                              |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  M  +  +  M  +  +  M  +  +  +  M  +  M  M  +  +  M  +  M  M  M  +  M|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  17                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 0| 7| 1| 7| 6| 7| 6| 7| 6| 7| 7| 6| 7| 0| 7| 7| 7| 7| 6| 7| 6| 0| 7| 7| 7|             
                             DAY ON TEST   | 4| 2| 7| 2| 3| 2| 9| 2| 9| 2| 0| 8| 2| 0| 2| 2| 2| 2| 4| 2| 9| 3| 2| 2| 2|             
                                           | 0| 9| 5| 9| 3| 9| 6| 7| 7| 9| 0| 4| 9| 3| 9| 9| 9| 9| 2| 9| 9| 3| 3| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    250 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | M  +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +|             
      Pars Distalis, Hyperplasia           |                            3                                            1|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Follicle, Cyst                       |                                                                          |             
      Follicular Cell, Hyperplasia         |    3     3        2     1  2     2  2        2  3        2           2  3|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Peritoneum                              |             +                                                            |             
      Inflammation, Chronic Active         |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |             +        +                                                   |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +|             
      Atrophy                              |    3     3  3  3  2  4  3  4  3  4  3     3  3  3  3  3     2     3  4  3|             
      Inflammation, Chronic                |                   2                                                      |             
      Inflammation, Chronic Active         |                                              2        3                  |             
      Pigmentation                         |                2                                                         |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  M  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                   4                 2        3                    2     4|             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Cyst                                 |                      4                    4           3           4      |             
      Hyperplasia, Cystic                  |    4     2  3  2  3        4  2  3  1     3  1  2  1     1  2        1  4|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Lymph Node                              |             +                                         +                  |             
      Iliac, Hyperplasia, Lymphoid         |                                                                          |             
      Inguinal, Hyperplasia, Lymphoid      |                                                       4                  |             
      Mediastinal, Hemorrhage              |                                                                          |             
      Mediastinal, Pigmentation            |                                                                          |             
      Renal, Hemorrhage                    |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  A  +  +  +  +  M  +  +  +  +  +  +  +  A  +  +  +|             
      Angiectasis                          |                                           2                              |             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Hematopoietic Cell Proliferation     |    2     2  3  2     3     2        2     1  3  1  3     2        4     3|             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                       4                  |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Atrophy                              |             3  2  2  4        3                       4     2     2      |             
      Ectopic Parathyroid Gland            |                                                                   2      |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  18                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 0| 7| 1| 7| 6| 7| 6| 7| 6| 7| 7| 6| 7| 0| 7| 7| 7| 7| 6| 7| 6| 0| 7| 7| 7|             
                             DAY ON TEST   | 4| 2| 7| 2| 3| 2| 9| 2| 9| 2| 0| 8| 2| 0| 2| 2| 2| 2| 4| 2| 9| 3| 2| 2| 2|             
                                           | 0| 9| 5| 9| 3| 9| 6| 7| 7| 9| 0| 4| 9| 3| 9| 9| 9| 9| 2| 9| 9| 3| 3| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    250 PPM                                | 1| 1| 1| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Necrosis                             | 2     2                                                                  |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                       2                  |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |                   2                                                      |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |             +                                                            |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization                       |                      2  3                          1        2        2  2|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           | 2     2                                2                       3         |             
      Alveolar Epithelium, Hyperplasia     |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         |    2     2  2  2  3  2  2  2     1  1     2  2  2  2     2        1  2  2|             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         |          2                       1                 2                 2  1|             
      Respiratory Epithelium, Hyperplasia  |             1  1  1     1  1     1  1                    1              1|             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infarct                              |                                                             1            |             
      Infiltration Cellular, Lymphocyte    |                                                    1                    4|             
      Nephropathy                          |          1     1     1                       1           1               |             
      Glomerulus, Amyloid Deposition       |                                                                          |             
      Renal Tubule, Dilatation             |       2                                2                                 |             
      Renal Tubule, Pigmentation           |             3                                                            |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    1        1              1  1     1        1  1  1        1           1|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  19                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 7| 6| 7| 6| 6| 7| 7| 7| 5| 7| 5| 6| 7| 6| 7| 7| 4| 7| 7| 7| 6| 5|            |
                             DAY ON TEST   | 0| 5| 0| 2| 9| 2| 5| 3| 2| 2| 2| 8| 2| 0| 2| 2| 4| 2| 1| 1| 2| 2| 2| 7| 6|            |
                                           | 8| 6| 0| 9| 2| 9| 9| 2| 9| 9| 9| 3| 9| 9| 4| 9| 8| 9| 2| 7| 2| 9| 9| 8| 4|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    250 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | A  A  A  +  +  +  +  +  +  +  +  A  +  A  M  +  A  +  +  A  +  +  +  +  A|  33        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  A|  40        |
      Edema                                |                                                             2            |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  A  +  +  +  A  A  +  +  +  +  +  M  +  +  A  +  +  +  +  +  +  +  A|  39        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  A  A|  38        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  A  +  +  +  A  A  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  +  A|  37        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Clear Cell Focus                     |                               X                                          |      1     |
      Cyst                                 |                                           4                              |      1  4.0|
      Eosinophilic Focus                   |          X  X  X        X     X                       X        X     X   |     14     |
      Hematopoietic Cell Proliferation     | 3                                                                        |      1  3.0|
      Mixed Cell Focus                     |       X                 X     X                                          |      3     |
      Necrosis                             |                      1                          2                        |      5  2.4|
      Centrilobular, Degeneration          |                                                                          |      1  2.0|
      Midzonal, Vacuolization Cytoplasmic  |                                        2                                 |      1  2.0|
      Periportal, Vacuolization Cytoplasmic|                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |          +           +           +        +        +                     |  13        |
      Fat, Necrosis                        |          3           2           3                 3                     |     11  3.1|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
      Acinus, Atrophy                      |                                                                          |      1  3.0|
      Artery, Inflammation, Chronic        |                                                                          |      1  2.0|
      Duct, Cyst                           |                                                                      1   |      2  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    | 1  1     1  1  1  1  1  2  2  1  1  1        2  1  1  1        2  2  1  1|     36  1.3|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Necrosis                             |                                           2              2              1|      4  1.5|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mineralization                       |             1                                                            |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Hematopoietic Cell Proliferation     |                                                          2               |      1  2.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  20                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 7| 6| 7| 6| 6| 7| 7| 7| 5| 7| 5| 6| 7| 6| 7| 7| 4| 7| 7| 7| 6| 5|            |
                             DAY ON TEST   | 0| 5| 0| 2| 9| 2| 5| 3| 2| 2| 2| 8| 2| 0| 2| 2| 4| 2| 1| 1| 2| 2| 2| 7| 6|            |
                                           | 8| 6| 0| 9| 2| 9| 9| 2| 9| 9| 9| 3| 9| 9| 4| 9| 8| 9| 2| 7| 2| 9| 9| 8| 4|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    250 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Capsule, Hyperplasia                 | 1     1  1  2  1  2  1  2  1  1  1  2     1  1     1  1  2  1  1  1      |     39  1.3|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | M  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  45        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
      Hyperplasia                          |                            2                                             |      2  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | M  M  +  +  M  +  M  M  M  +  M  A  +  +  +  +  +  +  M  +  +  +  +  +  +|  30        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | M  +  M  +  +  +  +  M  +  +  +  +  +  +  I  +  +  M  +  +  +  +  +  +  +|  42        |
      Pars Distalis, Hyperplasia           |                                  2                          2     1  1   |      6  1.7|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Follicle, Cyst                       |             2                                                            |      1  2.0|
      Follicular Cell, Hyperplasia         |       1  3     4  2     2  2  4                                2  1  1   |     22  2.2|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Peritoneum                              |                                                          +               |   2        |
      Inflammation, Chronic Active         |                                                          4               |      1  4.0|
                                            __________________________________________________________________________|____________|
   Tissue NOS                              |                                                                          |   2        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Atrophy                              | 3  3  4  3  3  2  4  3  3  2  4  3  3  3  3  3  3  3  3  2  3  3  3  4  3|     45  3.1|
      Inflammation, Chronic                |                                                                          |      1  2.0|
      Inflammation, Chronic Active         |                                                          1               |      3  2.0|
      Pigmentation                         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  46        |
      Cyst                                 |                            1        2  3     1        4              1   |     11  2.5|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  47        |
      Cyst                                 |                                                       4                  |      5  3.8|
      Hyperplasia, Cystic                  | 3  1  3  3  2  2     2  4  1  4  2  2     1  2     3  4     1  1  4  1  1|     38  2.3|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Lymph Node                              |             +                    +  +     +                       +      |   7        |
      Iliac, Hyperplasia, Lymphoid         |                                     1                             4      |      2  2.5|
      Inguinal, Hyperplasia, Lymphoid      |                                                                          |      1  4.0|
      Mediastinal, Hemorrhage              |             2                                                            |      1  2.0|
      Mediastinal, Pigmentation            |                                  2                                       |      1  2.0|
      Renal, Hemorrhage                    |                                           2                              |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hemorrhage                           |    2                                                                     |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  A  +  M  +  +  +  +  +  +  A  +  +  +  +  +  +  M  +|  43        |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  21                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 7| 6| 7| 6| 6| 7| 7| 7| 5| 7| 5| 6| 7| 6| 7| 7| 4| 7| 7| 7| 6| 5|            |
                             DAY ON TEST   | 0| 5| 0| 2| 9| 2| 5| 3| 2| 2| 2| 8| 2| 0| 2| 2| 4| 2| 1| 1| 2| 2| 2| 7| 6|            |
                                           | 8| 6| 0| 9| 2| 9| 9| 2| 9| 9| 9| 3| 9| 9| 4| 9| 8| 9| 2| 7| 2| 9| 9| 8| 4|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    250 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Angiectasis                          |                                                                          |      1  2.0|
      Hemorrhage                           |       4     3                                               2            |      3  3.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  48        |
      Atrophy                              |                                                             2            |      1  2.0|
      Hematopoietic Cell Proliferation     | 4  4  2     2  2     1  2  2  4  3  2  3     1        4  4     4  2  2   |     32  2.5|
      Hemorrhage                           |                                           3                              |      1  3.0|
      Hyperplasia, Lymphoid                |          3                                         1              1      |      4  2.3|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +  +  M  +|  46        |
      Atrophy                              | 2  2  3                                3                 2               |     13  2.6|
      Ectopic Parathyroid Gland            |                   2                                                      |      2  2.0|
      Hyperplasia, Lymphoid                |                   2                                                      |      1  2.0|
      Necrosis                             |                      2                                                   |      3  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               |                2                                                         |      2  2.0|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mineralization                       | 2     2  2        2  2        2  1  2     2              2        2     2|     18  1.9|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      4  2.3|
      Alveolar Epithelium, Hyperplasia     |                                                 4                        |      1  4.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  A|  47        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         | 2  2  2  2  2  2  2  1  1  1  2              2     1  2     1  2     2   |     35  1.8|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         | 1     1              1  1     2              1                       1   |     12  1.3|
      Respiratory Epithelium, Hyperplasia  |    1                          1  1                                       |     12  1.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  22                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 7| 6| 7| 6| 6| 7| 7| 7| 5| 7| 5| 6| 7| 6| 7| 7| 4| 7| 7| 7| 6| 5|            |
                             DAY ON TEST   | 0| 5| 0| 2| 9| 2| 5| 3| 2| 2| 2| 8| 2| 0| 2| 2| 4| 2| 1| 1| 2| 2| 2| 7| 6|            |
                                           | 8| 6| 0| 9| 2| 9| 9| 2| 9| 9| 9| 3| 9| 9| 4| 9| 8| 9| 2| 7| 2| 9| 9| 8| 4|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|      A     |
    250 PPM                                | 4| 4| 4| 4| 4| 4| 4| 4| 4| 5| 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infarct                              |                                                                          |      1  1.0|
      Infiltration Cellular, Lymphocyte    |                         1                                1     1         |      5  1.6|
      Nephropathy                          |                   1                                                  1   |      7  1.0|
      Glomerulus, Amyloid Deposition       |                                                             4            |      1  4.0|
      Renal Tubule, Dilatation             |                                                                          |      2  2.0|
      Renal Tubule, Pigmentation           |                                  2                             3         |      3  2.7|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  M  +  +  +  +  A|  44        |
      Infiltration Cellular, Lymphocyte    |          2     1        1  1  1              1                    1      |     17  1.1|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  23                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 3| 6| 7| 7| 7| 7| 5| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 5| 7| 7|             
                             DAY ON TEST   | 2| 2| 2| 2| 2| 6| 8| 2| 0| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 9| 2| 9| 2| 2|             
                                           | 9| 9| 9| 9| 9| 6| 6| 9| 0| 9| 9| 6| 9| 9| 9| 9| 9| 9| 5| 9| 0| 9| 5| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | M  A  +  M  M  +  A  +  M  M  +  +  +  +  +  M  +  +  +  +  A  M  +  +  +|             
      Hyperplasia                          |                                           4                              |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Artery, Necrosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  M  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Clear Cell Focus                     |       X                       X                                          |             
      Eosinophilic Focus                   |       X                          X                    X  X           X   |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Necrosis                             |             3  2  2                       4                              |             
      Vacuolization Cytoplasmic, Diffuse   |                                                                          |             
      Centrilobular, Congestion            |                                                                          |             
      Centrilobular, Degeneration          |                2                                                         |             
                                            __________________________________________________________________________|             
   Mesentery                               |                      +     +     +              +  +  +  +               |             
      Fat, Necrosis                        |                      4     4     4              3  3     4               |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Inflammation, Chronic Active         |                               3                          4               |             
      Acinus, Atrophy                      |                               2                          4               |             
      Duct, Cyst                           |                               3                          4               |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1  2  1     1        2     1        1     2  1     2     2     1  1  2  1|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                         2                                                |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrium, Thrombosis                   |                         4                                                |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               |                                                                          |             
      Hemorrhage                           |                         2                                   2            |             
      Capsule, Hyperplasia                 | 2  1  2  3  2     1  1  1  1  2  1  3  2  1  1  1  2  1  1  1  1  1  1  2|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                     1                             2      |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  M  +  M  M  +  M  +  +  M  +  +  +  +  +  +  +  +  M  M|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  24                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 3| 6| 7| 7| 7| 7| 5| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 5| 7| 7|             
                             DAY ON TEST   | 2| 2| 2| 2| 2| 6| 8| 2| 0| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 9| 2| 9| 2| 2|             
                                           | 9| 9| 9| 9| 9| 6| 6| 9| 0| 9| 9| 6| 9| 9| 9| 9| 9| 9| 5| 9| 0| 9| 5| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    | 1                                                                        |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Pars Distalis, Angiectasis           |                               2                                          |             
      Pars Distalis, Hyperplasia           |                                        2                 1              1|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |             1                             1              1               |             
      Follicular Cell, Hyperplasia         | 1  2  1  2  4              2  3     1  2     2  1  2     1     2        1|             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Clitoral Gland                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +  +  +  +|             
      Atrophy                              | 4  4  3  3  3     3  3  4  3  2  2  3  3  3  4  3  3  3     3  3  3  3  3|             
      Inflammation, Chronic                |                               2           1  1  1                        |             
      Pigmentation                         |                                                       2              2   |             
                                            __________________________________________________________________________|             
   Ovary                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    2        3           1           3     4     4              2         |             
                                            __________________________________________________________________________|             
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                          4               |             
      Hyperplasia, Cystic                  | 2  2  3  3  1  3     1        3     2  3  2     1  3  2     2  2  2  1  2|             
      Inflammation, Chronic Active         |                               3                                          |             
      Pigmentation                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Myeloid Cell, Hyperplasia            |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                               +                       +                  |             
      Iliac, Inflammation, Chronic Active  |                               3                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  M  M  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |          2                                2                              |             
      Hematopoietic Cell Proliferation     |                                                          1               |             
      Hemorrhage                           |                         3                                                |             
      Artery, Necrosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     | 3  2  2  3  3  2  3     2  2  2     1  2  2  3  3  3  3  3  3  3  1     3|             
      Hyperplasia, Lymphoid                |                               1                                2         |             
      Pigmentation                         |                                  3                                       |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  I  +  I  +  +  M  +  M  +  +  M  +  +  +  +  +  +  +  +  M  +  +  M  +|             
      Atrophy                              | 2              3                                                         |             
      Necrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  25                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 3| 6| 7| 7| 7| 7| 5| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 5| 7| 7|             
                             DAY ON TEST   | 2| 2| 2| 2| 2| 6| 8| 2| 0| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 9| 2| 9| 2| 2|             
                                           | 9| 9| 9| 9| 9| 6| 6| 9| 0| 9| 9| 6| 9| 9| 9| 9| 9| 9| 5| 9| 0| 9| 5| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                2                                                         |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                       +                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst Epithelial Inclusion            |                                                                          |             
      Mineralization                       | 1     2  2     1  2  1  2              1  2                          1   |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                           1                              |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                                                                      3   |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         | 1  2  2  1  2     2  1     2  2  1  1  1  2  1  2  1  2  2  2  2  1     2|             
      Olfactory Epithelium, Inflammation,  |                                                                          |             
           Chronic Active                  |                                                                          |             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         |             1        1                 1     1        1  2        1  2  1|             
      Respiratory Epithelium, Hyperplasia  |                                                          1           2   |             
      Respiratory Epithelium, Inflammation,|                                                                          |             
           Chronic Active                  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                     +                                    |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Plasma Cell   |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                           1                              |             
      Nephropathy                          |    2  1  2                 1                    1              1         |             
      Renal Tubule, Dilatation             |                                                                          |             
      Renal Tubule, Pigmentation           |    3                                                                     |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  26                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 7| 7| 7| 3| 6| 7| 7| 7| 7| 5| 7| 7| 7| 7| 7| 7| 6| 7| 6| 7| 5| 7| 7|             
                             DAY ON TEST   | 2| 2| 2| 2| 2| 6| 8| 2| 0| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 9| 2| 9| 2| 2|             
                                           | 9| 9| 9| 9| 9| 6| 6| 9| 0| 9| 9| 6| 9| 9| 9| 9| 9| 9| 5| 9| 0| 9| 5| 9| 9|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3|             
    500 PPM                                | 6| 6| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9|             
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Renal Tubule, Regeneration           |                1                                                         |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    1  1     1                 1           1  1  1     1  1        1     1|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  27                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 7| 6| 5| 0| 7| 7| 6| 4| 7| 7| 6| 7| 6| 0| 1| 7| 7| 7| 7| 7| 7| 0| 4| 5|            |
                             DAY ON TEST   | 9| 2| 9| 1| 1| 2| 2| 2| 7| 2| 2| 7| 2| 8| 1| 8| 2| 2| 0| 2| 2| 2| 1| 3| 7|            |
                                           | 9| 9| 0| 0| 5| 9| 9| 6| 9| 9| 9| 7| 9| 0| 4| 8| 9| 9| 3| 9| 9| 9| 2| 0| 1|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | +  +  M  A  +  +  +  +  +  +  +  A  +  A  M  +  +  +  A  +  +  +  +  +  +|  34        |
      Hyperplasia                          |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  A  +  +  +  A  +  +|  45        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Artery, Necrosis                     |                      3                                                   |      1  3.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|  45        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  A  +  +  +  +  +  +  +  A  +  A  +  +  +  +  A  +  +  +  A  +  +|  42        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  A  +  +  +  +  +  +  +  +  A  +  +  A  +  +  +  A  +  +  +  A  +  +|  43        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  A  +  +  +  +  +  +  +  +  A  +  A  +  A  +  +  A  +  +  +  A  +  +|  41        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Clear Cell Focus                     |                                                                          |      2     |
      Eosinophilic Focus                   |    X     X        X     X                                                |      9     |
      Hematopoietic Cell Proliferation     |                   1                                                      |      1  1.0|
      Necrosis                             |                         1     4                                4         |      7  2.9|
      Vacuolization Cytoplasmic, Diffuse   |                                                                      1   |      1  1.0|
      Centrilobular, Congestion            |                                              1                           |      1  1.0|
      Centrilobular, Degeneration          |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                +  +              +     +              +     +            |  13        |
      Fat, Necrosis                        |                3                                      3     4            |      9  3.6|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  48        |
      Inflammation, Chronic Active         |                                                                          |      2  3.5|
      Acinus, Atrophy                      |                                                                          |      2  3.0|
      Duct, Cyst                           |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    | 2     1        1     1     1        1  1        1  1  1     1  1     1  1|     29  1.2|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Necrosis                             |                                                                      1  1|      3  1.3|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M     +|  47        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrium, Thrombosis                   |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cytoplasmic Alteration               |                                                    3     1               |      2  2.0|
      Hemorrhage                           |                                                                          |      2  2.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  28                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 7| 6| 5| 0| 7| 7| 6| 4| 7| 7| 6| 7| 6| 0| 1| 7| 7| 7| 7| 7| 7| 0| 4| 5|            |
                             DAY ON TEST   | 9| 2| 9| 1| 1| 2| 2| 2| 7| 2| 2| 7| 2| 8| 1| 8| 2| 2| 0| 2| 2| 2| 1| 3| 7|            |
                                           | 9| 9| 0| 0| 5| 9| 9| 6| 9| 9| 9| 7| 9| 0| 4| 8| 9| 9| 3| 9| 9| 9| 2| 0| 1|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
      Capsule, Hyperplasia                 |    1     1     1  1  1     1                    2  2  1  1  1  1        1|     37  1.4|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  49        |
      Hyperplasia                          |       1                                                                  |      3  1.3|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  +  +  +  +  M  +  +  +  M  M  M  +  M  +  +  +  M  +  +  +  +  +  +|  36        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +  +|  46        |
      Hemorrhage                           |                   2                                                      |      1  2.0|
      Pars Distalis, Angiectasis           |                                                                          |      1  2.0|
      Pars Distalis, Hyperplasia           |                               1     1           3  1           2         |      8  1.5|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      3  1.0|
      Follicular Cell, Hyperplasia         |                2  1        1        2  1        1  1  1                  |     23  1.6|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Clitoral Gland                          | +  +  +  +  M  +  +  M  +  +  M  +  +  +  M  +  +  +  +  +  +  +  +  +  +|  45        |
      Atrophy                              | 3  3  4  2     3  3     4  3     4  3  4     3  2  4  4  3  3  3     4  4|     43  3.2|
      Inflammation, Chronic                |                                                                          |      4  1.3|
      Pigmentation                         |                   2                                                      |      3  2.0|
                                            __________________________________________________________________________|____________|
   Ovary                                   | +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 |    1                 1                                   2  2            |     11  2.3|
                                            __________________________________________________________________________|____________|
   Uterus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                    4                     |      2  4.0|
      Hyperplasia, Cystic                  | 1  3  2  1     2  1  1  2  1  2  1  1  2        3  2     1  3  2     3  4|     39  2.0|
      Inflammation, Chronic Active         |                                                                          |      1  3.0|
      Pigmentation                         |                               2                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Myeloid Cell, Hyperplasia            |          2                       3                                       |      2  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |    +     +        +                                +     +               |   7        |
      Iliac, Inflammation, Chronic Active  |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Hemorrhage                           |                                                                2         |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  A  +  +  M  +  +  +  A  +  +  +  M  +  +|  45        |
      Angiectasis                          |                                                                          |      2  2.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  29                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 7| 6| 5| 0| 7| 7| 6| 4| 7| 7| 6| 7| 6| 0| 1| 7| 7| 7| 7| 7| 7| 0| 4| 5|            |
                             DAY ON TEST   | 9| 2| 9| 1| 1| 2| 2| 2| 7| 2| 2| 7| 2| 8| 1| 8| 2| 2| 0| 2| 2| 2| 1| 3| 7|            |
                                           | 9| 9| 0| 0| 5| 9| 9| 6| 9| 9| 9| 7| 9| 0| 4| 8| 9| 9| 3| 9| 9| 9| 2| 0| 1|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Hematopoietic Cell Proliferation     |                                                                          |      1  1.0|
      Hemorrhage                           |                      3                                                   |      2  3.0|
      Artery, Necrosis                     |                      2                                                   |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|  49        |
      Hematopoietic Cell Proliferation     | 2     3        3  2  3     1  4  4  2  3        1  2  2  2  2  3        2|     39  2.4|
      Hyperplasia, Lymphoid                |                                                                          |      2  1.5|
      Pigmentation                         |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  A  +  +  +  +  M  +  +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  +|  39        |
      Atrophy                              | 2  2     2              4              3                       2  4  2   |     10  2.6|
      Necrosis                             |             2                             1                          2   |      3  1.7|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst Epithelial Inclusion            |                                                                2         |      1  2.0|
      Mineralization                       |                   1     2  2     2  1              2  1              1  2|     19  1.5|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                           2  2                    2      |      3  2.0|
      Hemorrhage                           |                                              2                           |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                      2                                                   |      2  2.5|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |    2  1        1  1        1  1  1  1  2        1  1  1  2     2         |     36  1.5|
      Olfactory Epithelium, Inflammation,  |                                                                          |            |
           Chronic Active                  |                                                 1                        |      1  1.0|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         |                      1              1  2        1                        |     13  1.2|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  30                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 2| 7| 6| 5| 0| 7| 7| 6| 4| 7| 7| 6| 7| 6| 0| 1| 7| 7| 7| 7| 7| 7| 0| 4| 5|            |
                             DAY ON TEST   | 9| 2| 9| 1| 1| 2| 2| 2| 7| 2| 2| 7| 2| 8| 1| 8| 2| 2| 0| 2| 2| 2| 1| 3| 7|            |
                                           | 9| 9| 0| 0| 5| 9| 9| 6| 9| 9| 9| 7| 9| 0| 4| 8| 9| 9| 3| 9| 9| 9| 2| 0| 1|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE FEMALE                      | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4|      A     |
    500 PPM                                | 9| 9| 9| 9| 9| 9| 9| 9| 9| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1|      L     |
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Respiratory Epithelium, Hyperplasia  |                            1        1                                    |      4  1.3|
      Respiratory Epithelium, Inflammation,|                                                                          |            |
           Chronic Active                  |                                                    1                     |      1  1.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  49        |
      Infiltration Cellular, Plasma Cell   |                                                 3                        |      1  3.0|
      Infiltration Cellular, Lymphocyte    |                                                       1                  |      2  1.0|
      Nephropathy                          |                   1  3                                                   |      8  1.5|
      Renal Tubule, Dilatation             |             2                                                        2   |      2  2.0|
      Renal Tubule, Pigmentation           |                                        3                                 |      2  3.0|
      Renal Tubule, Regeneration           |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  A  +  +  +  +  +  +  +  +  A  +  A  +  +  +  +  A  +  +  +  +  +  +|  43        |
      Infiltration Cellular, Lymphocyte    | 1  1     1     1  1  1     1        1           1  2                    1|     22  1.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  31                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 1| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 6| 7| 5|             
                             DAY ON TEST   | 3| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 2| 2| 2| 3| 2| 2| 2| 7| 2| 7| 0| 7|             
                                           | 9| 3| 3| 3| 1| 3| 3| 3| 3| 3| 2| 8| 2| 2| 2| 2| 3| 2| 2| 2| 0| 2| 2| 6| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  A  +  A  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                         1|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                   2      |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  A  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  A  +  M  A  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  +  +  A  +  A  A  +|             
      Peyer's Patch, Hyperplasia, Lymphoid |                               2                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  +  +  A  +  +  A  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                      1                                                   |             
      Basophilic Focus                     |                                                                          |             
      Clear Cell Focus                     |                                                                          |             
      Eosinophilic Focus                   |    X  X  X        X     X  X  X     X        X  X                    X   |             
      Hemorrhage                           |                                                                          |             
      Infiltration Cellular, Mixed Cell    |                                                                          |             
      Mixed Cell Focus                     |                                              X        X                  |             
      Necrosis                             |                                                                         1|             
      Vacuolization Cytoplasmic, Diffuse   |    2     2                                                               |             
      Centrilobular, Congestion            |                                                                      3   |             
      Centrilobular, Vacuolization         |                                                                          |             
          Cytoplasmic                      |                                  2                                       |             
      Periportal, Vacuolization Cytoplasmic|                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                          |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Oral Mucosa                             |                                                                          |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |                         1                                         3     2|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |       1  1  1  2     1  1     1     1     1        1  1  1              2|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                      3   |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                                                 2                       2|             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
                                            __________________________________________________________________________|             
   Tooth                                   | +  +  +  +  +  +  +  +  +  +        +  +  +     +  +     +  +  +  +  +  +|             
      Developmental Malformation           | 3  4  4  2  3  3  3  4  4  4        4  3  4     3  2     2  3  4  3  3  1|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Aorta, Thrombosis                    |                                                                   4      |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  32                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 1| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 6| 7| 5|             
                             DAY ON TEST   | 3| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 2| 2| 2| 3| 2| 2| 2| 7| 2| 7| 0| 7|             
                                           | 9| 3| 3| 3| 1| 3| 3| 3| 3| 3| 2| 8| 2| 2| 2| 2| 3| 2| 2| 2| 0| 2| 2| 6| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Artery, Inflammation, Chronic Active |                3                                                         |             
      Myocardium, Hypertrophy              |                                                                         2|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               |    1        2  1                          1        2  1                  |             
      Hyperplasia                          |                                     1                                    |             
      Vacuolization Cytoplasmic            |                                              1                           |             
      Capsule, Hyperplasia                 |    1  1  2     1  3  1  4  2  2     2  2  1  2     2  1     3  2  1  1  1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  M  +  +  +  +  +  M  +  M  +  +  M  M  M  +  +  +  +  +  M  +  +  +|             
      Cyst                                 |                                  2                                       |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  I  +|             
      Cyst                                 |                                                       2                  |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Follicle, Cyst                       |                                                                          |             
      Follicular Cell, Hyperplasia         |       1                 1     1                       1  1               |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Inflammation, Granulomatous          |                                                                      2   |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  3  3  3  3  3  3  3  2  4  2  2  2  3  3  4  4     4  4  4     3  4  2|             
      Cyst                                 |    3  3  3     3           4        3  4     4  3        3  2            |             
      Inflammation, Chronic                |       2                 2     3     2                 2  2     1         |             
      Inflammation, Chronic Active         |             2                                3                           |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                    1                     |             
      Hyperplasia                          |                                                                          |             
      Inflammation, Chronic                |             1                          1                                 |             
      Inflammation, Chronic Active         |                                                                   2      |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Mineralization                       |                                                                          |             
      Interstitial Cell, Hyperplasia       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  33                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 1| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 6| 7| 5|             
                             DAY ON TEST   | 3| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 2| 2| 2| 3| 2| 2| 2| 7| 2| 7| 0| 7|             
                                           | 9| 3| 3| 3| 1| 3| 3| 3| 3| 3| 2| 8| 2| 2| 2| 2| 3| 2| 2| 2| 0| 2| 2| 6| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Myeloid Cell, Hyperplasia            |                                              2                           |             
                                            __________________________________________________________________________|             
   Lymph Node                              | +                                                                        |             
      Iliac, Hyperplasia, Lymphoid         |                                                                          |             
      Mediastinal, Congestion              | 4                                                                        |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Hyperplasia, Lymphoid                |                   2        2           2                                 |             
      Hyperplasia, Plasma Cell             |                                                                      2   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | M  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  A  +  +  M  +|             
      Hematopoietic Cell Proliferation     |                                           2                              |             
      Hemorrhage                           |    1     2     3  2                       2        1              2      |             
      Hyperplasia, Histiocytic             |                            1                                             |             
      Hyperplasia, Lymphoid                |                                              2                           |             
      Hyperplasia, Plasma Cell             |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                                       2  2        1  4  1|             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +|             
      Atrophy                              | 2  2  1     2     1  2  2  2     3           1  3     2           3  3  3|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  M  +  M  M  M  M  M  M  M  M  M  M  M  M  M  +  M  M  M  +  M  M  M|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                          |             
      Ulcer                                |                                                                         1|             
      Subcutaneous Tissue, Edema           |                                                                      3   |             
      Subcutaneous Tissue, Inflammation,   |                                                                          |             
           Chronic Active                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                   1      |             
      Mineralization                       | 1  2  2  3     1  3  2  2  2  3     2  2  2  2  1  2  2     2  2     1  2|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Alveolar Epithelium, Hyperplasia     |    1                    2                                                |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  34                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 7| 7| 6| 7| 7| 7| 7| 7| 7| 1| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 6| 7| 5|             
                             DAY ON TEST   | 3| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 1| 2| 2| 2| 2| 3| 2| 2| 2| 7| 2| 7| 0| 7|             
                                           | 9| 3| 3| 3| 1| 3| 3| 3| 3| 3| 2| 8| 2| 2| 2| 2| 3| 2| 2| 2| 0| 2| 2| 6| 4|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Foreign Body                         |                                                                          |             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         |                            1        1     2     2     3  2              2|             
      Olfactory Epithelium, Glands,        |                                                                          |             
          Hyperplasia                      |                                                                      3   |             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         |       1        1     1  1  1        2     1     2           1        1  1|             
      Respiratory Epithelium, Hyperplasia  |       1  2                    1     2           3  2        3     2  3  2|             
      Respiratory Epithelium, Inflammation,|                                                                          |             
           Chronic Active                  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cataract                             |                                                                          |             
      Cornea, Inflammation, Chronic        |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                      +                          +                        |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                               2                    2                     |             
      Hydronephrosis                       |                                                                          |             
      Infarct                              |                            1                                             |             
      Infiltration Cellular, Lymphocyte    |                1                                                         |             
      Inflammation, Chronic Active         |                                                 4                 3      |             
      Mineralization                       |                                                             1            |             
      Nephropathy                          |    1  1  1  1  1  1     1  1        1  1  2  1     1  2  3              1|             
      Artery, Inflammation, Chronic        |                                                                          |             
      Artery, Inflammation, Chronic Active |                                                                          |             
      Renal Tubule, Hyperplasia            |    1                 3                                                   |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                1     1        1           1                    1         |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  35                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 7| 7| 6| 7| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7|            |
                             DAY ON TEST   | 2| 6| 2| 2| 5| 2| 9| 2| 1| 2| 2| 2| 2| 2| 4| 2| 2| 3| 2| 2| 2| 2| 2| 2| 2|            |
                                           | 2| 3| 2| 2| 3| 3| 8| 3| 4| 3| 3| 0| 3| 3| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      A     |
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | +  +  +  +  A  +  +  +  A  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|  43        |
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  A  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  43        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  A  +  A  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|  40        |
      Peyer's Patch, Hyperplasia, Lymphoid |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  A  +  A  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  42        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                                                          |      1  1.0|
      Basophilic Focus                     |    X                                   X     X                           |      3     |
      Clear Cell Focus                     |                                                                         X|      1     |
      Eosinophilic Focus                   |    X  X        X           X           X           X                 X  X|     19     |
      Hemorrhage                           |          2                                                               |      1  2.0|
      Infiltration Cellular, Mixed Cell    |                                           1                              |      1  1.0|
      Mixed Cell Focus                     |                                                       X           X      |      4     |
      Necrosis                             |                   1                    4                                 |      3  2.0|
      Vacuolization Cytoplasmic, Diffuse   |                                                                          |      2  2.0|
      Centrilobular, Congestion            |                                                                          |      1  3.0|
      Centrilobular, Vacuolization         |                                                                          |            |
          Cytoplasmic                      |                                                                          |      1  2.0|
      Periportal, Vacuolization Cytoplasmic|                                  2                                       |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                 +           +            |   2        |
      Fat, Necrosis                        |                                                 4           3            |      2  3.5|
                                            __________________________________________________________________________|____________|
   Oral Mucosa                             |    +                                                                     |   1        |
      Ulcer                                |    4                                                                     |      1  4.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Acinus, Atrophy                      |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Infiltration Cellular, Lymphocyte    | 2  1  1  1     1  1           1  1  2  1  1     1     1  1  2  1  1  1   |     31  1.2|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Inflammation, Chronic Active         |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Necrosis                             |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                                        +                                 |   1        |
                                            __________________________________________________________________________|____________|
   Tooth                                   | +  +  +  +  +  +  +  +     +     +  +  +  +  +  +     +     +  +  +  +  +|  42        |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  36                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 7| 7| 6| 7| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7|            |
                             DAY ON TEST   | 2| 6| 2| 2| 5| 2| 9| 2| 1| 2| 2| 2| 2| 2| 4| 2| 2| 3| 2| 2| 2| 2| 2| 2| 2|            |
                                           | 2| 3| 2| 2| 3| 3| 8| 3| 4| 3| 3| 0| 3| 3| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      A     |
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
      Developmental Malformation           | 4  3  2  4  4  2  3  4     3     2  4  2  4  2  4     4     2  3  2  4  2|     42  3.1|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Aorta, Thrombosis                    |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Artery, Inflammation, Chronic Active |                   2                                                      |      2  2.5|
      Myocardium, Hypertrophy              |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cytoplasmic Alteration               | 2        1     1  2  1              1           3        1     2  1  1  1|     18  1.4|
      Hyperplasia                          |                1                                                         |      2  1.0|
      Vacuolization Cytoplasmic            |    1                                                                     |      2  1.0|
      Capsule, Hyperplasia                 | 1  1  2  1  1  2  4           1  1  2  2  1  3  1  1  3  2  1  2  1  1  1|     42  1.7|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | M  +  +  M  +  +  M  +  A  +  M  +  +  M  M  M  +  +  +  +  +  M  M  +  M|  31        |
      Cyst                                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  M  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  46        |
      Cyst                                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Follicle, Cyst                       |                                        1                                 |      1  1.0|
      Follicular Cell, Hyperplasia         |                               2                             1     1      |      8  1.1|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    | 1                                                                        |      1  1.0|
      Inflammation, Granulomatous          |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              | 3  4  3  4  4  3  4  3  3  4  2  2  3  3  3  2  2  3  4  2  2  2  2  4  3|     48  3.0|
      Cyst                                 |       2     2  3  4  3  4  4  4  2     3  4  4  4     4  2     4  2     3|     29  3.2|
      Inflammation, Chronic                |       2        1     1           1     2  1  1        1  2     2        2|     18  1.7|
      Inflammation, Chronic Active         |                                     4           2                        |      4  2.8|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      1  1.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  37                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 7| 7| 6| 7| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7|            |
                             DAY ON TEST   | 2| 6| 2| 2| 5| 2| 9| 2| 1| 2| 2| 2| 2| 2| 4| 2| 2| 3| 2| 2| 2| 2| 2| 2| 2|            |
                                           | 2| 3| 2| 2| 3| 3| 8| 3| 4| 3| 3| 0| 3| 3| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      A     |
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Hyperplasia                          |                                                 2                        |      1  2.0|
      Inflammation, Chronic                |       1                 1     1  1                          1            |      7  1.0|
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              | 2                             3                                          |      2  2.5|
      Mineralization                       |       1                                                                  |      1  1.0|
      Interstitial Cell, Hyperplasia       |                               3                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |          3           1                                                   |      2  2.0|
      Myeloid Cell, Hyperplasia            |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                           +                              |   2        |
      Iliac, Hyperplasia, Lymphoid         |                                           2                              |      1  2.0|
      Mediastinal, Congestion              |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Hyperplasia, Lymphoid                |                                                                          |      3  2.0|
      Hyperplasia, Plasma Cell             |                                        2                                 |      2  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|  43        |
      Hematopoietic Cell Proliferation     | 2                                                                        |      2  2.0|
      Hemorrhage                           |             4  1                                   3        2     1     2|     13  2.0|
      Hyperplasia, Histiocytic             |                   3                                                      |      2  2.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
      Hyperplasia, Plasma Cell             |       3                                                                  |      1  3.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hematopoietic Cell Proliferation     |    3        4     3              1           1     3        3     1      |     13  2.2|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  M  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  46        |
      Atrophy                              |    4     2     2                    2  2  3  2     3     1  2        3   |     26  2.2|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  M  M  +  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|   5        |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Inflammation, Chronic Active         |                                                          2               |      1  2.0|
      Ulcer                                |                                                                          |      1  1.0|
      Subcutaneous Tissue, Edema           |                                                                          |      1  3.0|
      Subcutaneous Tissue, Inflammation,   |                                                                          |            |
           Chronic Active                  |             4                                                            |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  38                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 7| 7| 6| 7| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7|            |
                             DAY ON TEST   | 2| 6| 2| 2| 5| 2| 9| 2| 1| 2| 2| 2| 2| 2| 4| 2| 2| 3| 2| 2| 2| 2| 2| 2| 2|            |
                                           | 2| 3| 2| 2| 3| 3| 8| 3| 4| 3| 3| 0| 3| 3| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      A     |
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                                          |      1  1.0|
      Mineralization                       | 2  1  1  2  3  1  2        2  1  1     3  2  2  1  2  2  1     2  2     2|     41  1.9|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Congestion                           |                   2                                                      |      1  2.0|
      Alveolar Epithelium, Hyperplasia     |       1                                                        4         |      4  2.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |          2                                                               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |             X                                                            |      1     |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |             2  1  2           1  2           2        2     2            |     15  1.8|
      Olfactory Epithelium, Glands,        |                                                                          |            |
          Hyperplasia                      |                                                                          |      1  3.0|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         | 1           2  1        2     1     1  1  1                       1      |     20  1.2|
      Respiratory Epithelium, Hyperplasia  | 2        1     2     1              1     2     1     2     2  2         |     20  1.9|
      Respiratory Epithelium, Inflammation,|                                                                          |            |
           Chronic Active                  |             1                                         2                  |      2  1.5|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                        +                                 |   1        |
      Cataract                             |                                        4                                 |      1  4.0|
      Cornea, Inflammation, Chronic        |                                        4                                 |      1  4.0|
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                         +     +        +  M                              |   5        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 |                                           2                          2   |      4  2.0|
      Hydronephrosis                       |                   1                                                      |      1  1.0|
      Infarct                              |                            1                                             |      2  1.0|
      Infiltration Cellular, Lymphocyte    |                               2                             3            |      3  2.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  39                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 7| 7| 6| 7| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 6| 7| 7| 7| 7| 7| 7| 7|            |
                             DAY ON TEST   | 2| 6| 2| 2| 5| 2| 9| 2| 1| 2| 2| 2| 2| 2| 4| 2| 2| 3| 2| 2| 2| 2| 2| 2| 2|            |
                                           | 2| 3| 2| 2| 3| 3| 8| 3| 4| 3| 3| 0| 3| 3| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      A     |
    0 PPM                                  | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 URINARY SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic Active         |                                                                          |      2  3.5|
      Mineralization                       |                                           1                              |      2  1.0|
      Nephropathy                          | 2  2  1  1     1  1  1     1  2  2  1        2  1  3     1     1  2     1|     34  1.4|
      Artery, Inflammation, Chronic        |                                                             2            |      1  2.0|
      Artery, Inflammation, Chronic Active |                                        3                                 |      1  3.0|
      Renal Tubule, Hyperplasia            |                                                          2               |      3  2.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Infiltration Cellular, Lymphocyte    |                                                 1     1        1         |      8  1.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  40                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 6| 7| 6| 7| 6| 7| 5| 7| 7| 7| 6| 6| 5| 2| 7| 7| 7| 6| 5|             
                             DAY ON TEST   | 2| 0| 2| 2| 2| 2| 7| 2| 3| 2| 9| 0| 2| 2| 2| 2| 8| 7| 3| 3| 2| 2| 2| 5| 6|             
                                           | 2| 8| 2| 2| 2| 2| 6| 2| 8| 2| 2| 2| 2| 2| 2| 2| 0| 7| 2| 7| 2| 2| 2| 0| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    250 PPM                                | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | +  +  +  +  +  M  A  +  A  +  A  M  +  +  +  M  +  A  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +  +  +|             
      Peyer's Patch, Hyperplasia, Lymphoid |                                           4                              |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  A  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                      2   |             
      Basophilic Focus                     |                                                 X                        |             
      Clear Cell Focus                     |                                                             X            |             
      Eosinophilic Focus                   |          X        X  X           X  X     X     X  X        X  X        X|             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Infiltration Cellular, Mixed Cell    |                                                       2                  |             
      Mixed Cell Focus                     |                                           X                              |             
      Necrosis                             |                                                    2  2                  |             
      Vacuolization Cytoplasmic, Diffuse   |                                                                          |             
      Centrilobular, Vacuolization         |                                                                          |             
          Cytoplasmic                      |                                                                          |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                     +           +        +              +|             
      Fat, Necrosis                        |                                     3                                    |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |                         3        2                                       |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1  1  1     1     1  1     1  1  2  1  1  1  1  1     1     1     1     1|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                          |             
      Epithelium, Hyperplasia              |                                                 3                        |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |                   2                                                      |             
                                            __________________________________________________________________________|             
   Tooth                                   |       +                             +                       +            |             
      Developmental Malformation           |       2                             2                       2            |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization                       |                                                                      2   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               |          1                       3  1                       1            |             
      Hyperplasia                          |                1                                                         |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  41                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 6| 7| 6| 7| 6| 7| 5| 7| 7| 7| 6| 6| 5| 2| 7| 7| 7| 6| 5|             
                             DAY ON TEST   | 2| 0| 2| 2| 2| 2| 7| 2| 3| 2| 9| 0| 2| 2| 2| 2| 8| 7| 3| 3| 2| 2| 2| 5| 6|             
                                           | 2| 8| 2| 2| 2| 2| 6| 2| 8| 2| 2| 2| 2| 2| 2| 2| 0| 7| 2| 7| 2| 2| 2| 0| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    250 PPM                                | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Capsule, Hyperplasia                 | 1  1  1  2     1     1        1  1  1     1  1     1  1     1  1         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                               2                    2                    3|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  M  +  +  M  +  +  M  M  +  M  +  +  +  M  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  M  +|             
      Cyst                                 |                                                                          |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Follicular Cell, Hyperplasia         | 2           1              1  1              1                 2  1      |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       |                                                                         +|             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Infiltration Cellular, Lymphocyte    | 1                             1                                          |             
      Inflammation, Granulomatous          |                3                                                         |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  3  4  3  3  4  2     3  4  4  3     3  4  3  3     3  4  3  3  3  4  4|             
      Cyst                                 | 3     2     2  3              4  4     4  4     4           3           2|             
      Inflammation, Chronic                | 2  2              2        2  1           1                 2            |             
      Inflammation, Chronic Active         |                         4        4                 4                    1|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                                                   1      |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                3                                                         |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erythroid Cell, Hyperplasia          |    2                                                                     |             
      Myeloid Cell, Hyperplasia            |                3                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node                              |       +                                         +                       +|             
      Pancreatic, Hyperplasia, Lymphoid    |       4                                                                  |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  M  +|             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                 2                 1      |             
      Hematopoietic Cell Proliferation     |                2                                                        2|             
      Hemorrhage                           |                2  3  2  2                                   1        3  1|             
      Hyperplasia, Lymphoid                |    2  2                                   3           1        1         |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  42                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 6| 7| 6| 7| 6| 7| 5| 7| 7| 7| 6| 6| 5| 2| 7| 7| 7| 6| 5|             
                             DAY ON TEST   | 2| 0| 2| 2| 2| 2| 7| 2| 3| 2| 9| 0| 2| 2| 2| 2| 8| 7| 3| 3| 2| 2| 2| 5| 6|             
                                           | 2| 8| 2| 2| 2| 2| 6| 2| 8| 2| 2| 2| 2| 2| 2| 2| 0| 7| 2| 7| 2| 2| 2| 0| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    250 PPM                                | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hyperplasia, Plasma Cell             |                                                                1         |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                    2                     |             
      Hematopoietic Cell Proliferation     | 1  3  2     3  3  2     4  3  4     1  2        4        4        2  4  4|             
      Hyperplasia, Lymphoid                |                                           1                              |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  I  +|             
      Atrophy                              |       2        2  2     3  3  3  3     1        3  3  4  2     2        3|             
      Cyst                                 |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Subcutaneous Tissue, Edema           |                                                                         3|             
      Subcutaneous Tissue, Inflammation,   |                                                                          |             
           Acute                           |                                                          2               |             
      Subcutaneous Tissue, Inflammation,   |                                                                          |             
           Chronic Active                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |          +                       +                                      +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                          2               |             
      Mineralization                       | 3        1  2  2  2  1  2              2     3  2     2  2     1  1      |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                  +                                       |             
      Sciatic, Degeneration                |                                  2                                       |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                  +                                       |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                          2               |             
      Infiltration Cellular, Lymphocyte    |                                                                1         |             
      Alveolar Epithelium, Hyperplasia     |          1                          1        1              1     2     1|             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                                                                          |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         | 2     1  1  2     2        2     2  1  3  1  2     2           2  2      |             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         | 2        1        1                       1           1                  |             
      Respiratory Epithelium, Hyperplasia  |       1  1           1           1        1  1        1        2     1   |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  43                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 6| 7| 7| 7| 7| 6| 7| 6| 7| 6| 7| 5| 7| 7| 7| 6| 6| 5| 2| 7| 7| 7| 6| 5|             
                             DAY ON TEST   | 2| 0| 2| 2| 2| 2| 7| 2| 3| 2| 9| 0| 2| 2| 2| 2| 8| 7| 3| 3| 2| 2| 2| 5| 6|             
                                           | 2| 8| 2| 2| 2| 2| 6| 2| 8| 2| 2| 2| 2| 2| 2| 2| 0| 7| 2| 7| 2| 2| 2| 0| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    250 PPM                                | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Respiratory Epithelium, Inflammation,|                                                                          |             
           Chronic Active                  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Fibrosis                             |                                                                          |             
      Infarct                              |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                              2                           |             
      Mineralization                       |                                  1                                       |             
      Nephropathy                          | 1  2        1  3  1  1  1  2           1  1  1        1     1  1  2  1   |             
      Renal Tubule, Accumulation, Hyaline  |                                                                          |             
          Droplet                          |                         2                                                |             
      Renal Tubule, Dilatation             |                                                                          |             
      Renal Tubule, Pigmentation           |          3                    4                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |             1     1        1                                             |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  44                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 0| 6| 6| 5| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 7|            |
                             DAY ON TEST   | 2| 8| 0| 9| 7| 9| 2| 2| 2| 1| 2| 2| 4| 4| 2| 2| 2| 2| 4| 2| 2| 9| 2| 2| 2|            |
                                           | 2| 7| 8| 6| 4| 5| 2| 2| 2| 5| 2| 3| 5| 9| 2| 2| 2| 2| 6| 3| 3| 1| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|      A     |
    250 PPM                                | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | +  A  +  A  +  A  M  +  +  M  +  M  A  A  +  +  M  +  M  +  +  +  +  +  +|  33        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  M  +  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  A  +  +  +  +  +  +  +  +  A  A  +  +  +  +  A  +  +  +  +  +  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  A  A  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  +  +  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +|  46        |
      Peyer's Patch, Hyperplasia, Lymphoid |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  A  +  A  +  +  +  A  +  +  A  A  +  +  +  +  A  +  +  +  +  +  +|  41        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                                                          |      1  2.0|
      Basophilic Focus                     |                                                                          |      1     |
      Clear Cell Focus                     |    X                                                           X         |      3     |
      Eosinophilic Focus                   |    X        X  X                          X  X     X     X  X  X  X  X   |     22     |
      Hematopoietic Cell Proliferation     |                      2                                                   |      1  2.0|
      Infiltration Cellular, Mixed Cell    |                                                                          |      1  2.0|
      Mixed Cell Focus                     |    X                                                                     |      2     |
      Necrosis                             |                               4     2                 4                  |      5  2.8|
      Vacuolization Cytoplasmic, Diffuse   |    2                                                                     |      1  2.0|
      Centrilobular, Vacuolization         |                                                                          |            |
          Cytoplasmic                      |                                     2                          2         |      2  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +                       +                                +               |   7        |
      Fat, Necrosis                        | 4                                                        2               |      3  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Acinus, Atrophy                      |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    | 1        1        2  1  1     1  1     1  1     1           2  1  1  1  1|     33  1.1|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                       1                  |      1  1.0|
      Epithelium, Hyperplasia              |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Necrosis                             |                                        2                                 |      2  2.0|
                                            __________________________________________________________________________|____________|
   Tooth                                   |             +        +  +           +                    +        +     +|  10        |
      Developmental Malformation           |             3        2  1           4                    4        3     3|     10  2.6|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mineralization                       |                3                                      2                  |      3  2.3|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  45                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 0| 6| 6| 5| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 7|            |
                             DAY ON TEST   | 2| 8| 0| 9| 7| 9| 2| 2| 2| 1| 2| 2| 4| 4| 2| 2| 2| 2| 4| 2| 2| 9| 2| 2| 2|            |
                                           | 2| 7| 8| 6| 4| 5| 2| 2| 2| 5| 2| 3| 5| 9| 2| 2| 2| 2| 6| 3| 3| 1| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|      A     |
    250 PPM                                | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cytoplasmic Alteration               |    1              1     1     3  1                 1           2     2  1|     13  1.5|
      Hyperplasia                          |                                                                          |      1  1.0|
      Capsule, Hyperplasia                 | 4  1        1           1     1  2     1  1     2        1     1  1  2  1|     29  1.2|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                2                                         2               |      5  2.2|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  M  +  +  +  +  M  +  M  +  +  +  +  +  M  M  M  +  M  M  +  +  +  +|  35        |
      Cyst                                 |                                           2                              |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M|  47        |
      Cyst                                 |                                           1                              |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |                   1                                                      |      1  1.0|
      Follicular Cell, Hyperplasia         | 1                 2                          1  1           2        1  2|     14  1.4|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                            1                                             |      1  1.0|
      Infiltration Cellular, Lymphocyte    |                                           1     1                        |      4  1.0|
      Inflammation, Granulomatous          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              | 3  2     3  3  4  3  4  3  3  3  3  3  4  4  3  3  3  2  4     2  3  2  3|     45  3.2|
      Cyst                                 | 4        4           4  4  3  4  4  3     4     3  3     3     2        2|     25  3.3|
      Inflammation, Chronic                |          2     2     1  1  1  1           2     1     2        3        2|     18  1.7|
      Inflammation, Chronic Active         |                                              2                    4      |      6  3.2|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Chronic                |                                           1                       1      |      3  1.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  46                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 0| 6| 6| 5| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 7|            |
                             DAY ON TEST   | 2| 8| 0| 9| 7| 9| 2| 2| 2| 1| 2| 2| 4| 4| 2| 2| 2| 2| 4| 2| 2| 9| 2| 2| 2|            |
                                           | 2| 7| 8| 6| 4| 5| 2| 2| 2| 5| 2| 3| 5| 9| 2| 2| 2| 2| 6| 3| 3| 1| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|      A     |
    250 PPM                                | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
      Erythroid Cell, Hyperplasia          |                                                                          |      1  2.0|
      Myeloid Cell, Hyperplasia            |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                +                                                         |   4        |
      Pancreatic, Hyperplasia, Lymphoid    |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +|  47        |
      Angiectasis                          |                                                                          |      2  1.5|
      Hematopoietic Cell Proliferation     |                      2                                                   |      3  2.0|
      Hemorrhage                           |          1           2                          1                        |     10  1.8|
      Hyperplasia, Lymphoid                |                                                                          |      5  1.8|
      Hyperplasia, Plasma Cell             |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                        2                                 |      2  2.0|
      Hematopoietic Cell Proliferation     | 2        2           4  1  2  3     3     3  2  2     2        2     1  1|     30  2.5|
      Hyperplasia, Lymphoid                |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  I  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|  46        |
      Atrophy                              |             3  2  2                 4     2           2  2               |     21  2.5|
      Cyst                                 |    2                                                                     |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  M  M  M  M  +  M  M  M  M  M  M  +  M  M  +  M  M  M  M  M  M  M  M  M|   3        |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Subcutaneous Tissue, Edema           |                                                                          |      1  3.0|
      Subcutaneous Tissue, Inflammation,   |                                                                          |            |
           Acute                           |                                                                          |      1  2.0|
      Subcutaneous Tissue, Inflammation,   |                                                                          |            |
           Chronic Active                  |                      4                                                   |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   3        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                                                                          |      1  2.0|
      Mineralization                       |    1     1     2                 3  2  1  2  3     2  2  1  2           1|     27  1.8|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                                          |   1        |
      Sciatic, Degeneration                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  47                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 0| 6| 6| 5| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 7| 5| 7| 7| 5| 7| 7| 7|            |
                             DAY ON TEST   | 2| 8| 0| 9| 7| 9| 2| 2| 2| 1| 2| 2| 4| 4| 2| 2| 2| 2| 4| 2| 2| 9| 2| 2| 2|            |
                                           | 2| 7| 8| 6| 4| 5| 2| 2| 2| 5| 2| 3| 5| 9| 2| 2| 2| 2| 6| 3| 3| 1| 2| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 1|      A     |
    250 PPM                                | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 NERVOUS SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |       2                                                                  |      1  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                      1                                   2              3|      4  1.8|
      Alveolar Epithelium, Hyperplasia     |          2                                                              2|      8  1.4|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                  2                                      2|      2  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         | 1        2  1  1     2  2  2        2  1  2  2     2        1  1  2  2  2|     31  1.7|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         |          1     1  2                                         1     2      |     10  1.3|
      Respiratory Epithelium, Hyperplasia  |             2        1        1  2  2  1  1        2     2  1  1  2     1|     22  1.3|
      Respiratory Epithelium, Inflammation,|                                                                          |            |
           Chronic Active                  |                                     2                                    |      1  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                         1                                3               |      2  2.0|
      Fibrosis                             |                                           2                              |      1  2.0|
      Infarct                              |                                              2                           |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                                          |      1  2.0|
      Mineralization                       |                         1                             1                  |      3  1.0|
      Nephropathy                          |                   1        2  1              2  2        1  1  1  2  1  2|     27  1.4|
      Renal Tubule, Accumulation, Hyaline  |                                                                          |            |
          Droplet                          |                                                                          |      1  2.0|
      Renal Tubule, Dilatation             |                                     3                                    |      1  3.0|
      Renal Tubule, Pigmentation           |                      2                    3     2                        |      5  2.8|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |                               1                             1     1  2   |      7  1.1|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  48                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 2| 7| 7| 7| 0| 6|             
                             DAY ON TEST   | 1| 2| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 5| 1| 2| 2| 2| 2| 2| 2| 2| 0| 3|             
                                           | 3| 2| 3| 8| 4| 2| 2| 2| 2| 2| 2| 2| 2| 2| 7| 4| 2| 2| 2| 6| 2| 2| 2| 3| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | A  +  A  +  M  +  +  +     M  +  +  +  +  A  +  M  +  M  +  M  +  M  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +     +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  +  +  A  A  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Lymphoid Tissue, Hyperplasia         |                2     2                                                   |             
      Lymphoid Tissue, Necrosis            |                                              2                           |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | A  +  +  +  A  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  +  +  +  A  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Peyer's Patch, Hyperplasia, Lymphoid |                2                                      4                  |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  A  A  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Clear Cell Focus                     |                                                                          |             
      Cyst                                 |                                                                          |             
      Eosinophilic Focus                   | X  X           X  X              X     X     X                          X|             
      Hematopoietic Cell Proliferation     |    1                                                                     |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis                             |                                           2  2                           |             
                                            __________________________________________________________________________|             
   Mesentery                               |                               +     +                                    |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |                                                    4                     |             
      Acinus, Cytoplasmic Alteration       |                                              3                           |             
      Duct, Cyst                           |                                                    4                     |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    1  1  1  1  1              1  2           2  1  1        2     1     1|             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                          2               |             
      Epithelium, Hyperplasia              |                                                          2               |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Necrosis                             |          2                                2  2                           |             
      Glands, Dysplasia                    |    2                                         1                           |             
                                            __________________________________________________________________________|             
   Tooth                                   |                                                             +            |             
      Developmental Malformation           |                                                             1            |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  M  +  +  +  M  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               |                   1  1                          1                        |             
      Hyperplasia                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  49                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 2| 7| 7| 7| 0| 6|             
                             DAY ON TEST   | 1| 2| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 5| 1| 2| 2| 2| 2| 2| 2| 2| 0| 3|             
                                           | 3| 2| 3| 8| 4| 2| 2| 2| 2| 2| 2| 2| 2| 2| 7| 4| 2| 2| 2| 6| 2| 2| 2| 3| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Capsule, Hyperplasia                 | 1  3     1  1  2  1  3     1  1  1        1     1  1        1  1  2     1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                        2                                 |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  M  +  M  +  +  +     +  M  +  +  M  +  +  +  +  +  +  M  +  M  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  M  +  +  +  +  +     +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
      Pars Distalis, Hyperplasia           |                      2                                                   |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Follicular Cell, Hyperplasia         |    3        4        1              2           1  3        1  2  1      |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                                        1        1  1                     |             
                                            __________________________________________________________________________|             
   Penis                                   |                                                          +               |             
      Inflammation, Chronic Active         |                                                          2               |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3  4  3  2  4  4  3  4     4  4  3  4  4  4  2  4     4  2  2  3  3     3|             
      Cyst                                 | 2  4     3     3  2        2     1     4        4     4        4  2     2|             
      Inflammation, Chronic                |                   2        2     2              2           3     1      |             
      Inflammation, Chronic Active         |                                                    4                    4|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +     +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                               1                 1  1        1            |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Lymph Node                              |                            +              +                              |             
      Renal, Hemorrhage                    |                                           4                              |             
      Renal, Necrosis                      |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Necrosis                             |                                              2                           |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     |                                     2              2                     |             
      Hemorrhage                           |          2  2                             3        1           3         |             
      Hyperplasia, Histiocytic             |                                                                          |             
      Hyperplasia, Lymphoid                |                2                                            2            |             
      Necrosis                             |                                              2                           |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  50                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 2| 7| 7| 7| 0| 6|             
                             DAY ON TEST   | 1| 2| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 5| 1| 2| 2| 2| 2| 2| 2| 2| 0| 3|             
                                           | 3| 2| 3| 8| 4| 2| 2| 2| 2| 2| 2| 2| 2| 2| 7| 4| 2| 2| 2| 6| 2| 2| 2| 3| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Atrophy                              |                                           3                              |             
      Hematopoietic Cell Proliferation     |    2  3  1           1     2  2  2  4  2        2  3  4        2  4     3|             
      Hyperplasia, Lymphoid                |             4                                                            |             
      Necrosis                             |                                              2                           |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  M  +  M  +  +  +     +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Atrophy                              |                      1              1  3  2  3  1     2        2  2     2|             
      Necrosis                             |                                              3                           |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  M  M  M  M  M  M  M     M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization                       |       2  1  1  2  1           2  2  3  1  1  2              1     2     2|             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                                         +|             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                      2   |             
      Infiltration Cellular, Lymphocyte    |                                                                1         |             
      Alveolar Epithelium, Hyperplasia     |                                                                          |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                      3                             2           1         |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         |    1  1     2     2  2     3  2  2  2  3  1     2  2  1     2  2  1     1|             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         | 1  1  1  1        1           2  2        1     2              1         |             
      Respiratory Epithelium, Hyperplasia  |    1           1                                                         |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Infarct                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  51                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 5| 7| 7| 7| 2| 7| 7| 7| 0| 6|             
                             DAY ON TEST   | 1| 2| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 5| 1| 2| 2| 2| 2| 2| 2| 2| 0| 3|             
                                           | 3| 2| 3| 8| 4| 2| 2| 2| 2| 2| 2| 2| 2| 2| 7| 4| 2| 2| 2| 6| 2| 2| 2| 3| 0|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    500 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Infiltration Cellular, Lymphocyte    |                                                                          |             
      Nephropathy                          |          1     1     2        1  2  1           2  1  3     1  2        2|             
      Renal Tubule, Dilatation             |       3                                                              2   |             
      Renal Tubule, Hyperplasia            |                                           2                              |             
      Renal Tubule, Pigmentation           |             4                                                     3      |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | A  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |                      1           1                 1        1     1      |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  52                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 7| 7| 7| 6| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 8| 2| 2| 2| 4| 2| 2| 2| 2| 3| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 4| 2| 2|            |
                                           | 6| 6| 2| 2| 2| 2| 2| 2| 2| 2| 7| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|      A     |
    500 PPM                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | A  M  M  +  +  M  +  +  M  A  +  A  M  +  +  +  +  +  +  +  +  +  A  +  M|  30        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | A  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  46        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  A  +  +  +  M  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|  42        |
      Lymphoid Tissue, Hyperplasia         |                                                                          |      2  2.0|
      Lymphoid Tissue, Necrosis            |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | A  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|  43        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | A  +  +  +  +  A  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|  42        |
      Peyer's Patch, Hyperplasia, Lymphoid |                                        4                                 |      3  3.3|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | A  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|  43        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Clear Cell Focus                     |                                                 X                        |      1     |
      Cyst                                 |                      2                                                   |      1  2.0|
      Eosinophilic Focus                   |    X              X  X  X        X  X  X  X     X        X               |     18     |
      Hematopoietic Cell Proliferation     |                                                                          |      1  1.0|
      Mixed Cell Focus                     |                                                    X                     |      1     |
      Necrosis                             | 3              4                 2                             4     4   |      7  3.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |    +              +           +                 +                        |   6        |
      Fat, Necrosis                        |                                                 2                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  48        |
      Acinus, Atrophy                      |                                                                          |      1  4.0|
      Acinus, Cytoplasmic Alteration       |                                                                          |      1  3.0|
      Duct, Cyst                           |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |    1                    1  1  1     2  3  2  1  1     2     1  2     1   |     26  1.3|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  48        |
      Inflammation, Chronic Active         |          2                                                               |      2  2.0|
      Epithelium, Hyperplasia              |          3                                                               |      2  2.5|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  48        |
      Necrosis                             |    1                                                                     |      4  1.8|
      Glands, Dysplasia                    |                                                                          |      2  1.5|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                                                                          |   1        |
      Developmental Malformation           |                                                                          |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cardiomyopathy                       |                                           1                              |      1  1.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  53                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 7| 7| 7| 6| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 8| 2| 2| 2| 4| 2| 2| 2| 2| 3| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 4| 2| 2|            |
                                           | 6| 6| 2| 2| 2| 2| 2| 2| 2| 2| 7| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|      A     |
    500 PPM                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cytoplasmic Alteration               |       1              2                          1  1           1     1   |      9  1.1|
      Hyperplasia                          |       1                                               1                  |      2  1.0|
      Capsule, Hyperplasia                 |    1                 1  1              1  1  1  1  1  1  1  1  3     1   |     30  1.3|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  48        |
      Hyperplasia                          |          2                                                               |      2  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  M  +  +  +  M  +|  40        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  I  +  +|  45        |
      Pars Distalis, Hyperplasia           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Follicular Cell, Hyperplasia         |       3  2  2     1        1           1  1     1     1  2           2   |     20  1.8|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tissue NOS                              |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Infiltration Cellular, Lymphocyte    |                                              1                           |      4  1.0|
                                            __________________________________________________________________________|____________|
   Penis                                   |                                                                          |   1        |
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              | 3  3  4  4  3  4  4  3  3  3  3  3  4  4  3  4  2  3  4  3  3  4  3  2  4|     47  3.3|
      Cyst                                 | 3  3  4     3        2  4  4  3     4  2  2  4  4     4  4  4  4  4     4|     32  3.2|
      Inflammation, Chronic                |                      2  2     2           2  1  2                    2   |     13  1.9|
      Inflammation, Chronic Active         |                2                                                         |      3  3.3|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Chronic                |          1              1           1  1     1        1                  |     10  1.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |                               2                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Lymph Node                              |             +                 +                                          |   4        |
      Renal, Hemorrhage                    |             2                                                            |      2  3.0|
      Renal, Necrosis                      |             4                                                            |      1  4.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  54                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 7| 7| 7| 6| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 8| 2| 2| 2| 4| 2| 2| 2| 2| 3| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 4| 2| 2|            |
                                           | 6| 6| 2| 2| 2| 2| 2| 2| 2| 2| 7| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|      A     |
    500 PPM                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Hyperplasia, Lymphoid                |                                                          2               |      1  2.0|
      Necrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | A  +  +  +  +  +  M  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  44        |
      Hematopoietic Cell Proliferation     |                                     2           1        2           2   |      6  1.8|
      Hemorrhage                           |          2     1                    1           2                    2   |     10  1.9|
      Hyperplasia, Histiocytic             |                      2                                                   |      1  2.0|
      Hyperplasia, Lymphoid                |                                                    2                     |      3  2.0|
      Necrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  47        |
      Atrophy                              |                            3     3                                       |      3  3.0|
      Hematopoietic Cell Proliferation     |          3  3     4     2     3     4  2  1  1        1                 2|     26  2.4|
      Hyperplasia, Lymphoid                |                                                                          |      1  4.0|
      Necrosis                             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  M  M  +  M  M  M  +  M  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|  39        |
      Atrophy                              | 3  2        1                    3  3                    2               |     16  2.1|
      Necrosis                             |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|            |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                               +                                          |   2        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Mineralization                       | 1        2  1     1  3  2  2  1  2     2     1        1  2  2  2  2      |     30  1.7|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Congestion                           |                                                                          |      1  2.0|
      Infiltration Cellular, Lymphocyte    |                                                    1                     |      2  1.0|
      Alveolar Epithelium, Hyperplasia     |                                        2                                 |      1  2.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                                    3                     |      4  2.3|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  55                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 5| 7| 7| 7| 6| 7| 7| 7| 7| 6| 6| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 8| 2| 2| 2| 4| 2| 2| 2| 2| 3| 6| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 4| 2| 2|            |
                                           | 6| 6| 2| 2| 2| 2| 2| 2| 2| 2| 7| 1| 2| 2| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|      A     |
    500 PPM                                | 2| 2| 2| 2| 3| 3| 3| 3| 3| 3| 3| 3| 3| 3| 4| 4| 4| 4| 4| 4| 4| 4| 4| 4| 5|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |       2  2  2  2  2     2  2     2  2  2  3  1  1     3  2        1     2|     35  1.9|
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         |       2  2     2                                            1        1   |     15  1.4|
      Respiratory Epithelium, Hyperplasia  |          2           1  1  1           2     1     1  1        1         |     11  1.2|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  48        |
      Cyst                                 |                   2                                   1  2     2         |      4  1.8|
      Infarct                              |                      1                          1                        |      2  1.0|
      Infiltration Cellular, Lymphocyte    |                                              1                       1   |      2  1.0|
      Nephropathy                          |       2  1  1     3  1  1           1  1        1  1  1        1        2|     25  1.4|
      Renal Tubule, Dilatation             |                                                                          |      2  2.5|
      Renal Tubule, Hyperplasia            |                                                                          |      1  2.0|
      Renal Tubule, Pigmentation           | 3                                                                        |      3  3.3|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | A  +  +  +  +  +  +  +  +  A  M  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  44        |
      Infiltration Cellular, Lymphocyte    |       1  1  1                                            2               |      9  1.1|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  56                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 6| 7| 0| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 0| 7| 0| 5| 7| 4| 6| 4|             
                             DAY ON TEST   | 2| 2| 9| 8| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 5| 2| 0| 9| 2| 0| 4| 3|             
                                           | 2| 2| 9| 6| 2| 3| 5| 2| 2| 2| 2| 3| 2| 2| 2| 9| 3| 9| 3| 9| 4| 2| 6| 9| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    1000 PPM                               | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Gallbladder                             | +  +  +  M  +  +  A  +  +  +  +  +  +  +  +  A  +  +  M  A  +  +  A  A  M|             
      Hyperplasia                          |                         4                                                |             
      Ulcer                                |                         4                                                |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  A|             
      Lymphoid Tissue, Hyperplasia         |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +  A  +  A|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  A  +  A|             
      Peyer's Patch, Hyperplasia, Lymphoid |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  A  A  +  A  +  A|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Clear Cell Focus                     |                      X                                         X         |             
      Eosinophilic Focus                   |             X        X                 X        X     X              X   |             
      Infiltration Cellular, Mixed Cell    |                                                                      2   |             
      Mixed Cell Focus                     |                                        X                                 |             
      Necrosis                             |             4     4     4                                   4           2|             
      Centrilobular, Hypertrophy           |                                                                          |             
      Centrilobular, Vacuolization         |                                                                          |             
          Cytoplasmic                      |                                  2                    1        4         |             
      Periportal, Vacuolization Cytoplasmic|                                                 2  1                     |             
                                            __________________________________________________________________________|             
   Mesentery                               |       +                                      +                           |             
      Fat, Necrosis                        |                                              4                           |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Acinus, Atrophy                      |                                                                          |             
      Acinus, Cytoplasmic Alteration       |                2                                                         |             
      Duct, Cyst                           |                            2                                             |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1  1     1  1     2  1     1  1  1  1  1  2  1  1     1        1  1  2   |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A|             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Chronic Active         |          1                                                               |             
      Ulcer                                |                                                             2            |             
      Epithelium, Hyperplasia              |                                                             2            |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  A|             
      Necrosis                             |                                                    1                     |             
                                            __________________________________________________________________________|             
   Tooth                                   |                                           +                    +         |             
      Developmental Malformation           |                                           1                    1         |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Thrombosis                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  57                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 6| 7| 0| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 0| 7| 0| 5| 7| 4| 6| 4|             
                             DAY ON TEST   | 2| 2| 9| 8| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 5| 2| 0| 9| 2| 0| 4| 3|             
                                           | 2| 2| 9| 6| 2| 3| 5| 2| 2| 2| 2| 3| 2| 2| 2| 9| 3| 9| 3| 9| 4| 2| 6| 9| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    1000 PPM                               | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cytoplasmic Alteration               | 1  1        1        1              1                          2         |             
      Vacuolization Cytoplasmic            |                                                                          |             
      Capsule, Hyperplasia                 | 2  1     1  1              2  2     1  1  1  1  1     1        1         |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  M  +  +  +  +  M  +  +  +  +  +  M  M  +  M  +  +  M  +  M  M  +  +  +|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Follicular Cell, Hyperplasia         | 2                       2           1  1        1     1                  |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Peritoneum                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    |    1              2                                                      |             
      Inflammation, Granulomatous          |             3                                                            |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2  3  3     2     2  2  3  3     4  3  2     3        3     3     2  3  1|             
      Cyst                                 | 2  2        4     2     3  2  4  4  2  4     3        3        4         |             
      Inflammation, Chronic                | 3  2              2  1     2        2     2                              |             
      Inflammation, Chronic Active         |                               4              2                    1      |             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                 1                        |             
      Inflammation, Chronic                | 1  1              1        1  1                                          |             
      Inflammation, Chronic Active         |                                                             2            |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Myeloid Cell, Hyperplasia            |                               2                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |                                                                          |             
      Renal, Hemorrhage                    |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Lymphoid                |             2                                                            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Hemorrhage                           | 2        3  1     2                             1                    2   |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  58                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 6| 7| 0| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 0| 7| 0| 5| 7| 4| 6| 4|             
                             DAY ON TEST   | 2| 2| 9| 8| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 5| 2| 0| 9| 2| 0| 4| 3|             
                                           | 2| 2| 9| 6| 2| 3| 5| 2| 2| 2| 2| 3| 2| 2| 2| 9| 3| 9| 3| 9| 4| 2| 6| 9| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    1000 PPM                               | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +|             
      Hematopoietic Cell Proliferation     | 3     1  2        2     4  4     1  1  2        2                        |             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Atrophy                              | 2  3     4        3        2  2  2  2     1                              |             
      Necrosis                             |                                                          3               |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Mineralization                       | 2  1  2  1  2        2  1  2  2  2     2  1  1  2     2     2  2     2   |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                    2     2               |             
      Alveolar Epithelium, Hyperplasia     |                                                                          |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |             2                                                            |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Olfactory Epithelium, Degeneration,  |                                                                          |             
           Hyaline                         |    2                          2                 2                        |             
      Respiratory Epithelium, Degeneration,|                                                                          |             
           Hyaline                         |                               1                                          |             
      Respiratory Epithelium, Hyperplasia  |    1                          1  1  1                 1        2         |             
      Respiratory Epithelium, Inflammation,|                                                                          |             
           Chronic Active                  |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |             +                                                            |             
      Cornea, Inflammation, Chronic Active |             4                                                            |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |             +                                                            |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  59                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 7| 6| 6| 7| 0| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 0| 7| 0| 5| 7| 4| 6| 4|             
                             DAY ON TEST   | 2| 2| 9| 8| 2| 0| 6| 2| 2| 2| 2| 2| 2| 2| 2| 3| 2| 5| 2| 0| 9| 2| 0| 4| 3|             
                                           | 2| 2| 9| 6| 2| 3| 5| 2| 2| 2| 2| 3| 2| 2| 2| 9| 3| 9| 3| 9| 4| 2| 6| 9| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    1000 PPM                               | 5| 5| 5| 5| 5| 5| 5| 5| 5| 6| 6| 6| 6| 6| 6| 6| 6| 6| 6| 7| 7| 7| 7| 7| 7|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Infarct                              |       4                    1        1                                    |             
      Infiltration Cellular, Lymphocyte    |             2                             1     1                 1      |             
      Nephropathy                          | 1     2     2        1     1  1  1  1  1  1     1     1     1  1         |             
      Renal Tubule, Dilatation             |                1           1                 1     1     2               |             
      Renal Tubule, Hyperplasia            |                                                                          |             
      Renal Tubule, Pigmentation           |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Infiltration Cellular, Lymphocyte    | 1     1                 1                                      1         |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  60                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 2| 2| 2| 2| 2| 2| 2| 0| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2| 2| 2| 8| 2| 2|            |
                                           | 2| 2| 2| 2| 2| 2| 2| 2| 9| 2| 2| 2| 2| 2| 2| 2| 2| 3| 4| 2| 3| 2| 0| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|      A     |
    1000 PPM                               | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM                         |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Gallbladder                             | +  +  +  M  +  M  M  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  A  +  +|  36        |
      Hyperplasia                          |                                                                          |      1  4.0|
      Ulcer                                |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +|  45        |
      Lymphoid Tissue, Hyperplasia         |                                              1                           |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|  44        |
      Peyer's Patch, Hyperplasia, Lymphoid |                            1                                             |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +|  44        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Clear Cell Focus                     |                                                                          |      2     |
      Eosinophilic Focus                   |    X  X        X        X        X     X        X  X        X            |     15     |
      Infiltration Cellular, Mixed Cell    |                                                                          |      1  2.0|
      Mixed Cell Focus                     |                                                                          |      1     |
      Necrosis                             |                         3                                                |      6  3.5|
      Centrilobular, Hypertrophy           |                                                                         3|      1  3.0|
      Centrilobular, Vacuolization         |                                                                          |            |
          Cytoplasmic                      |       3              2                                                  2|      6  2.3|
      Periportal, Vacuolization Cytoplasmic|                                                                          |      2  1.5|
                                            __________________________________________________________________________|____________|
   Mesentery                               |       +                                                           +      |   4        |
      Fat, Necrosis                        |       3                                                                  |      2  3.5|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Acinus, Atrophy                      |                         2                                                |      1  2.0|
      Acinus, Cytoplasmic Alteration       |                                                                          |      1  2.0|
      Duct, Cyst                           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    | 1  2     1  1     2  1  1     1     1  1     1  1  1  1  1     2         |     34  1.2|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Inflammation, Chronic                |                                                                   1      |      1  1.0|
      Inflammation, Chronic Active         |                                                       1                  |      2  1.0|
      Ulcer                                |                                                                          |      1  2.0|
      Epithelium, Hyperplasia              |                                                       2                  |      2  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Necrosis                             |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                                           +                              |   3        |
      Developmental Malformation           |                                           4                              |      3  2.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  61                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 2| 2| 2| 2| 2| 2| 2| 0| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2| 2| 2| 8| 2| 2|            |
                                           | 2| 2| 2| 2| 2| 2| 2| 2| 9| 2| 2| 2| 2| 2| 2| 2| 2| 3| 4| 2| 3| 2| 0| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|      A     |
    1000 PPM                               | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 ALIMENTARY SYSTEM - cont                  |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Thrombosis                           |                         4                                                |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +|  49        |
      Cytoplasmic Alteration               |       1     1        1        2           1                              |     11  1.2|
      Vacuolization Cytoplasmic            |                         2                                                |      1  2.0|
      Capsule, Hyperplasia                 | 2  2  1  1  2              1  1  1  2           1  2  1  2  1  1        1|     29  1.3|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  M  M  +  +  M  +  +  M  M  M  +  +  M  +  +  M  M  +  M  +  +  M  +  +|  31        |
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  I  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Follicular Cell, Hyperplasia         |       2                       1        1     1  2              1         |     12  1.3|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Peritoneum                              |                                                                   +      |   1        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |                1                                      1                  |      4  1.3|
      Inflammation, Granulomatous          |                            3                    4                        |      3  3.3|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              | 2  3  2  4  3  3  3  3  4  4  3  4  2  2  4  3  3  4  4  4  3  3  4  4  3|     42  3.0|
      Cyst                                 |       4  3     4  4  4     4  2  4     1  2     4  3        3        3  2|     28  3.1|
      Inflammation, Chronic                |       2  1                 1  2                       1                  |     12  1.8|
      Inflammation, Chronic Active         |    2              3                                                  3   |      6  2.5|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |                                                                          |      1  1.0|
      Inflammation, Chronic                |                1           1  1                                          |      8  1.0|
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                         1                                                |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  62                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 2| 2| 2| 2| 2| 2| 2| 0| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2| 2| 2| 8| 2| 2|            |
                                           | 2| 2| 2| 2| 2| 2| 2| 2| 9| 2| 2| 2| 2| 2| 2| 2| 2| 3| 4| 2| 3| 2| 0| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|      A     |
    1000 PPM                               | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Myeloid Cell, Hyperplasia            |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |                                                             +     +      |   2        |
      Renal, Hemorrhage                    |                                                             2            |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                         2                                                |      1  2.0|
      Hematopoietic Cell Proliferation     |             1                                                            |      1  1.0|
      Hemorrhage                           |                2     2  2        3     1                                2|     12  1.9|
      Hyperplasia, Lymphoid                | 2                                   3        2  2                        |      4  2.3|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hematopoietic Cell Proliferation     |          3     1  1     4     2  2           3  3     2     1  3  2  1   |     23  2.2|
      Hyperplasia, Lymphoid                |                                                          2               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Atrophy                              | 1        1                                2  3        2           3  3   |     16  2.3|
      Necrosis                             |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M  M|            |
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                   +      |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Mineralization                       | 2     2        2  1  2  2     2  2  2  1     2     2  2  2  2  1     2   |     35  1.8|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      2  2.0|
      Alveolar Epithelium, Hyperplasia     |                               1                    1                     |      2  1.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Olfactory Epithelium, Degeneration,  |                                                                          |            |
           Hyaline                         |                            2     2     1                             1   |      7  1.7|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  63                                                               
NTP Experiment-Test: 55301-04                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 11/19/96  
Route: DOSED WATER                                                                                                Time: 15:53:54  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 7| 6| 7| 7| 7| 7| 7| 6| 7| 7| 7| 6| 7| 7|            |
                             DAY ON TEST   | 2| 2| 2| 2| 2| 2| 2| 2| 0| 2| 2| 2| 7| 2| 2| 2| 2| 2| 2| 2| 2| 2| 8| 2| 2|            |
                                           | 2| 2| 2| 2| 2| 2| 2| 2| 9| 2| 2| 2| 2| 2| 2| 2| 2| 3| 4| 2| 3| 2| 0| 2| 2|      T (*) |
 _____________________________________________________________________________________________________________________|            |
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      O     |
   B6C3F1 MICE MALE                        | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      T     |
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2|      A     |
    1000 PPM                               | 7| 7| 7| 7| 8| 8| 8| 8| 8| 8| 8| 8| 8| 8| 9| 9| 9| 9| 9| 9| 9| 9| 9| 9| 0|      L     |
                                           | 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0|            |
 __________________________________________________________________________________________________________________________________ 
 RESPIRATORY SYSTEM - cont                 |                                                                          |            |
                                           |                                                                          |            |
      Respiratory Epithelium, Degeneration,|                                                                          |            |
           Hyaline                         |                                     1                                    |      2  1.0|
      Respiratory Epithelium, Hyperplasia  |    2     2     1           2     1                 1     1  1     1      |     15  1.3|
      Respiratory Epithelium, Inflammation,|                                                                          |            |
           Chronic Active                  |                                                                1         |      1  1.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Eye                                     |                                                                          |   1        |
      Cornea, Inflammation, Chronic Active |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                           4                              |      1  4.0|
      Infarct                              |                                                    1     1  2            |      6  1.7|
      Infiltration Cellular, Lymphocyte    |                                        4                 1               |      6  1.7|
      Nephropathy                          |    2  1  1  1  2  1     2  1  1  3     2  1  1     2        1  1     3  3|     32  1.4|
      Renal Tubule, Dilatation             |                                                                          |      5  1.2|
      Renal Tubule, Hyperplasia            |                      2                                                   |      1  2.0|
      Renal Tubule, Pigmentation           |                         3                             2                  |      2  2.5|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Infiltration Cellular, Lymphocyte    |          1                 1  1                                1         |      8  1.0|
 __________________________________________________________________________________________________________________________________ 

  * : Total animals with tissue examined microscopically; total animals with lesion and mean severity grade                         
  + : Tissue examined microscopically                M : Missing tissue                        1-4 : Lesion qualified as:           
  X : Lesion present but not qualified               A : Autolysis precludes examination               1) Minimal  3) Moderate      
  I : Insufficient tissue                        BLANK : Not examined                                  2) Mild     4) Marked        

                                                             Page  64                                                               
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