Skip to Main Navigation
Skip to Page Content
Share This:
https://ntp.niehs.nih.gov/go/5366

TDMS Study 55301-06 Pathology Tables

NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97
Route: DOSED WATER                                                                                                Time: 12:22:11




       Facility:  TSI Mason Research

       Chemical CAS #:  110-86-1

       Lock Date:  12/13/94

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All






































                                                              Page   1


NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM                         |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Esophagus                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | +  +  A  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  A  +  A  A  A|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  A  +  +  A  A|             
      Hemorrhage                           |                                                                   2      |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | +  +  A  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  A  +  M  +  A  A  A|             
      Hemorrhage                           |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  A  +  +  +  +  +  +  +  +  +  +  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  A  A|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                          2               |             
      Clear Cell Focus                     |    X     X  X  X           X  X  X        X  X  X  X                     |             
      Congestion                           | 3           2                                   3     3     4  2  4  3  4|             
      Degeneration, Cystic                 |                                                          2               |             
      Eosinophilic Focus                   |    X     X  X           X  X     X           X           X               |             
      Fibrosis                             |                                                             2            |             
      Hemorrhage                           |                                                                      3   |             
      Hepatodiaphragmatic Nodule           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Mixed Cell Focus                     |                                                                          |             
      Necrosis                             |                                                                          |             
      Pigmentation                         |       1                    3                                             |             
      Vacuolization Cytoplasmic            |          1        1        1        4  1                 1  2     2      |             
      Bile Duct, Hyperplasia               |    1  1  1  1  1     2  3  1  1  1           1  1  2  1  2     1         |             
      Centrilobular, Degeneration          |                                                                          |             
      Centrilobular, Necrosis              |                                                       3     2     3  3   |             
      Hepatocyte, Atrophy                  |                                                                          |             
      Oval Cell, Hyperplasia               |                                                                          |             
      Sinusoid, Congestion                 |                   2                                                      |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                     +  +              +     +            |             
      Mineralization                       |                                        2                                 |             
      Artery, Inflammation                 |                                     4  3              2     4            |             
      Artery, Mineralization               |                                                       2                  |             
      Fat, Necrosis                        |                                                                          |             
                                            __________________________________________________________________________|             
   Oral Mucosa                             | +           +        +                    +                              |             
      Inflammation, Suppurative            |             1        2                                                   |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  A  +  +|             
      Atrophy                              |                                     1                                    |             
      Basophilic Focus                     |                         X                                                |             
      Hyperplasia                          |    4     3           3           3           4  4  4     4               |             
      Necrosis                             |                                                                         1|             
      Acinus, Hyperplasia                  |                                                                          |             
      Artery, Inflammation                 |                      3                                                   |             
      Artery, Mineralization               |                                                       2                  |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   2                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
      Duct, Hyperplasia                    |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Artery, Mineralization               |                                        3                                 |             
      Duct, Cyst                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                                                          |             
      Hyperplasia, Squamous                |                                     3                                    |             
      Inflammation, Acute                  |                                                                          |             
      Mineralization                       |                                                                          |             
      Ulcer, Chronic                       |                                     4                                    |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Erosion                              |       2                                                                  |             
      Hyperplasia                          |                                                                          |             
      Mineralization                       |       3                                4              2                  |             
                                            __________________________________________________________________________|             
   Tooth                                   |                                                          +               |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Chronic Active                  |                                                                          |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Suppurative                     |                                                          3               |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            |       +                             +  +              +                  |             
      Mineralization                       |                                     2  4                                 |             
      Aorta, Mineralization                |       3                                4              2                  |             
      Pulmonary Artery, Mineralization     |                                        4              3                  |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 3  2  3  2  2  2  2  2  2  2  3  3  1  4  2  2  3  1  4  3  3     1  4  3|             
      Inflammation, Chronic                |                                                                          |             
      Mineralization                       |       1                                2              1                  |             
      Thrombosis                           |                                                                2         |             
      Artery, Mineralization               |                                                       2                  |             
      Artery, Thrombosis                   |                                                                          |             
      Atrium, Thrombosis                   |                                                       4           2  4   |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Accessory Adrenal Cortical Nodule    |                                                       2                  |             
      Angiectasis                          |                                                                         2|             
      Hemorrhage                           |                                                       2  2           3   |             
      Hyperplasia                          |    4                                                                     |             
      Hypertrophy                          |                                  1                                      2|             
      Vacuolization Cytoplasmic            | 2        1                    2                 1     2  1     2  2  2   |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page   3                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM - cont                   |                                                                          |             
                                           |                                                                          |             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  A  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Hyperplasia                          |       4                                4              4  2     2         |             
      Inflammation, Chronic                |                                                                          |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                      2     2                 3           2     3     2  2|             
      Hyperplasia                          | 3           3           1                          3     2        2  1   |             
      Pars Distalis, Hyperplasia           |                                           2  2                           |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Follicle, Cyst                       |                                           3                              |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Arteriole, Mineralization            |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                                             1            |             
      Inflammation, Chronic Active         |                            2                                             |             
      Inflammation, Suppurative            |    2     2                          3     4        4                     |             
      Duct, Cyst                           | 2  2  3  2  2  2     2  1  3  1  2  4  1  1  3  4  3  2  2  2  2  1  2  1|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |    3                                                                     |             
      Hyperplasia                          |    2     1                 1              1                              |             
      Inflammation, Acute                  | 2     1        1     1                                                   |             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Chronic Active         |                         1           1                 2                  |             
      Artery, Mineralization               |                                                       1                  |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       2              4              3           1     4        1  1  4   |             
      Mineralization                       |    1  1                                1                                 |             
      Artery, Inflammation                 |       2              2     2        2     3        1  4                 3|             
      Interstitial Cell, Hyperplasia       |                   2     4                                                |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Myeloid Cell, Hyperplasia            |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              | +  +     +           +           +  +  +  +        +  +  +     +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page   4                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Ectasia                              |                                                       2  2               |             
      Hemorrhage                           |                                                       2  3               |             
      Hyperplasia, Plasma Cell             |                                                          3               |             
      Iliac, Ectasia                       |    3                                                  3                  |             
      Iliac, Hemorrhage                    |                                                       2                  |             
      Inguinal, Atrophy                    | 2                                                                        |             
      Inguinal, Ectasia                    |                      2                                                   |             
      Mediastinal, Congestion              |                                        2                                 |             
      Mediastinal, Ectasia                 |          1           2                                            2  2   |             
      Mediastinal, Hemorrhage              | 1                                                     4           4  2   |             
      Pancreatic, Ectasia                  |                      4                                                   |             
      Pancreatic, Hemorrhage               |                                                       3                  |             
      Pancreatic, Hyperplasia, Lymphoid    |                                  3                                       |             
      Pancreatic, Hyperplasia, Plasma Cell |                                                                          |             
      Renal, Ectasia                       |                      4              4  3              3  3           2  3|             
      Renal, Hemorrhage                    |                                     3  2              2              2   |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Ectasia                              |    2     2     2     2     1              1  1                 2     2   |             
      Hemorrhage                           |                                                                   4      |             
      Hyperplasia, Plasma Cell             | 3                                                                       3|             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  A  +  +  +  +  +  +  +  +  +  M  A  +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |                                              1  1              2         |             
      Hemorrhage                           |    2        2                                         3     1     3  3   |             
      Hyperplasia, Lymphoid                |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Angiectasis                          |                                                                          |             
      Atrophy                              |       3                                2                                 |             
      Congestion                           |                                                 3                        |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Hyperplasia, Lymphoid                |                                                          2               |             
      Necrosis                             |    1                                                                     |             
      Artery, Mineralization               |       1                                                                  |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  M  +|             
      Atrophy                              |       3        4                                      4     4     4     2|             
      Cyst                                 |                                                          2               |             
      Ectopic Parathyroid Gland            |                      2                                2                  |             
      Ectopic Thyroid                      |                                                                          |             
      Hemorrhage                           | 1           2                                                            |             
      Hyperplasia, Lymphoid                |          4                                                               |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Hyperplasia                          |       1                                                                 1|             
      Artery, Mineralization               |       1                                2                                 |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   5                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM - cont               |                                                                          |             
                                           |                                                                          |             
      Duct, Dilatation                     |          1           1              1  2                                 |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                 2                        |             
      Hyperkeratosis                       |                                                                          |             
      Inflammation, Chronic                |                                                    3                     |             
      Ulcer                                |    4                                                                     |             
      Hair Follicle, Cyst                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |       3                                4              3     2            |             
      Cranium, Fibrous Osteodystrophy      |       3                                4              3     2            |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                 +                        |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Hydrocephalus                        |                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                  +                                       |             
      Degeneration                         |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hemorrhage                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Chronic                |                         1                                                |             
      Inflammation, Granulomatous          |                                  1           1                           |             
      Necrosis                             |                                                             4            |             
      Alveolar Epithelium, Hyperplasia     |                                           2                              |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |       1     1                             2           4                  |             
      Alveolus, Mineralization             |       1                                                                  |             
      Artery, Mineralization               |       1                                                                  |             
      Bronchus, Inflammation, Acute        |                                                                          |             
      Bronchus, Mineralization             |       1                                                                  |             
      Interstitium, Fibrosis               |                                                       3     2     1      |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                  2                                       |             
      Erosion                              |                                  2                                       |             
      Foreign Body                         |                               X           X                 X        X   |             
      Hemorrhage                           |                                                 3     3                  |             
      Hyperplasia, Squamous                |                                                                      3   |             
      Inflammation, Acute                  | 1                                         1                          4   |             
      Inflammation, Chronic                |             3                 2  1  1        2  1        1               |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   6                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 5| 7| 5| 7| 6| 7| 6| 7| 7| 7| 7| 7| 4| 6| 7| 7| 7| 7| 7| 7| 7| 7| 6| 6| 7|             
                             DAY ON TEST   | 8| 2| 5| 2| 5| 2| 7| 2| 2| 2| 2| 2| 6| 0| 2| 2| 2| 2| 1| 2| 0| 2| 4| 1| 0|             
                                           | 9| 2| 7| 2| 4| 2| 6| 2| 2| 2| 2| 2| 8| 1| 2| 2| 2| 2| 7| 2| 7| 2| 4| 6| 5|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    0 PPM                                  | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM - cont                 |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic Active         |                         2                                                |             
      Olfactory Epithelium, Hyperplasia    |                               3                                          |             
      Respiratory Epithelium, Hyperplasia  |       2  1  1     1  1  2  1     2        1  1           1              3|             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                     +                                    |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                  +                                       |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           | 2  3        2                                                            |             
      Cyst                                 |       2        2     2     2              2     1           2  1  1     2|             
      Hydronephrosis                       |                      2        2                                          |             
      Mineralization                       |       1                                2              2                  |             
      Nephropathy                          | 1  3  4  3  3  4  2  4  3  3  2  3  4  4  4  3  2  3  4  3  4  3  4  4  4|             
      Artery, Mineralization               |       2                                2              2                  |             
      Renal Tubule, Hyperplasia            |                                     1                                    |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +|             
      Inflammation, Chronic                |                                                                          |             
      Transitional Epithelium, Hyperplasia |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page   7                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  A  +  +  +  +  A  A  +  +  +  +  +  +  A  +  +  +  A  A  +  A|  35        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  A  +  +  +  +  +  +  +|  42        |
      Hemorrhage                           |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  A  +  +  +  +  A  A  +  A  +  +  A  +  A  +  +  A  A  A  +  A|  32        |
      Hemorrhage                           | 2                                                                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  A  A  +  +  +  +  +  +  A  +  +  +  A  A  +  +|  39        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  A  +  A  +  +  A  A  +  +  +  +  +  +  +  +  +  +  A  A  +  +|  37        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  A  A  +  A  +  A  +  +  A  A  +  A  A  +  A  +  A  A  +  +  A  A  +  +|  28        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          | 1                          2              2                          1   |      5  1.6|
      Clear Cell Focus                     |             X           X           X     X                              |     15     |
      Congestion                           | 3     2        2           2           2           2  2     3     2     3|     19  2.7|
      Degeneration, Cystic                 |             1     1  1  3        2                                   3   |      7  1.9|
      Eosinophilic Focus                   |          X              X                       X     X  X        X      |     14     |
      Fibrosis                             |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  3.0|
      Hepatodiaphragmatic Nodule           | X                                         X                              |      2     |
      Inflammation, Acute                  |             1                                                            |      1  1.0|
      Mixed Cell Focus                     |                      X                                                   |      1     |
      Necrosis                             | 1     3                          1        1           1     3            |      6  1.7|
      Pigmentation                         | 1           2           1  1                                             |      6  1.5|
      Vacuolization Cytoplasmic            | 1  1     1  1     1  3  1  2     2                                   3   |     18  1.6|
      Bile Duct, Hyperplasia               | 1     1  2           1  1        2     1  2     1     2  1  1  2     2  1|     31  1.4|
      Centrilobular, Degeneration          |                         1                                                |      1  1.0|
      Centrilobular, Necrosis              |                                              3                           |      5  2.8|
      Hepatocyte, Atrophy                  |                                  1        2                              |      2  1.5|
      Oval Cell, Hyperplasia               |                                  3                                       |      1  3.0|
      Sinusoid, Congestion                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               | +                          +                             +               |   7        |
      Mineralization                       |                                                                          |      1  2.0|
      Artery, Inflammation                 |                            4                                             |      5  3.4|
      Artery, Mineralization               | 2                                                                        |      2  2.0|
      Fat, Necrosis                        |                                                          2               |      1  2.0|
                                            __________________________________________________________________________|____________|
   Oral Mucosa                             | +                                                                        |   5        |
      Inflammation, Suppurative            | 2                                                                        |      3  1.7|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  46        |
      Atrophy                              |                      2                                                   |      2  1.5|
      Basophilic Focus                     |                                                                          |      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   8                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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                  |                                                                          |            |
                                           |                                                                          |            |
      Hyperplasia                          | 1           4     4     3           1        1  2        3        1  3   |     18  2.9|
      Necrosis                             |                                                                          |      1  1.0|
      Acinus, Hyperplasia                  |             3                                                            |      1  3.0|
      Artery, Inflammation                 |             4                                   3                        |      3  3.3|
      Artery, Mineralization               |                3                                                         |      2  2.5|
      Duct, Hyperplasia                    |                                                 2                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|  48        |
      Artery, Mineralization               |                            2                                             |      2  2.5|
      Duct, Cyst                           |                                                                      1   |      1  1.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Erosion                              |                            3                                             |      1  3.0|
      Hyperplasia, Squamous                |                            1                                             |      2  2.0|
      Inflammation, Acute                  |                                                             1            |      1  1.0|
      Mineralization                       |                4  2        1                                             |      3  2.3|
      Ulcer, Chronic                       |                                                                          |      1  4.0|
      Ulcer                                |    3                                                              2      |      2  2.5|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Erosion                              | 2                                            2                           |      3  2.0|
      Hyperplasia                          |                                                                      1   |      1  1.0|
      Mineralization                       | 3              4  1        4                 1                           |      8  2.8|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                         +                                                |   2        |
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Chronic Active                  |                         2                                                |      1  2.0|
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Suppurative                     |                                                                          |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            |                +  +        +                                   +         |   8        |
      Mineralization                       |                3  2        4                                   2         |      6  2.8|
      Aorta, Mineralization                |                4  2        4                                   2         |      7  3.0|
      Pulmonary Artery, Mineralization     |                                                                3         |      3  3.3|
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cardiomyopathy                       | 2  3  2  4  2  3  3  3  3  3  2  3  3  2  2  3  3  3  3  1  1  3  2  2  3|     49  2.5|
      Inflammation, Chronic                |                                     4                                    |      1  4.0|
      Mineralization                       |                   1        3                                   4         |      6  2.0|
      Thrombosis                           |                                                                          |      1  2.0|
      Artery, Mineralization               |                3           4                                   2         |      4  2.8|
      Artery, Thrombosis                   |                                        2                                 |      1  2.0|
      Atrium, Thrombosis                   |                      3                                                   |      4  3.3|
 __________________________________________________________________________________________________________________________________ 

  * : 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   9                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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|            |
 __________________________________________________________________________________________________________________________________ 
 CARDIOVASCULAR SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Accessory Adrenal Cortical Nodule    |                                                                          |      1  2.0|
      Angiectasis                          |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      3  2.3|
      Hyperplasia                          |                                                                          |      1  4.0|
      Hypertrophy                          |                                                                          |      2  1.5|
      Vacuolization Cytoplasmic            |          1        1     1        3  1        1  1                 1      |     17  1.5|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                1     2                          1                        |      3  1.3|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Hyperplasia                          |                      2                                                   |      1  2.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Hyperplasia                          | 4        3  4  4  4        4                    2           2  4     4  2|     16  3.3|
      Inflammation, Chronic                |                                              3                           |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 | 2  1  1  4     1           1              1                 2        1  1|     17  1.8|
      Hyperplasia                          | 4                                   2     1     3        2  1            |     13  2.2|
      Pars Distalis, Hyperplasia           |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Follicle, Cyst                       |                                                          1               |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       | +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Chronic Active         |                                                                   2      |      1  2.0|
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Arteriole, Mineralization            | 1                                                                        |      1  1.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic                |                                                          1               |      2  1.0|
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
      Inflammation, Suppurative            |                2     2           4           4     3  2        2         |     12  2.8|
      Duct, Cyst                           | 2  2  2  2  2  3  4  2  3  3  1  2  4  4  4  3  2  2  4  1  4  4  3  3  2|     49  2.4|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                                                                          |      1  3.0|
      Hyperplasia                          |                                                                          |      4  1.3|
 __________________________________________________________________________________________________________________________________ 

  * : 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  10                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Acute                  |                                                                          |      4  1.3|
      Inflammation, Chronic                |    1     1                       2                                       |      3  1.3|
      Inflammation, Chronic Active         |                            2                                      2      |      5  1.6|
      Artery, Mineralization               |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              | 2        4  1     1        2     4        2  2  2     1     1  3         |     20  2.3|
      Mineralization                       |    1                             1              2                        |      6  1.2|
      Artery, Inflammation                 | 3     2  4  2  1  2     1  4     2  3                 3  2  1  4  2  1   |     24  2.3|
      Interstitial Cell, Hyperplasia       |                         1                                                |      3  2.3|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Myeloid Cell, Hyperplasia            |    3                                                        2            |      2  2.5|
                                            __________________________________________________________________________|____________|
   Lymph Node                              | +  +     +     +  +        +  +  +  +  +        +     +  +     +     +  +|  31        |
      Ectasia                              |                                                                          |      2  2.0|
      Hemorrhage                           |                                                                          |      2  2.5|
      Hyperplasia, Plasma Cell             |                                        3                                 |      2  3.0|
      Iliac, Ectasia                       |                4                 4     2                                 |      5  3.2|
      Iliac, Hemorrhage                    |                                                                          |      1  2.0|
      Inguinal, Atrophy                    |                                                                          |      1  2.0|
      Inguinal, Ectasia                    |                                                                          |      1  2.0|
      Mediastinal, Congestion              |                                                                          |      1  2.0|
      Mediastinal, Ectasia                 |                1                                               3         |      6  1.8|
      Mediastinal, Hemorrhage              | 1                 3                                      1     3         |      8  2.4|
      Pancreatic, Ectasia                  |                                                 3                        |      2  3.5|
      Pancreatic, Hemorrhage               | 3                                                     2              1   |      4  2.3|
      Pancreatic, Hyperplasia, Lymphoid    |                                                                      2   |      2  2.5|
      Pancreatic, Hyperplasia, Plasma Cell |                                                       2                  |      1  2.0|
      Renal, Ectasia                       | 4              4  2        4     4              3              2        4|     15  3.3|
      Renal, Hemorrhage                    | 3                 3        4                    1              2        1|     10  2.3|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|  48        |
      Ectasia                              |       2     1                    3  3                    3        2      |     15  1.9|
      Hemorrhage                           |                                  2                       1               |      3  2.3|
      Hyperplasia, Plasma Cell             |                               3                                   3      |      4  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +|  46        |
      Ectasia                              |                      4           2                                       |      5  2.0|
      Hemorrhage                           | 4  1                       1                             2  2     1      |     12  2.1|
      Hyperplasia, Lymphoid                |                                                 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  11                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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|            |
 __________________________________________________________________________________________________________________________________ 
 HEMATOPOIETIC SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Angiectasis                          |       3                                                                  |      1  3.0|
      Atrophy                              |                                                                          |      2  2.5|
      Congestion                           |                                                                          |      1  3.0|
      Hematopoietic Cell Proliferation     |                                              4                           |      1  4.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  2.0|
      Necrosis                             |                                                                          |      1  1.0|
      Artery, Mineralization               |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Atrophy                              | 4  4  4        3  4        4                 4                 4  2      |     15  3.6|
      Cyst                                 |                            4              1  1                    1      |      5  1.8|
      Ectopic Parathyroid Gland            |                                                 2                        |      3  2.0|
      Ectopic Thyroid                      |                                                 2                        |      1  2.0|
      Hemorrhage                           |                               3        2           2  1              1  2|      8  1.8|
      Hyperplasia, Lymphoid                |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Hyperplasia                          |                                                 2                       1|      4  1.3|
      Artery, Mineralization               |                            1                                             |      3  1.3|
      Duct, Dilatation                     |                                        2              3                  |      6  1.7|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      1  2.0|
      Hyperkeratosis                       |                                              2                           |      1  2.0|
      Inflammation, Chronic                |                                                                          |      1  3.0|
      Ulcer                                |                                                                          |      1  4.0|
      Hair Follicle, Cyst                  |                                                             2            |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               | 2              4  3        4                                   2     1   |     10  2.8|
      Cranium, Fibrous Osteodystrophy      | 2              4  1        4                                   1     2   |     10  2.6|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                                                       2                  |      1  2.0|
      Hydrocephalus                        |                                  1                                       |      1  1.0|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                                          |   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  12                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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|            |
 __________________________________________________________________________________________________________________________________ 
 NERVOUS SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Degeneration                         |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hemorrhage                           |                   2                                         1            |      2  1.5|
      Inflammation, Acute                  |       3                                                                  |      1  3.0|
      Inflammation, Chronic                |                                                                          |      1  1.0|
      Inflammation, Granulomatous          | 1        1                                                               |      4  1.0|
      Necrosis                             |                                                                          |      1  4.0|
      Alveolar Epithelium, Hyperplasia     |                                                                          |      1  2.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                     1  2                 2     2         |      8  1.9|
      Alveolus, Mineralization             |                                                                1         |      2  1.0|
      Artery, Mineralization               |                            3                                             |      2  2.0|
      Bronchus, Inflammation, Acute        |             4                                                            |      1  4.0|
      Bronchus, Mineralization             |                                                                          |      1  1.0|
      Interstitium, Fibrosis               |                   2                                                      |      4  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      1  2.0|
      Erosion                              |                                                                          |      1  2.0|
      Foreign Body                         |    X  X              X              X  X                 X        X      |     11     |
      Hemorrhage                           |                                  1                                       |      3  2.3|
      Hyperplasia, Squamous                |                                                                          |      1  3.0|
      Inflammation, Acute                  |    2  3                    2                                      4      |      7  2.4|
      Inflammation, Chronic                |                                                                          |      7  1.6|
      Inflammation, Chronic Active         |                      1              3                    3               |      4  2.3|
      Olfactory Epithelium, Hyperplasia    |                                                                          |      1  3.0|
      Respiratory Epithelium, Hyperplasia  |    3     2     1  2  2                    2  2              2            |     20  1.7|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |    +                                                                     |   1        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                               3                                          |      4  2.5|
      Cyst                                 | 2        2  1  3  2     2                       2     2  3     2     3   |     21  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  13                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 6| 5| 7| 6| 5| 6| 7| 7| 6| 2| 7| 5| 6| 7| 5| 7| 5| 6| 7| 6| 5| 6| 7| 5|            |
                             DAY ON TEST   | 0| 6| 9| 2| 3| 7| 1| 2| 2| 9| 8| 2| 9| 8| 2| 7| 2| 8| 7| 2| 2| 5| 4| 2| 3|            |
                                           | 1| 0| 8| 2| 9| 6| 8| 2| 2| 5| 3| 2| 2| 1| 2| 2| 2| 7| 4| 2| 4| 9| 4| 2| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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                     |                                                                          |            |
                                           |                                                                          |            |
      Hydronephrosis                       | 1     2  1  2  2     2  2  1     2     1     2  1     1  2  1        3  1|     19  1.6|
      Mineralization                       |                2  1        2                                   1     1   |      8  1.5|
      Nephropathy                          | 4  2  3  4  4  4  4  3  3  4  1  4  3  4  2  2  4  3  4  2  4  4  4  4  4|     50  3.3|
      Artery, Mineralization               |                2                                               2         |      5  2.0|
      Renal Tubule, Hyperplasia            |                3        2        1              1                    2   |      6  1.7|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +  +|  47        |
      Inflammation, Chronic                |                                  3                                       |      1  3.0|
      Transitional Epithelium, Hyperplasia |                                  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  14                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | A  +  +  +  A  +  +  +  A  A  +  +  +  +  A  +  +  +  +  A  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | A  +  +  +  A  +  +  +  A  A  +  +  +  +  A  +  +  +  +  A  +  A  +  +  +|             
      Mineralization                       |                                                             2            |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  +  +  A  A  +  +  +  A  +  +  +  +  +  A  A  +  +  +  A  +  A  +  +  +|             
      Edema                                |                                                                          |             
      Hemorrhage                           |                                                             2            |             
      Inflammation, Acute                  |                                                             2            |             
      Ulcer                                |                            4                                             |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +  A  +  +  +  +  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  +  +  A  +  +  +  A  A  +  +  +  A  A  +  A  +  +  +  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  +  A  A  +  +  +  A  A  +  +  +  A  A  +  +  +  +  A  A  A  +  +  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          | 1              1  2                    2     2                           |             
      Clear Cell Focus                     |                X                 X                 X              X     X|             
      Congestion                           | 2        3  3                 2           3              3  2            |             
      Degeneration, Cystic                 | 1     1                                   1  2              1  1     1   |             
      Eosinophilic Focus                   | X              X  X                    X           X              X      |             
      Fibrosis                             |          1     1                                                         |             
      Hemorrhage                           |                   2                                                      |             
      Hepatodiaphragmatic Nodule           |                                     X                                    |             
      Infiltration Cellular, Histiocyte    |                                                          2               |             
      Inflammation, Acute                  |                                  1                                       |             
      Mineralization                       |                                                                          |             
      Necrosis                             | 1                 4                       1        1                 3  1|             
      Pigmentation                         | 1  1     3     1  1     1           1                                1   |             
      Vacuolization Cytoplasmic            |          1        1  2  3                    1  1     2        2        1|             
      Artery, Mineralization               |                                                                          |             
      Bile Duct, Dilatation                |                                                                          |             
      Bile Duct, Hyperplasia               | 1  1  1  1     1  1  1  1  3     2  1  1  1     1  1  2     1  1  1  2  2|             
      Centrilobular, Cytomegaly            |                                                                          |             
      Centrilobular, Degeneration          |    3  3              2                 1                 1  2     1      |             
      Centrilobular, Hypertrophy           |                                                                          |             
      Centrilobular, Necrosis              |                      1     3                             2               |             
                                            __________________________________________________________________________|             
   Mesentery                               |                            +                                             |             
      Artery, Inflammation                 |                            2                                             |             
                                            __________________________________________________________________________|             
   Oral Mucosa                             |                                                                          |             
      Hyperplasia, Squamous                |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                   2                                               1  1   |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |       2  2  2     4              4              2     3           3     3|             
      Artery, Inflammation                 |                1           2                                             |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  15                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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 - cont                  |                                                                          |             
                                           |                                                                          |             
      Artery, Mineralization               |          3                                                  3  3         |             
      Duct, Hyperplasia                    |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Acute                  |                                                                          |             
      Artery, Mineralization               |          2              2                                   2            |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Squamous                |                      3     3        2  4     1  2           1  4         |             
      Mineralization                       |                         4                                   2            |             
      Ulcer                                |                            4        2           3                        |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |                                        1        2                        |             
      Fibrosis                             |                1                                                         |             
      Mineralization                       |    1  3  4  3  2  1  4  4              4        1           4  3         |             
      Serosa, Edema                        |                                                                          |             
                                            __________________________________________________________________________|             
   Tooth                                   |                                  +                                       |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Granulomatous                   |                                                                          |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Suppurative                     |                                  2                                       |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            |    +  +  +  +        +  +              +        +           +  +         |             
      Mineralization                       |                                                             4  1         |             
      Aorta, Mineralization                |    1  4  2  1        2  4              4        1           4  4         |             
      Pulmonary Artery, Degeneration       |                                                                          |             
      Pulmonary Artery, Mineralization     |                                        1                    4            |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 3  3  1  4  3  2  3  3  4  2  3  3  1  2  2  3  4  3  2  3  3  3  2  2  1|             
      Mineralization                       |    1     2              1              2        1           2  2         |             
      Artery, Inflammation                 |                                                                      3   |             
      Artery, Mineralization               |    1     1  2           2                                   4  3         |             
      Atrium, Thrombosis                   |    2                                                                     |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |    2                                                        3            |             
      Degeneration                         |    2                    2                                                |             
      Hyperplasia                          |                                                                          |             
      Hypertrophy                          |             2                                                        1   |             
      Mineralization                       |                                                             2            |             
      Thrombosis                           |                                                                          |             
      Vacuolization Cytoplasmic            |    2                 1                                1     1     1      |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                              3                           |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  16                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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                   |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                           3                              |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |    3  4  4  3  2  2     3           1  4     2  2     2     4  4  1      |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    2           2     2           2  2     2                             1|             
      Hyperplasia                          |    2     4     2              3  2     4                                 |             
      Pars Distalis, Hyperplasia           |                                     3                                    |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      C-Cell, Hyperplasia                  |                                                                          |             
      Follicle, Cyst                       |                                        1        2                        |             
      Follicular Cell, Hyperplasia         |                                           2                          2   |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Tissue NOS                              |                                              +                           |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       | +  +  +  +  M  +  +  +  +  +  +  +  M  +  +  +  M  +  M  +  M  +  +  M  +|             
      Inflammation, Acute                  |                      3                                                   |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Penis                                   |             +                                                            |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Suppurative            | 2     2                 1        2              2                        |             
      Duct, Cyst                           | 3  1  3           1  1  2  4  3  4  4  2  2  2  2  2  1  3  2        2  3|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
      Inflammation, Acute                  |                      3                                                   |             
      Inflammation, Chronic                |                                        1                    4            |             
      Inflammation, Chronic Active         |                                              1  4              4         |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hyperplasia                          |                                                 2                        |             
      Inflammation, Chronic                |                                                 2                        |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    1  3  1           2           3           2        4     2     1      |             
      Mineralization                       |       1                                                                  |             
      Artery, Inflammation                 | 2  4     3     4  2                                   3        2        3|             
      Artery, Mineralization               |                         2                                                |             
      Interstitial Cell, Hyperplasia       |                         2                                   2            |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  17                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Erythroid Cell, Hyperplasia          |                                              3                           |             
      Myeloid Cell, Hyperplasia            |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              | +  +  +  +     +  +  +  +  +  +  +  +     +  +  +  +  +  +  +  +  +  +  +|             
      Ectasia                              |                2                                                         |             
      Hemorrhage                           |                2                                                         |             
      Iliac, Ectasia                       | 2                                                           4            |             
      Iliac, Hemorrhage                    |                                                             4            |             
      Iliac, Hyperplasia, Lymphoid         |                                                                          |             
      Iliac, Hyperplasia, Plasma Cell      |                                                 4        2               |             
      Inguinal, Hemorrhage                 |                                                                         1|             
      Mediastinal, Atrophy                 |                                                                          |             
      Mediastinal, Congestion              |                         3                    4                           |             
      Mediastinal, Ectasia                 |                         1  3  1  1                 4  2              2   |             
      Mediastinal, Hemorrhage              |    4  3                    2              2  3        2  2  4        2   |             
      Mediastinal, Hyperplasia, Plasma Cell|                                           2           2                  |             
      Pancreatic, Ectasia                  |                                              3              4            |             
      Pancreatic, Hemorrhage               |                                              2              3            |             
      Pancreatic, Hyperplasia, Lymphoid    |                                                       4                  |             
      Renal, Ectasia                       | 3  4     3        3  3                       3              2            |             
      Renal, Fibrosis                      |                                                                          |             
      Renal, Hemorrhage                    | 2  3     2                                   2           3               |             
      Renal, Hyperplasia, Plasma Cell      |                                                          2               |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                            2              3                    2         |             
      Ectasia                              | 1              3                    2              4        2        2   |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                       3                  |             
      Hyperplasia, Plasma Cell             | 3                                4  3     3                              |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                      2                 2                       2         |             
      Ectasia                              |                                           2                             1|             
      Hemorrhage                           | 3  3  3                                      1           1  2        2  1|             
      Hyperplasia, Lymphoid                |                                                                          |             
      Hyperplasia, Plasma Cell             |                                           1                              |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |       4                                                                  |             
      Fibrosis                             |                                                                          |             
      Hematopoietic Cell Proliferation     |                                                                          |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 2  4  4     4        4     4        3  4     2  4        2  4  4         |             
      Cyst                                 |                   2        2                                             |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  18                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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               |                                                                          |             
                                           |                                                                          |             
      Ectopic Parathyroid Gland            |                                        2     2                           |             
      Hemorrhage                           |                   2                       1           1                  |             
      Artery, Mineralization               |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +|             
      Cyst                                 |          3                                                               |             
      Artery, Mineralization               |                         2              2                                 |             
      Duct, Dilatation                     |                      1        1                             2            |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                        2                                 |             
      Hyperplasia, Squamous                |                2                                                         |             
      Inflammation, Chronic                |                2                                                         |             
      Inflammation, Suppurative            |                                        2                                 |             
      Ulcer                                |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |    4  3  2  1  1        2              2                    4  2         |             
      Inflammation, Chronic Active         |                                                                          |             
      Cranium, Fibrous Osteodystrophy      |    4  2                 2              1                    4  3         |             
      Rib, Callus                          |                3                                                         |             
      Vertebra, Fibrous Osteodystrophy     |    3  2                                                                  |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Degeneration                         |                                                          1               |             
      Hemorrhage                           |                                     2                                    |             
      Hydrocephalus                        |                                                                          |             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |    +  +                                                                  |             
      Mineralization                       |    1  1                                                                  |             
      Radicular Neuropathy                 |    2  1                                                                  |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |    +  +                                                                  |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |          3  3                             3                              |             
      Edema                                |          2                                                     2         |             
      Hemorrhage                           |                                                                          |             
      Inflammation, Acute                  |                                                                          |             
      Inflammation, Granulomatous          |                2                                                         |             
      Mineralization                       |                                                                          |             
      Alveolar Epithelium, Hypertrophy     |                                                                          |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  19                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 6| 5| 6| 6| 7| 6| 4| 6| 5| 7| 7| 3| 6| 5| 6| 7| 7| 7| 5| 7| 6| 7| 7| 7|             
                             DAY ON TEST   | 4| 4| 4| 3| 9| 2| 3| 8| 5| 7| 2| 2| 7| 3| 9| 6| 1| 2| 2| 9| 1| 1| 2| 2| 2|             
                                           | 9| 2| 1| 9| 0| 2| 8| 6| 1| 3| 2| 2| 2| 4| 3| 0| 6| 2| 2| 5| 4| 1| 2| 2| 2|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
    100 PPM                                | 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                 |                                                                          |             
                                           |                                                                          |             
           Histiocyte                      |                                           1        1                     |             
      Artery, Mineralization               |                                                                          |             
      Interstitium, Fibrosis               |                                        1                    1            |             
      Interstitium, Inflammation, Chronic  |    2                    3                                                |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                X                                                         |             
      Inflammation, Acute                  |          3           1                          3           1  2         |             
      Inflammation, Chronic                |                1                                                         |             
      Inflammation, Chronic Active         |                                     3              3                     |             
      Metaplasia, Squamous                 |          2                                                               |             
      Respiratory Epithelium, Hyperplasia  |    2                                                        2     1      |             
      Respiratory Epithelium, Metaplasia   |                                                                          |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 | 2                                                                        |             
      Inflammation, Acute                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 | 3  4  1  3  3  3  1     4              4     2        2  2  2  4  4      |             
      Hydronephrosis                       |          1     2  2                          2  2                 2     2|             
      Inflammation, Acute                  |                                                 3              3         |             
      Mineralization                       |       1  2  2           3              1        3           3  3         |             
      Nephropathy                          | 4  4  4  4  4  4  4  4  4  4  3  2  3  4  3  4  4  2  4  4  4  4  4  3  3|             
      Artery, Mineralization               |          2                                                     2         |             
      Renal Tubule, Hyperplasia            |    2  4        2  2                    4                                 |             
      Vein, Thrombosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Edema                                |                                                                          |             
      Inflammation, Acute                  |                      1                                                   |             
      Ulcer                                |                                                 4                        |             
      Transitional Epithelium, Hyperplasia |                                                 2           4            |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  20                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +|  39        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  42        |
      Mineralization                       |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  A  +  +  +  +  A  +  A  +  +  +  +  +  +  +  +  +  +  A  A  +  +  +  +|  37        |
      Edema                                |                                  3                                       |      1  3.0|
      Hemorrhage                           |                                     2                                    |      2  2.0|
      Inflammation, Acute                  |                                                    4                     |      2  3.0|
      Ulcer                                |          3                                                               |      2  3.5|
      Artery, Mineralization               |                2                                                         |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  A  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  44        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  A  +  +  +  A  +  +  A  +  +  +  +  +  +  +  A  +  +  A  A  +  +  +  +|  36        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  A  +  +  +  A  A  +  A  +  +  +  +  +  +  +  +  +  +  A  A  +  A  A  +|  32        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                     2        2     2     2               |      9  1.8|
      Clear Cell Focus                     |                                                       X     X            |      7     |
      Congestion                           | 2                    3              2                       2        2   |     12  2.4|
      Degeneration, Cystic                 | 1        3           2     1                       2     1               |     13  1.4|
      Eosinophilic Focus                   | X                       X              X  X  X                 X         |     12     |
      Fibrosis                             |          2              2        1                                       |      5  1.4|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hepatodiaphragmatic Nodule           |                                                                          |      1     |
      Infiltration Cellular, Histiocyte    |                                                                          |      1  2.0|
      Inflammation, Acute                  |                                                                          |      1  1.0|
      Mineralization                       |          1                                                               |      1  1.0|
      Necrosis                             |                                                             1            |      7  1.7|
      Pigmentation                         |          2              1  1  1              2     1                    1|     15  1.3|
      Vacuolization Cytoplasmic            | 1                                      2  3  4  2  2     3  2  2         |     18  1.9|
      Artery, Mineralization               |                2                                                         |      1  2.0|
      Bile Duct, Dilatation                |                                  2                 2                     |      2  2.0|
      Bile Duct, Hyperplasia               | 1     2  1              1        1  1  4  2        1  1     1        2   |     33  1.4|
      Centrilobular, Cytomegaly            |                                                                1         |      1  1.0|
      Centrilobular, Degeneration          |    2  1        2        2  2     1              2                       2|     15  1.8|
      Centrilobular, Hypertrophy           |                                                    1                     |      1  1.0|
      Centrilobular, Necrosis              |          2                                               2        2      |      6  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   1        |
      Artery, Inflammation                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Oral Mucosa                             |                                        +                                 |   1        |
      Hyperplasia, Squamous                |                                        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  21                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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                  |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      3  1.3|
      Hemorrhage                           |                                                             2            |      1  2.0|
      Hyperplasia                          | 2  4     2        2                 4  2        4     2        3         |     18  2.8|
      Artery, Inflammation                 |                                                       4              4  2|      5  2.6|
      Artery, Mineralization               |                            2        2                    2               |      6  2.5|
      Duct, Hyperplasia                    |       2                                                                  |      1  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Inflammation, Acute                  |                   1                                                      |      1  1.0|
      Artery, Mineralization               |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia, Squamous                |                      1  2                          2           4        2|     13  2.4|
      Mineralization                       |                2           3        3                                    |      5  2.8|
      Ulcer                                |                                                                         2|      4  2.8|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Erosion                              |                               1                                          |      3  1.3|
      Fibrosis                             |                                                                          |      1  1.0|
      Mineralization                       |    3  3  3     4  3     2  4        4        1  2  1     3              3|     25  2.8|
      Serosa, Edema                        |                                  2                                       |      1  2.0|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                                           +                              |   2        |
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Granulomatous                   |                                           2                              |      1  2.0|
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Suppurative                     |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            |    +  +        +  +        +  +     +        +  +  +     +     +        +|  23        |
      Mineralization                       |    2           2                                         2              4|      6  2.5|
      Aorta, Mineralization                |       2        4  3        4        4        1  1  4     4     1        4|     21  2.8|
      Pulmonary Artery, Degeneration       |                               2                                          |      1  2.0|
      Pulmonary Artery, Mineralization     |                                                    3                     |      3  2.7|
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cardiomyopathy                       | 4  2  2  3     3  4  2  3  3  2  3  3  4  2  3  3  3  3  3  3  2  2  3  4|     49  2.7|
      Mineralization                       |    3  1  3     1           1        2           1  3     1              3|     17  1.8|
      Artery, Inflammation                 |                                                                          |      1  3.0|
      Artery, Mineralization               |    3     1     3  2        2        3           2  1     3               |     15  2.2|
      Atrium, Thrombosis                   |                                  3                                       |      2  2.5|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE 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  22                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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|            |
 __________________________________________________________________________________________________________________________________ 
 ENDOCRINE SYSTEM - cont                   |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      2  2.5|
      Degeneration                         |                                                                          |      2  2.0|
      Hyperplasia                          |                                                             2        3   |      2  2.5|
      Hypertrophy                          |                                                                          |      2  1.5|
      Mineralization                       |                                                                          |      1  2.0|
      Thrombosis                           |                         4                                                |      1  4.0|
      Vacuolization Cytoplasmic            | 1     1                             2     1           3  2     1     2   |     13  1.5|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                                  4           2                 3         |      4  3.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +|  47        |
      Hyperplasia                          |    4  4  4     4        4  4  1     4     2  3  4  4  4  4     3     4  4|     32  3.2|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 | 2           1                    2  3  1                             2   |     13  1.8|
      Hyperplasia                          |       2                       4        4                       3         |     10  3.0|
      Pars Distalis, Hyperplasia           |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      C-Cell, Hyperplasia                  |                                     3                                    |      1  3.0|
      Follicle, Cyst                       |                                              1                          1|      4  1.3|
      Follicular Cell, Hyperplasia         |                                                                          |      2  2.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Tissue NOS                              |                                                                          |   1        |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  M  +|  42        |
      Inflammation, Acute                  |                                                                          |      1  3.0|
      Artery, Mineralization               |                                                 2                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Penis                                   |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Chronic                |                      2                                      2            |      2  2.0|
      Inflammation, Suppurative            |                3           1        1                                   2|      9  1.8|
      Duct, Cyst                           | 1  1  3  2  1  3  2  2  2  2  2  2  3  3  3  2  2     2     2  3  4  3  3|     43  2.3|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |                      2        1        4  2                              |      4  2.3|
      Inflammation, Acute                  |                                                                          |      1  3.0|
 __________________________________________________________________________________________________________________________________ 

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

                                                             Page  23                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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|            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic                |                                  2                                1      |      4  2.0|
      Inflammation, Chronic Active         |                   4                 4                                    |      5  3.4|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 |                                                                      2   |      1  2.0|
      Hyperplasia                          |                                                                          |      1  2.0|
      Inflammation, Chronic                |                                                                          |      1  2.0|
      Artery, Mineralization               |                                                 2                        |      1  2.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |    2           2           1     3  4        3  3  2  1  3              3|     20  2.3|
      Mineralization                       |                                                 1                        |      2  1.0|
      Artery, Inflammation                 | 3                       3  1  2  1  3  1  4  2  2  1  4  3     3     3  3|     24  2.6|
      Artery, Mineralization               |          1                                                              2|      3  1.7|
      Interstitial Cell, Hyperplasia       | 2                                      2                                 |      4  2.0|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                    2                     |      1  2.0|
      Erythroid Cell, Hyperplasia          |                                                                          |      1  3.0|
      Myeloid Cell, Hyperplasia            |                                        2                                 |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              | +  +  +  +     +  +  +  +  +     +  +  +  +  +  +  +  +  +  +     +  +   |  44        |
      Ectasia                              |                                                                          |      1  2.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Iliac, Ectasia                       |                                        2                                 |      3  2.7|
      Iliac, Hemorrhage                    |                                        2                                 |      2  3.0|
      Iliac, Hyperplasia, Lymphoid         |                                                                   3      |      1  3.0|
      Iliac, Hyperplasia, Plasma Cell      |                   2                 3                                    |      4  2.8|
      Inguinal, Hemorrhage                 |                                                                          |      1  1.0|
      Mediastinal, Atrophy                 |                3                                                         |      1  3.0|
      Mediastinal, Congestion              |                                                                   4      |      3  3.7|
      Mediastinal, Ectasia                 | 2                    1           3     2  2                              |     12  2.0|
      Mediastinal, Hemorrhage              |          1                       3        2        3     2        1      |     15  2.4|
      Mediastinal, Hyperplasia, Plasma Cell|                                                                          |      2  2.0|
      Pancreatic, Ectasia                  |                2                 4                    4                  |      5  3.4|
      Pancreatic, Hemorrhage               |                            2     2                 2                     |      5  2.2|
      Pancreatic, Hyperplasia, Lymphoid    |                                                                          |      1  4.0|
      Renal, Ectasia                       |          4     4  3     4  4     4  3  3     3  3  3     3           4   |     20  3.3|
      Renal, Fibrosis                      |                            2     2                                       |      2  2.0|
      Renal, Hemorrhage                    |          2     2  3     2  4     3  3  2     2  3  3     3               |     17  2.6|
      Renal, Hyperplasia, Plasma Cell      |                                                                          |      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  24                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Congestion                           |       3                                         3                        |      5  2.6|
      Ectasia                              |                                           2           2                  |      8  2.3|
      Hemorrhage                           |                                                                      1   |      1  1.0|
      Hyperplasia, Lymphoid                |                                                                          |      1  3.0|
      Hyperplasia, Plasma Cell             | 2                                   2  2                             4   |      8  2.9|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |    3                             2                                      4|      6  2.5|
      Ectasia                              |                2                 2           2              3            |      6  2.0|
      Hemorrhage                           |    2     1                 3     1                 2                    2|     14  1.9|
      Hyperplasia, Lymphoid                |                                                                2         |      1  2.0|
      Hyperplasia, Plasma Cell             |       2                                                                  |      2  1.5|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  4.0|
      Fibrosis                             |                                  2                                       |      1  2.0|
      Hematopoietic Cell Proliferation     |                         3                                         3      |      2  3.0|
      Artery, Mineralization               |                                                          1               |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |    4  3        4  3     3  4  1  4  4        2  3  4     4     1     1  4|     29  3.2|
      Cyst                                 |          2     2              1                                   1      |      6  1.7|
      Ectopic Parathyroid Gland            |                2        2  2                                             |      5  2.0|
      Hemorrhage                           |                      1  2              2                                 |      6  1.5|
      Artery, Mineralization               |                                                          4               |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +|  46        |
      Cyst                                 |                                                                         3|      2  3.0|
      Artery, Mineralization               |       2        2           2                                             |      5  2.0|
      Duct, Dilatation                     |                               2           1  2  1                        |      7  1.4|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                         2|      2  2.0|
      Hyperplasia, Squamous                |                      3                                                   |      2  2.5|
      Inflammation, Chronic                |                      2                                                   |      2  2.0|
      Inflammation, Suppurative            |                                                                          |      1  2.0|
      Ulcer                                |                                                                   3      |      1  3.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               |    2  2  3     4  3     3  2        4           4  3     4              3|     21  2.8|
 __________________________________________________________________________________________________________________________________ 

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

                                                             Page  25                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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|            |
 __________________________________________________________________________________________________________________________________ 
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic Active         |                                                    4                     |      1  4.0|
      Cranium, Fibrous Osteodystrophy      |       1  3     2  1        1        4           4  2     1               |     15  2.3|
      Rib, Callus                          |                                                                          |      1  3.0|
      Vertebra, Fibrous Osteodystrophy     |                                                    1                    1|      4  1.8|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Degeneration                         |                                                                          |      1  1.0|
      Hemorrhage                           |                                                                          |      1  2.0|
      Hydrocephalus                        |                                              2                           |      1  2.0|
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                    +                    +|   4        |
      Mineralization                       |                                                                          |      2  1.0|
      Radicular Neuropathy                 |                                                    1                    1|      4  1.3|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                    +                    +|   4        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                 2                        |      4  2.8|
      Edema                                |                                                                          |      2  2.0|
      Hemorrhage                           |                                                                      1   |      1  1.0|
      Inflammation, Acute                  |                                     3           1                    2   |      3  2.0|
      Inflammation, Granulomatous          |                                                                          |      1  2.0|
      Mineralization                       |                   2                                                      |      1  2.0|
      Alveolar Epithelium, Hypertrophy     |                1                                                         |      1  1.0|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                  2              2        3               |      5  1.8|
      Artery, Mineralization               |       3  1     1                                                         |      3  1.7|
      Interstitium, Fibrosis               |                1  3              2                       2               |      6  1.7|
      Interstitium, Inflammation, Chronic  |                                                                          |      2  2.5|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |             X                 X                                      X   |      4     |
      Inflammation, Acute                  |                   1                                                  4   |      7  2.1|
      Inflammation, Chronic                |                                                                          |      1  1.0|
      Inflammation, Chronic Active         |             3                 1     3              1                     |      6  2.3|
      Metaplasia, Squamous                 |                                                                          |      1  2.0|
      Respiratory Epithelium, Hyperplasia  |             3              1  1  2  2              2                     |      9  1.8|
      Respiratory Epithelium, Metaplasia   |             1                                                            |      1  1.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      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  26                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 4| 5| 5| 3| 4| 3| 7| 6| 6| 7| 6| 5| 7| 7| 6| 5| 6| 7| 6| 4| 7| 5| 6| 5|            |
                             DAY ON TEST   | 2| 4| 3| 8| 3| 7| 5| 1| 8| 1| 2| 9| 6| 2| 2| 6| 4| 7| 2| 9| 7| 2| 5| 4| 0|            |
                                           | 2| 5| 6| 1| 6| 9| 2| 0| 2| 0| 2| 8| 1| 2| 2| 8| 9| 9| 2| 7| 0| 2| 2| 7| 6|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    100 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                 |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Acute                  |                                     4                                    |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 | 1  2  2  3     2           3  2  3  2        2     3  3  2     3     1  2|     31  2.5|
      Hydronephrosis                       | 1           3        2  2        1  1  2  2  1           2  2  1     2   |     20  1.8|
      Inflammation, Acute                  |                                                                          |      2  3.0|
      Mineralization                       |       1        2  3        2        2           1  2     2              2|     17  2.1|
      Nephropathy                          | 3  4  4  4  2  4  4  2  4  4  4  3  4  4  3  4  4  4  4  4  1  4  1  4  4|     50  3.6|
      Artery, Mineralization               |                3           1                    2        3     1        1|      8  1.9|
      Renal Tubule, Hyperplasia            |    2     2     1           2  1  2  1        3     2  1              1  3|     17  2.1|
      Vein, Thrombosis                     |                                  2           2                           |      2  2.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Edema                                |                                     2                                    |      1  2.0|
      Inflammation, Acute                  |                                                                          |      1  1.0|
      Ulcer                                |                                                                          |      1  4.0|
      Transitional Epithelium, Hyperplasia |                   2                                                      |      3  2.7|
 __________________________________________________________________________________________________________________________________ 

  * : 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  27                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | A  +  A  +  +  A  A  +  +  +  A  +  +  +  A  +  +  A  +  +  +  +  A  A  +|             
      Mineralization                       |                                                             2            |             
      Parasite Metazoan                    |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | A  +  A  +  +  A  A  +  +  +  A  +  +  +  +  +  +  A  +  +  +  +  A  +  +|             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  +  A  +  +  A  A  +  +  +  A  +  +  +  A  +  +  A  +  A  +  +  A  A  +|             
      Congestion                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation, Acute                  |                                                             4            |             
      Inflammation, Chronic                |                                  2                                       |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | +  +  A  +  +  A  A  +  +  +  A  A  +  +  A  +  +  +  +  +  +  +  A  A  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  +  A  +  +  A  A  +  +  +  A  A  +  +  A  +  +  A  +  A  +  +  A  A  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          | 3                                   3                                    |             
      Clear Cell Focus                     |    X     X                 X                 X  X                        |             
      Congestion                           | 3              4              2              3                           |             
      Degeneration, Cystic                 |                               2           1              2     1         |             
      Eosinophilic Focus                   |    X                          X                                          |             
      Fibrosis                             | 1     2     1  1  1  1     1  2  1  1     2        2     2  3        2  1|             
      Hemorrhage                           |                                                          2     1         |             
      Hepatodiaphragmatic Nodule           |       X                                                                  |             
      Hypertrophy                          |                                           2                              |             
      Infarct                              |                                                                          |             
      Infiltration Cellular, Histiocyte    |                                                                          |             
      Inflammation, Acute                  |                                        2                    2     2      |             
      Mineralization                       |                                                                          |             
      Mixed Cell Focus                     |                                     X                                    |             
      Necrosis                             |                                                                          |             
      Pigmentation                         | 1        2  3  1  2  1        2  1  3  2  3        3     2  1  1  1  2  2|             
      Tension Lipidosis                    |             X                                                            |             
      Thrombosis                           |                                                                          |             
      Vacuolization Cytoplasmic            | 1     2  2                       2        1     2        1     4         |             
      Bile Duct, Cyst                      |                                                                          |             
      Bile Duct, Hyperplasia               | 3  2  1  3     1        1  1  1     2  3        1  4  1  3     1     1  1|             
      Centrilobular, Cytomegaly            |                                                                3         |             
      Centrilobular, Degeneration          |    1  3     1     2  4        1  3           1        3     3     3  1  1|             
      Centrilobular, Necrosis              |                   2                                      2               |             
      Hepatocyte, Atrophy                  |    2                                                                     |             
      Periportal, Fibrosis                 | 2                                         2        2                     |             
                                            __________________________________________________________________________|             
   Mesentery                               |          +              +                                                |             
      Vein, Thrombosis                     |          4              2                                                |             
                                            __________________________________________________________________________|             
   Oral Mucosa                             |                               +                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  28                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 ALIMENTARY SYSTEM - cont                  |                                                                          |             
                                           |                                                                          |             
      Hyperplasia, Squamous                |                               3                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |          2                                                               |             
      Edema                                |                                                                          |             
      Fibrosis                             |          2                                                               |             
      Hyperplasia                          |          4                 2                    4     3              3   |             
      Acinus, Hyperplasia                  |                                  3                                       |             
      Artery, Inflammation                 |                                                                          |             
      Artery, Mineralization               |                                                                          |             
      Duct, Hyperplasia                    |                                                                          |             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Duct, Cyst                           |                                                                          |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                         2                                                |             
      Foreign Body                         |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Squamous                |                                  4  3  2  1     1              3        4|             
      Inflammation, Chronic                |                                                                          |             
      Mineralization                       |                                                                          |             
      Ulcer                                |                                        2  2                    3         |             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Erosion                              |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Inflammation, Chronic Active         |                                                    2                     |             
      Mineralization                       |                   4  2           4  3     1           3              1   |             
      Ulcer                                |                                                                4         |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Tongue                                  |                                                                          |             
                                            __________________________________________________________________________|             
   Tooth                                   |                +                    +                                   +|             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Suppurative                     |                4                    3                                   3|             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            |                   +              +  +     +           +     +     +      |             
      Mineralization                       |                                                                          |             
      Aorta, Mineralization                |                   3              4  2     1           3     2            |             
      Pulmonary Artery, Mineralization     |                                  3                    3     1     1      |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  2  3  4  3  4  4  3  2  2  3  4  2  2  3  1  2  3  2  1  3  2  3  3  2|             
      Mineralization                       |                   3  1           1        3                 2            |             
      Thrombosis                           |                                                                          |             
      Artery, Mineralization               |                   3              3                          2        2   |             
      Atrium, Dilatation                   |                                                          4               |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  29                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 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              |                                                                          |             
                                           |                                                                          |             
      Atrium, Thrombosis                   |             1     2                                      1        2      |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                             1            |             
      Hyperplasia                          |                                                                          |             
      Hypertrophy                          |                2                                                         |             
      Vacuolization Cytoplasmic            | 2        2                    1        1                       2        1|             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                          2               |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                                                                3         |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          | 2           2  2  4  2           4  1     4           4  4  4  2  4  2  1|             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 | 1     2              2           2  1     2  3           2  1     3      |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          | 4  4                       4                    2                        |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Granulomatous          |                                                 2                        |             
      C-Cell, Hyperplasia                  |                                                                          |             
      Follicle, Cyst                       |    2     3  4                 2                                          |             
      Follicular Cell, Hyperplasia         |                                  4                                       |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       | M  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Acute                  |                                                                         4|             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                          2               |             
      Inflammation, Chronic                |                                     2           3  1                     |             
      Inflammation, Chronic Active         |                                                                          |             
      Inflammation, Suppurative            |    2                                                  3     4  4         |             
      Duct, Cyst                           | 1  3  2  2     3  2  2  2  1  2  1  2  2  2     2  2  2  1  2  3  3  3  1|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                     1                       2            |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Inflammation, Chronic                |                2           2                             1              4|             
      Inflammation, Chronic Active         |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  30                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 PPM                                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 2| 2| 2| 2| 2| 2|             
                                           | 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5| 6| 7| 8| 9| 0| 1| 2| 3| 4| 5|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Inflammation, Chronic Active         |                                                                         2|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |    2              4  4           2        1        3  1  2  2  4  1      |             
      Inflammation, Granulomatous          |                                                                          |             
      Mineralization                       |                                                    1  1  1        1  1   |             
      Artery, Inflammation                 |          2     2              2           1  1              2  3         |             
      Artery, Mineralization               |                   1                       3                              |             
      Interstitial Cell, Hyperplasia       | 2  4     2                                      2                    2   |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Myeloid Cell, Hyperplasia            |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node                              |    +  +  +  +  +  +  +        +     +        +  +  +  +     +  +  +  +  +|             
      Iliac, Ectasia                       |                                                             2           4|             
      Iliac, Hemorrhage                    |                                                                   3      |             
      Iliac, Hyperplasia, Lymphoid         |                                                             2            |             
      Iliac, Hyperplasia, Plasma Cell      |                                                                         3|             
      Inguinal, Ectasia                    |                                                                      2   |             
      Inguinal, Hemorrhage                 |                                                                          |             
      Inguinal, Hyperplasia, Lymphoid      |                                                       2                  |             
      Inguinal, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                                                                          |             
      Mediastinal, Congestion              |       3                                                                  |             
      Mediastinal, Ectasia                 |    1  2     2     2  2                                2     1     1     1|             
      Mediastinal, Hemorrhage              |                   2  3                                2     1     3      |             
      Mediastinal, Hyperplasia, Plasma Cell|             2                                                            |             
      Pancreatic, Hemorrhage               |          2                                                        2     1|             
      Pancreatic, Hyperplasia, Plasma Cell |          2                                                               |             
      Pancreatic, Pigmentation             |          2                                                               |             
      Renal, Ectasia                       |             4  2  3  3        2     2        3        2     4           1|             
      Renal, Hemorrhage                    |          2     2  3  3        1     2        1     2  3     2     3      |             
      Renal, Hyperplasia, Lymphoid         |                                                                          |             
      Renal, Hyperplasia, Plasma Cell      |          3                                   2     2                    2|             
      Renal, Pigmentation                  |          2  2  2                                                         |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                                                          |             
      Ectasia                              |                4        4              1                 2  2            |             
      Hemorrhage                           |                                                                   1      |             
      Hyperplasia, Plasma Cell             | 3              3                                   2              2      |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Ectasia                              |                                           1  1  2        2  2            |             
      Hemorrhage                           |          3           3  3        2        2  1     1              1      |             
      Hyperplasia, Lymphoid                |                                                    4                     |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  31                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 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               |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Atrophy                              |                                  2                                       |             
      Congestion                           |                                                                          |             
      Fibrosis                             |                                                                          |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |             2     4  4  2        4  3  2  4           3  4  4  1  2  2   |             
      Cyst                                 |                                                 2                        |             
      Ectopic Parathyroid Gland            |                               2                                          |             
      Fibrosis                             |                                                                      4   |             
      Hemorrhage                           |       2                                2           3                     |             
      Epithelial Cell, Hyperplasia         |             4                                                            |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  M  +  M  +  +  +  +  +|             
      Hyperplasia                          |                                                 2                        |             
      Duct, Dilatation                     |                1     1                                         1         |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                                                    2                     |             
      Hyperplasia, Squamous                |                                                                      2   |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |                   3  2           3  4     3           3     4     1      |             
      Osteosclerosis                       |                                                                          |             
      Cranium, Fibrous Osteodystrophy      |                   3  2           3  2     3           2     3            |             
      Joint, Inflammation, Chronic         | 3                                                                        |             
      Metatarsal, Hyperplasia              |                                                                          |             
      Vertebra, Fibrous Osteodystrophy     |                                                       2     2            |             
                                            __________________________________________________________________________|             
   Skeletal Muscle                         |                                                                         +|             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                                                       +     +            |             
      Mineralization                       |                                                       1     1            |             
      Radicular Neuropathy                 |                                                             2            |             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                                                       +     +            |             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                                        2                             3   |             
      Hemorrhage                           |                   1                                                      |             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Granulomatous          |          1  2                                         1                 1|             
      Necrosis                             |                                                                          |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  32                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 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                 |                                                                          |             
                                           |                                                                          |             
      Alveolar Epithelium, Hyperplasia     |          3                    2                                          |             
      Alveolus, Infiltration Cellular,     |                                                                          |             
           Histiocyte                      |                   3                                                     2|             
      Interstitium, Fibrosis               |                                                          1               |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                     X                                    |             
      Hemorrhage                           |       1                                                                  |             
      Inflammation, Acute                  |                   1                                                      |             
      Inflammation, Chronic                |                               3                                          |             
      Inflammation, Chronic Active         |                                     3        2              3            |             
      Metaplasia, Squamous                 |                                                             2            |             
      Thrombosis                           |                                                                          |             
      Ulcer                                |                                                                          |             
      Olfactory Epithelium, Metaplasia     |                                                                          |             
      Respiratory Epithelium, Hyperplasia  |          1        1        2              1        1     1     1         |             
      Respiratory Epithelium, Metaplasia,  |                                                                          |             
           Squamous                        |                2                                                         |             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                                          |             
                                            __________________________________________________________________________|             
   Eye                                     |                                                                          |             
      Cornea, Ulcer                        |                                                                          |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                     +                 +                  |             
                                            __________________________________________________________________________|             
   Lacrimal Gland                          |                                                                          |             
      Atrophy                              |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                         +                                                |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |    2     3  4        2     1  2  1  2     3              3  4        2   |             
      Hydronephrosis                       |          3     2  1     3     2  2  2  3  1     1  1  1  2  2     2      |             
      Mineralization                       |                                  2     1              1  2               |             
      Nephropathy                          | 3  3  3  4  4  4  4  4  2  3  3  4  4  3  4  3  3  4  4  4  4  3  4  4  3|             
      Artery, Mineralization               |                                  3                                       |             
      Renal Tubule, Accumulation, Hyaline  |                                                                          |             
          Droplet                          |                                                                          |             
      Renal Tubule, Hyperplasia            |             3              3        2     2           2     3            |             
      Vein, Thrombosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  A  +  +|             
      Dilatation                           |                                                                          |             
      Hemorrhage                           |                                                                          |             
      Inflammation, Chronic Active         |                                                                         1|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  33                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 6| 7| 4| 7| 7| 6| 4| 5| 6| 7| 7| 6| 3| 4| 6| 7| 7| 6| 5| 6| 7| 7| 6| 5| 7|             
                             DAY ON TEST   | 5| 2| 8| 2| 2| 3| 8| 2| 8| 2| 0| 2| 5| 0| 0| 2| 2| 7| 0| 8| 2| 0| 2| 4| 2|             
                                           | 0| 2| 7| 2| 2| 2| 6| 0| 3| 2| 0| 8| 4| 4| 8| 2| 2| 4| 1| 2| 1| 4| 2| 8| 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|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    200 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                     |                                                                          |             
                                           |                                                                          |             
      Artery, Mineralization               |                                                                          |             
      Transitional Epithelium, Hyperplasia |                                                                         3|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  34                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |                                                                X         |      1     |
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  +  +  +  +  A  +  +  +  +  +  A  +  +  +  A  +  A  +  +  A  +  +  +  +|  36        |
      Mineralization                       |                                                                          |      1  2.0|
      Parasite Metazoan                    |                                                 X                        |      1     |
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +|  41        |
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | +  +  +  +  +  A  +  +  M  +  A  A  A  +  +  A  A  A  +  +  A  +  A  +  A|  29        |
      Congestion                           |                      3                                                   |      1  3.0|
      Hemorrhage                           |                      1                                                   |      1  1.0|
      Inflammation, Acute                  |                                                                      2   |      2  3.0|
      Inflammation, Chronic                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  +  +  +  +  +  A  A  A  +  +  +  +  A  +  +  A  +  +  +  +|  42        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  +  +  +  +  +  +  A  +  +  A  A  A  +  +  +  A  A  +  +  A  +  A  +  +|  34        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  +  +  A  +  A  +  A  +  +  A  A  +  +  +  +  A  A  +  A  A  +  A  +  A|  28        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                                                          |      2  3.0|
      Clear Cell Focus                     | X                       X                 X                              |      8     |
      Congestion                           |                                              3              3            |      6  3.0|
      Degeneration, Cystic                 |    1                 1  1  1           1                                 |      9  1.2|
      Eosinophilic Focus                   |                                           X                 X            |      4     |
      Fibrosis                             |    1                 1        1  3        1  3  2        2        1  2   |     26  1.6|
      Hemorrhage                           |          3              2        2                                       |      5  2.0|
      Hepatodiaphragmatic Nodule           |                                                                   X      |      2     |
      Hypertrophy                          |                                                                          |      1  2.0|
      Infarct                              |          3                                                               |      1  3.0|
      Infiltration Cellular, Histiocyte    |                                  2                       3               |      2  2.5|
      Inflammation, Acute                  |                                                                          |      3  2.0|
      Mineralization                       |                                                          2           1  1|      3  1.3|
      Mixed Cell Focus                     |                                                                          |      1     |
      Necrosis                             |    1     2        1              2                    2  2               |      6  1.7|
      Pigmentation                         | 2  2           1  1  2     3     2     1  2  2  3  1     1     1  2  3   |     34  1.8|
      Tension Lipidosis                    |                                                                          |      1     |
      Thrombosis                           |          2                                                               |      1  2.0|
      Vacuolization Cytoplasmic            |                         1                       3           1        2   |     12  1.8|
      Bile Duct, Cyst                      | 4                                                                       3|      2  3.5|
      Bile Duct, Hyperplasia               | 1     1              1  1     3  2     1  1  4  3           2     2  1   |     30  1.8|
      Centrilobular, Cytomegaly            |                                                                          |      1  3.0|
      Centrilobular, Degeneration          | 2  1        4  3     3           2        2  1     2  1  1        3      |     25  2.1|
      Centrilobular, Necrosis              |                                                       3                 4|      4  2.8|
 __________________________________________________________________________________________________________________________________ 

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

                                                             Page  35                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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                  |                                                                          |            |
                                           |                                                                          |            |
      Hepatocyte, Atrophy                  |                                                                          |      1  2.0|
      Periportal, Fibrosis                 |                                              2                       2   |      5  2.0|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                                                          |   2        |
      Vein, Thrombosis                     |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Oral Mucosa                             |                                                                          |   1        |
      Hyperplasia, Squamous                |                                                                          |      1  3.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                              2           2               |      3  2.0|
      Edema                                |                                                       2                  |      1  2.0|
      Fibrosis                             |                                                                          |      1  2.0|
      Hyperplasia                          |                         3              4                                2|      8  3.1|
      Acinus, Hyperplasia                  |                                                                          |      1  3.0|
      Artery, Inflammation                 |                                                    3     3        3      |      3  3.0|
      Artery, Mineralization               |                                                    4                     |      1  4.0|
      Duct, Hyperplasia                    |                                              2                           |      1  2.0|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  +  +  +  +  M  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Duct, Cyst                           |                                                          1               |      1  1.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      1  2.0|
      Foreign Body                         |                                                                X         |      1     |
      Hemorrhage                           |       1                                                                  |      1  1.0|
      Hyperplasia, Squamous                |       2  2                                               1     2         |     11  2.3|
      Inflammation, Chronic                |                                                          1               |      1  1.0|
      Mineralization                       |             4                                      4              4      |      3  4.0|
      Ulcer                                |                                                                          |      3  2.3|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Erosion                              |       1  4                                                               |      2  2.5|
      Hemorrhage                           |                            1                                            4|      2  2.5|
      Hyperplasia                          |                                  2                                       |      1  2.0|
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
      Mineralization                       |             4  3     2     2  2  1                 4              2  2   |     16  2.5|
      Ulcer                                |                                                                          |      1  4.0|
      Artery, Mineralization               |                                                    3                     |      1  3.0|
                                            __________________________________________________________________________|____________|
   Tongue                                  |                            +                                             |   1        |
                                            __________________________________________________________________________|____________|
   Tooth                                   |                            +                                             |   4        |
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Suppurative                     |                            3                                             |      4  3.3|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR 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  36                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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              |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            |             +  +                                   +     +        +      |  12        |
      Mineralization                       |             4                                                            |      1  4.0|
      Aorta, Mineralization                |             4  4                                   4              3      |     10  3.0|
      Pulmonary Artery, Mineralization     |                                                          2               |      5  2.0|
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cardiomyopathy                       | 2  1  3  2  3  3     3  3  2  3  4  3  3  3  3  3  4  3  3  3  3  4  3  2|     49  2.7|
      Mineralization                       |             1  3     2                             1     2     2  3      |     12  2.0|
      Thrombosis                           |       1                                                                  |      1  1.0|
      Artery, Mineralization               |             3              3                       3     2     2         |      9  2.6|
      Atrium, Dilatation                   |                                                                          |      1  4.0|
      Atrium, Thrombosis                   |                                                 4                        |      5  2.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                                                          |      1  1.0|
      Hyperplasia                          |                                     3                                    |      1  3.0|
      Hypertrophy                          | 2                                                                        |      2  2.0|
      Vacuolization Cytoplasmic            | 1     1                    3              1        2                    1|     12  1.5|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                         3                                                |      2  2.5|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |                            3                                             |      2  3.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Hyperplasia                          |       4     4  4     4     2                 2  4  4     3  3  2  4  2  2|     29  3.0|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |             3  3        2  2              1  1           1     2         |     18  1.9|
      Hemorrhage                           |       1                                                                  |      1  1.0|
      Hyperplasia                          | 3                    3                                         4         |      7  3.4|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Inflammation, Granulomatous          |                                                                          |      1  2.0|
      C-Cell, Hyperplasia                  | 2                                                                        |      1  2.0|
      Follicle, Cyst                       |                            3                                             |      5  2.8|
      Follicular Cell, Hyperplasia         |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       | +  +  M  +  +  +  +  +  +  M  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +|  45        |
 __________________________________________________________________________________________________________________________________ 

  * : 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: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Acute                  |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  2.0|
      Inflammation, Chronic                |                                                                          |      3  2.0|
      Inflammation, Chronic Active         |    4                                                                     |      1  4.0|
      Inflammation, Suppurative            |    2                       3     3                          3     2  2   |     10  2.8|
      Duct, Cyst                           | 2     4  3  4  3  2  3     2  2  3  4  2  2  3  2  2  2  3  3  3  2  3  2|     46  2.3|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrosis                             |                                                                          |      2  1.5|
      Hemorrhage                           |                               3                                          |      1  3.0|
      Hyperplasia                          | 3                                                                        |      1  3.0|
      Inflammation, Chronic                |                                        1                                 |      5  2.0|
      Inflammation, Chronic Active         |                            3     1                                       |      2  2.0|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +|  49        |
      Atrophy                              |    3  3     3  2     3  4                                   4            |     18  2.7|
      Inflammation, Granulomatous          |                         3                                                |      1  3.0|
      Mineralization                       |             2     1           1                    2                     |      9  1.2|
      Artery, Inflammation                 | 3                    2                    2  3  2                 3     2|     14  2.1|
      Artery, Mineralization               |                                                                          |      2  2.0|
      Interstitial Cell, Hyperplasia       |                            2  2                                          |      7  2.3|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Myeloid Cell, Hyperplasia            |                   3                                                      |      1  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              |    +  +  +  +  +  +  +        +  +  +  +  +  +  +  +     +  +  +  +     +|  38        |
      Iliac, Ectasia                       |                               3                                          |      3  3.0|
      Iliac, Hemorrhage                    |                               2                                          |      2  2.5|
      Iliac, Hyperplasia, Lymphoid         |                                     2                                    |      2  2.0|
      Iliac, Hyperplasia, Plasma Cell      |    3                                                                     |      2  3.0|
      Inguinal, Ectasia                    |                                                                          |      1  2.0|
      Inguinal, Hemorrhage                 |                                                          2               |      1  2.0|
      Inguinal, Hyperplasia, Lymphoid      |                                                                          |      1  2.0|
      Inguinal, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                                          2               |      1  2.0|
      Mediastinal, Congestion              |                                  3                                       |      2  3.0|
      Mediastinal, Ectasia                 |                                                                          |      9  1.6|
 __________________________________________________________________________________________________________________________________ 

  * : 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: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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               |                                                                          |            |
                                           |                                                                          |            |
      Mediastinal, Hemorrhage              |             3                    2     1           3     2               |     10  2.2|
      Mediastinal, Hyperplasia, Plasma Cell|                                                                          |      1  2.0|
      Pancreatic, Hemorrhage               |                               2                                          |      4  1.8|
      Pancreatic, Hyperplasia, Plasma Cell |                                                          2               |      2  2.0|
      Pancreatic, Pigmentation             |                                                                          |      1  2.0|
      Renal, Ectasia                       |                   2  3        2           2     2                 4      |     16  2.6|
      Renal, Hemorrhage                    |                   1           1     2     2     2        2        4     3|     19  2.2|
      Renal, Hyperplasia, Lymphoid         |                                     2                                    |      1  2.0|
      Renal, Hyperplasia, Plasma Cell      |    3                                                     3               |      6  2.5|
      Renal, Pigmentation                  |                                                                          |      3  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  +  +  +  +  M  +  +  +  +  +  M  M  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Congestion                           |          3                                                               |      1  3.0|
      Ectasia                              | 2        2                                         2                 2  3|     10  2.4|
      Hemorrhage                           |       2              2                                                   |      3  1.7|
      Hyperplasia, Plasma Cell             |                   4                                                     4|      6  3.0|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |             2                                                            |      1  2.0|
      Ectasia                              |    1                                                                     |      6  1.5|
      Hemorrhage                           |    1                 2           1                       2               |     12  1.8|
      Hyperplasia, Lymphoid                |    3                                                                     |      2  3.5|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |                                                                          |      1  2.0|
      Congestion                           |          2                                                               |      1  2.0|
      Fibrosis                             |       3                                                                  |      1  3.0|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |          2  4  4  4  3     3  4  3              4  3     1     3  4  3   |     28  3.1|
      Cyst                                 |                   2           2                       1                  |      4  1.8|
      Ectopic Parathyroid Gland            |                                                                          |      1  2.0|
      Fibrosis                             |                                                                          |      1  4.0|
      Hemorrhage                           |          2                       2  1                 1                 1|      8  1.8|
      Epithelial Cell, Hyperplasia         |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +|  44        |
      Hyperplasia                          |                   3                                                      |      2  2.5|
      Duct, Dilatation                     |       2                                            2                     |      5  1.4|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |                                                                          |      1  2.0|
      Hyperplasia, Squamous                |                                                                          |      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  39                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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|            |
 __________________________________________________________________________________________________________________________________ 
 INTEGUMENTARY SYSTEM - cont               |                                                                          |            |
                                           |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               |             3  2     3           3              3  3              4  2   |     16  2.9|
      Osteosclerosis                       |                                                    2                     |      1  2.0|
      Cranium, Fibrous Osteodystrophy      |             4        1           3              3  4              4      |     13  2.8|
      Joint, Inflammation, Chronic         |                                                                          |      1  3.0|
      Metatarsal, Hyperplasia              |                                                 4                        |      1  4.0|
      Vertebra, Fibrous Osteodystrophy     |                                                                          |      2  2.0|
                                            __________________________________________________________________________|____________|
   Skeletal Muscle                         |                                                                         +|   2        |
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                                          |   2        |
      Mineralization                       |                                                                          |      2  1.0|
      Radicular Neuropathy                 |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                                          |   2        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      2  2.5|
      Hemorrhage                           |       2        1                    1  1              1     1     2  1  1|     10  1.2|
      Inflammation, Chronic                |    1                                                                     |      1  1.0|
      Inflammation, Granulomatous          |                            1                                             |      5  1.2|
      Necrosis                             |                                                       1                  |      1  1.0|
      Alveolar Epithelium, Hyperplasia     |                                                                          |      2  2.5|
      Alveolus, Infiltration Cellular,     |                                                                          |            |
           Histiocyte                      |                                                 2  2                     |      4  2.3|
      Interstitium, Fibrosis               |                                                 2  2              1      |      4  1.5|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |          X     X  X                                            X     X   |      6     |
      Hemorrhage                           |                                                                          |      1  1.0|
      Inflammation, Acute                  |                                                                3     4  1|      4  2.3|
      Inflammation, Chronic                |                         1                                                |      2  2.0|
      Inflammation, Chronic Active         |          4     1                                                         |      5  2.6|
      Metaplasia, Squamous                 |                                                                          |      1  2.0|
      Thrombosis                           |       3                                                                  |      1  3.0|
      Ulcer                                |                   2                                            1         |      2  1.5|
      Olfactory Epithelium, Metaplasia     |                                                                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  40                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 7| 5| 7| 4| 5| 5| 4| 5| 7| 7| 7| 5| 5| 7| 7| 6| 6| 6| 4| 6| 6| 4| 6| 4| 6|            |
                             DAY ON TEST   | 2| 1| 1| 4| 0| 1| 9| 7| 2| 0| 0| 6| 8| 2| 2| 6| 8| 7| 8| 3| 3| 7| 6| 7| 4|            |
                                           | 2| 5| 3| 7| 0| 0| 4| 5| 2| 4| 5| 1| 8| 2| 2| 0| 8| 5| 1| 0| 1| 9| 4| 3| 5|      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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    200 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                 |                                                                          |            |
                                           |                                                                          |            |
      Respiratory Epithelium, Hyperplasia  |    2        2                                1     3     1               |     12  1.4|
      Respiratory Epithelium, Metaplasia,  |                                                                          |            |
           Squamous                        |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |             X                                                            |      1     |
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |    +                                                                     |   1        |
                                            __________________________________________________________________________|____________|
   Eye                                     |                   +                                                      |   1        |
      Cornea, Ulcer                        |                   4                                                      |      1  4.0|
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                        +                                +|   4        |
                                            __________________________________________________________________________|____________|
   Lacrimal Gland                          |                   +                                                      |   1        |
      Atrophy                              |                   2                                                      |      1  2.0|
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                   +                                                      |   2        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cyst                                 |             3  2     3           3     2  2                       4      |     19  2.5|
      Hydronephrosis                       | 1  1        2  2  1  1        3  2           1  2  2        2  2     1  1|     30  1.7|
      Mineralization                       |             3              2                       2           2         |      8  1.9|
      Nephropathy                          | 4  3  1  2  4  4  4  4  2  3  4  4  2  3  4  4  4  4  2  4  2  2  4  4  4|     50  3.4|
      Artery, Mineralization               |             3                                      2                     |      3  2.7|
      Renal Tubule, Accumulation, Hyaline  |                                                                          |            |
          Droplet                          |                   3                                                      |      1  3.0|
      Renal Tubule, Hyperplasia            |                   2                       2                              |      8  2.4|
      Vein, Thrombosis                     |                                  2                                       |      1  2.0|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Dilatation                           |                               2                                          |      1  2.0|
      Hemorrhage                           |                               2                                          |      1  2.0|
      Inflammation, Chronic Active         |                                                                          |      1  1.0|
      Artery, Mineralization               |             1                                                            |      1  1.0|
      Transitional Epithelium, Hyperplasia |                                                                          |      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  41                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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                               | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Foreign Body                         |                      X                                                   |             
      Inflammation, Acute                  |                                                                          |             
      Ulcer                                |                                                                          |             
      Muscularis, Degeneration             |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Colon                  | A  A  +  +  +  +  +  A  +  +  A  A  A  +  +  A  +  A  +  A  +  A  +  A  +|             
      Mineralization                       |                                           1                              |             
                                            __________________________________________________________________________|             
   Intestine Large, Rectum                 | A  A  +  +  +  +  +  A  +  +  A  A  A  +  +  +  +  A  +  A  +  +  +  +  +|             
      Parasite Metazoan                    |                                                                      X   |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Large, Cecum                  | A  A  +  A  +  +  +  A  A  +  A  A  A  +  +  A  +  A  +  A  +  A  +  A  +|             
      Inflammation, Acute                  |                                        2                                 |             
      Inflammation, Chronic                |                                                                          |             
      Ulcer                                |                                                                          |             
                                            __________________________________________________________________________|             
   Intestine Small, Duodenum               | A  +  +  +  +  +  +  A  +  +  A  A  +  +  +  +  +  A  +  A  +  +  +  A  +|             
                                            __________________________________________________________________________|             
   Intestine Small, Jejunum                | A  A  +  +  +  +  +  A  +  +  A  A  A  +  +  +  +  A  +  A  +  A  +  A  +|             
      Inflammation, Chronic                |                                                                   2      |             
                                            __________________________________________________________________________|             
   Intestine Small, Ileum                  | A  A  +  +  +  +  +  A  A  +  A  A  A  +  +  +  +  A  +  A  +  A  +  A  +|             
                                            __________________________________________________________________________|             
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Basophilic Focus                     |                                  X        X                              |             
      Cholangiofibrosis                    |                                                                          |             
      Clear Cell Focus                     |       X     X  X           X                    X                 X     X|             
      Congestion                           |    3                 4              2           2  4        3  3        2|             
      Degeneration, Cystic                 | 1     1        1                                                  1     1|             
      Eosinophilic Focus                   | X                                                                        |             
      Fibrosis                             |    3  2        1     3  1  1  1  3  2     3     1  1           2  1  3   |             
      Hemorrhage                           |                                                                          |             
      Inflammation, Acute                  | 1                                                                        |             
      Mineralization                       |                                           4  2                           |             
      Mixed Cell Focus                     |                            X                                             |             
      Necrosis                             |                                              2                           |             
      Pigmentation                         |    2  2  1  2  1     1  2  2  1  1  2  2  2     1  1     3  1  4  1  1  1|             
      Regeneration                         |                                                                      2   |             
      Vacuolization Cytoplasmic            |    3              1     3  2     1                          1            |             
      Bile Duct, Cyst                      |                                  4           3                           |             
      Bile Duct, Hyperplasia               | 1  1  4     2  1        1  1     3  3  1        1  1              1      |             
      Centrilobular, Cytomegaly            |                                                                          |             
      Centrilobular, Degeneration          |             3  2  3  2  3  1  2        3  2  4  2     1  1        1  3   |             
      Centrilobular, Necrosis              |    2           1  3           4  1                 2     3  2  3     2   |             
      Hepatocyte, Atrophy                  |                                                                          |             
      Periportal, Fibrosis                 |                                  3                       3     2     3   |             
                                            __________________________________________________________________________|             
   Mesentery                               |                                                                         +|             
      Artery, Inflammation                 |                                                                          |             
      Fat, Necrosis                        |                                                                         2|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  42                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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 - cont                  |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Atrophy                              |                   1                                                      |             
      Hyperplasia                          |    4           4        2           2                                   4|             
                                            __________________________________________________________________________|             
   Salivary Glands                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Atrophy                              |                   2                                                      |             
                                            __________________________________________________________________________|             
   Stomach, Forestomach                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cyst                                 |                         2                                                |             
      Fibrosis                             |                                                                          |             
      Foreign Body                         |                                                                          |             
      Hyperplasia, Squamous                |                   3              4                          3           3|             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Chronic Active         |                                                                          |             
      Mineralization                       |                                                                          |             
      Ulcer                                |                                                                         3|             
                                            __________________________________________________________________________|             
   Stomach, Glandular                      | +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Erosion                              |          3              3        2                                       |             
      Mineralization                       | 3                       3              3     3                       2   |             
      Artery, Mineralization               |                                                                          |             
                                            __________________________________________________________________________|             
   Tooth                                   | +                          +                                             |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Chronic                         |                            3                                             |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Chronic Active                  |                                                                          |             
      Peridontal Tissue, Inflammation,     |                                                                          |             
           Suppurative                     | 2                                                                        |             
 _____________________________________________________________________________________________________________________|             
 CARDIOVASCULAR SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Blood Vessel                            |                         +              +     +                           |             
      Aorta, Mineralization                |                         2              4     4                           |             
      Pulmonary Artery, Mineralization     |                         2              4                                 |             
                                            __________________________________________________________________________|             
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Cardiomyopathy                       | 2  2  3  1  3  2  3  4  3  2  2  3  3  2  3  3  2  3  1  3  2  3  3  4  3|             
      Mineralization                       |                         3                 3                              |             
      Artery, Inflammation, Acute          |                            2                                             |             
      Artery, Mineralization               |                                              1                           |             
      Atrium, Dilatation                   |                                                                          |             
      Atrium, Thrombosis                   | 3                                                                        |             
      Valve, Inflammation                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 ENDOCRINE SYSTEM                          |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                   4                                                      |             
      Hyperplasia                          |                                                                          |             
      Necrosis                             |                                                                      2   |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  43                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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                   |                                                                          |             
                                           |                                                                          |             
      Thrombosis                           |                                                                      3   |             
      Vacuolization Cytoplasmic            |          2        3              2              2                        |             
                                            __________________________________________________________________________|             
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |             4                                                            |             
                                            __________________________________________________________________________|             
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Hyperplasia                          |                                                                          |             
                                            __________________________________________________________________________|             
   Parathyroid Gland                       | +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia                          |                         4              4  3  4                       2   |             
                                            __________________________________________________________________________|             
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Angiectasis                          |                                                                         2|             
      Congestion                           |             2                       2                                    |             
      Cyst                                 | 2              2                    2                       2            |             
      Hemorrhage                           |                                                                1         |             
      Hyperplasia                          | 3                                                                 2      |             
      Hypertrophy                          |                1                                                         |             
                                            __________________________________________________________________________|             
   Thyroid Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Follicle, Cyst                       |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENERAL BODY SYSTEM                       |                                                                          |             
                                           |                                                                          |             
    None                                   |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Coagulating Gland                       | M  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic                |                                              2                           |             
                                            __________________________________________________________________________|             
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Artery, Inflammation                 |                                                                          |             
      Epithelium, Hyperplasia              |                                                                          |             
                                            __________________________________________________________________________|             
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Squamous                |    3                                                                     |             
      Inflammation, Chronic                |                                                                          |             
      Inflammation, Suppurative            |             2                                                            |             
      Duct, Cyst                           | 4  3  3  3  2  1  1  4  1  4  4  2  1  4  2  1  2  2  2  1  3  1  2  4  3|             
                                            __________________________________________________________________________|             
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrosis                             |                                                                         2|             
      Hyperplasia                          |             1                                                            |             
      Inflammation, Chronic                |                                              2                           |             
      Inflammation, Chronic Active         |                                                                          |             
                                            __________________________________________________________________________|             
   Seminal Vesicle                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |          2     1  4     1        3     2                                 |             
      Congestion                           |          2                                                               |             
      Inflammation, Granulomatous          |                                                                          |             
      Mineralization                       |                                           1                          1   |             
      Artery, Inflammation                 |             3           2                    2                       3   |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  44                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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|             
 _____________________________________________________________________________________________________________________|             
 GENITAL SYSTEM - cont                     |                                                                          |             
                                           |                                                                          |             
      Interstitial Cell, Hyperplasia       |                            1              4                 2            |             
 _____________________________________________________________________________________________________________________|             
 HEMATOPOIETIC SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                   2                                                      |             
                                            __________________________________________________________________________|             
   Lymph Node                              |          +  +  +                 +     +  +  +  +  +     +  +  +     +   |             
      Iliac, Ectasia                       |                                              2                           |             
      Iliac, Hemorrhage                    |                                  2                 3                     |             
      Iliac, Hyperplasia, Lymphoid         |                                                                2         |             
      Iliac, Hyperplasia, Plasma Cell      |                                              2                           |             
      Inguinal, Hemorrhage                 |                                                    4                     |             
      Mediastinal, Congestion              |                                                                3         |             
      Mediastinal, Ectasia                 |                                                             2            |             
      Mediastinal, Hemorrhage              |          1                       3           3  2  4                 1   |             
      Mediastinal, Hyperplasia, Lymphoid   |                                                                      2   |             
      Mediastinal, Hyperplasia, Plasma Cell|                                                                          |             
      Pancreatic, Ectasia                  |                                                                          |             
      Pancreatic, Hemorrhage               |                                  2                 2           2         |             
      Pancreatic, Hyperplasia, Lymphoid    |                                                                3         |             
      Pancreatic, Hyperplasia, Plasma Cell |                                           3  3                           |             
      Renal, Ectasia                       |                                  2     2     3                           |             
      Renal, Hemorrhage                    |                2                 2     2     2     3           3         |             
      Renal, Hyperplasia, Lymphoid         |                                                                          |             
      Renal, Hyperplasia, Plasma Cell      |                                                                          |             
                                            __________________________________________________________________________|             
   Lymph Node, Mandibular                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +|             
      Congestion                           |                      3        2                             2            |             
      Ectasia                              |       3        4                 1                          2            |             
      Hemorrhage                           |                                                                          |             
      Hyperplasia, Lymphoid                |                                                                          |             
      Hyperplasia, Plasma Cell             |             3                                               4            |             
                                            __________________________________________________________________________|             
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              |                   3                                                      |             
      Ectasia                              |                                                                          |             
      Hemorrhage                           |       2  2        1  1                    1        1                    2|             
      Hyperplasia, Lymphoid                |                                                                2         |             
      Hyperplasia, Plasma Cell             |                                                                   2      |             
                                            __________________________________________________________________________|             
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|             
      Atrophy                              |                                                                          |             
      Fibrosis                             |                                                                          |             
      Hematopoietic Cell Proliferation     |          4                       3                                       |             
                                            __________________________________________________________________________|             
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Atrophy                              | 3        4        4  4  4     1  4     4  4  4     3        4        3  2|             
      Cyst                                 |             2                                                            |             
      Ectopic Parathyroid Gland            |                                              2                           |             
 _____________________________________________________________________________________________________________________|             

                                                             Page  45                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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               |                                                                          |             
                                           |                                                                          |             
      Hemorrhage                           |                               2                                3         |             
      Hyperplasia, Squamous                |                1           1                                             |             
 _____________________________________________________________________________________________________________________|             
 INTEGUMENTARY SYSTEM                      |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Mammary Gland                           | M  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +  +  +  +  M  +  +  +  +|             
      Cyst                                 |                                                                          |             
      Hyperplasia                          |                                                                          |             
      Duct, Dilatation                     |             2     1                                                      |             
                                            __________________________________________________________________________|             
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Hyperplasia, Squamous                |             2                                                        3   |             
      Inflammation, Chronic                |             3                                                            |             
      Inflammation, Suppurative            | 4                                                                        |             
      Ulcer                                |                                                                         3|             
      Hair Follicle, Cyst                  |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 MUSCULOSKELETAL SYSTEM                    |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Fibrous Osteodystrophy               |                      1  2              2  1  3                           |             
      Cartilage, Degeneration              |                                                                          |             
      Cranium, Fibrous Osteodystrophy      |                         2                    2                           |             
      Joint, Arthrosis                     |                                                                      4   |             
      Joint, Fibrosis                      |                            3                                             |             
      Joint, Inflammation, Chronic         |                            4                                             |             
      Mandible, Hyperplasia                | 3                                                                        |             
      Metacarpal, Inflammation, Chronic    |                                                                          |             
          Active                           |                                                                          |             
      Metatarsal, Inflammation, Chronic    |                                                                          |             
          Active                           |                                                                          |             
      Periosteum, Hyperplasia              |             4                                                            |             
      Vertebra, Inflammation, Chronic      |                            4                                             |             
 _____________________________________________________________________________________________________________________|             
 NERVOUS SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
                                            __________________________________________________________________________|             
   Peripheral Nerve                        |                            +                          +                 +|             
      Radicular Neuropathy                 |                                                                         2|             
                                            __________________________________________________________________________|             
   Spinal Cord                             |                            +                          +                 +|             
 _____________________________________________________________________________________________________________________|             
 RESPIRATORY SYSTEM                        |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           | 2  2                    2                                                |             
      Hemorrhage                           |          2                                   4     2     1               |             
      Inflammation, Granulomatous          |                2                                                        1|             
      Interstitium, Fibrosis               |                                              2                           |             
                                            __________________________________________________________________________|             
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  46                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 _____________________________________________________________________________________________________________________              
                                           | 7| 5| 7| 5| 7| 7| 5| 4| 6| 7| 4| 6| 6| 4| 5| 4| 7| 6| 5| 5| 4| 5| 7| 6| 6|             
                             DAY ON TEST   | 0| 8| 2| 3| 2| 2| 9| 4| 0| 2| 5| 7| 8| 9| 5| 8| 2| 8| 3| 3| 6| 6| 2| 8| 3|             
                                           | 9| 7| 2| 9| 2| 2| 5| 3| 6| 2| 0| 4| 2| 9| 0| 6| 2| 5| 2| 1| 7| 8| 2| 7| 1|             
 _____________________________________________________________________________________________________________________|             
                                           | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|             
                               ANIMAL ID   | 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1| 1|             
    400 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                 |                                                                          |             
                                           |                                                                          |             
      Foreign Body                         |                                                             X            |             
      Inflammation, Acute                  |                      1                                                   |             
      Inflammation, Chronic                |                            1                                             |             
      Inflammation, Chronic Active         |                4                          3                 4            |             
      Metaplasia, Squamous                 |                                                             2            |             
      Artery, Thrombosis                   |          3                                                               |             
      Respiratory Epithelium, Hyperplasia  |                   2                       3                    2  2     1|             
                                            __________________________________________________________________________|             
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Inflammation, Chronic Active         |                                                                          |             
 _____________________________________________________________________________________________________________________|             
 SPECIAL SENSES SYSTEM                     |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Ear                                     |                                                       +                  |             
                                            __________________________________________________________________________|             
   Harderian Gland                         |                                                                          |             
      Inflammation, Chronic                |                                                                          |             
                                            __________________________________________________________________________|             
   Zymbal's Gland                          |                                                                      +   |             
 _____________________________________________________________________________________________________________________|             
 URINARY SYSTEM                            |                                                                          |             
                                           |                                                                          |             
                                            __________________________________________________________________________|             
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|             
      Congestion                           |                      4              3                                    |             
      Cyst                                 |       1     1           2  2        2  4  2  2     1                    2|             
      Hydronephrosis                       |                               2  2                       1  2     2  1   |             
      Inflammation, Acute                  |                                                                          |             
      Mineralization                       |                                        1     1                           |             
      Nephropathy                          | 2  3  4  2  3  3  4  4  4  3  4  3  3  4  4  4  3  3  2  4  2  4  2  4  3|             
      Renal Tubule, Accumulation, Hyaline  |                                                                          |             
          Droplet                          |          2                                                               |             
      Renal Tubule, Hyperplasia            |                                        3                       4         |             
      Vein, Thrombosis                     |                                                                          |             
                                            __________________________________________________________________________|             
   Urinary Bladder                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  A  +  A  +  A  +|             
 _____________________________________________________________________________________________________________________|             

                                                             Page  47                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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        |
      Foreign Body                         |                                                                          |      1     |
      Inflammation, Acute                  |                                              4                           |      1  4.0|
      Ulcer                                |                                              2                           |      1  2.0|
      Muscularis, Degeneration             |                   2                                                      |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Colon                  | +  A  +  +  +  A  A  +  A  +  +  +  +  +  +  +  +  A  +  +  +  +  +  A  +|  33        |
      Mineralization                       |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Rectum                 | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +|  40        |
      Parasite Metazoan                    |                                                                          |      1     |
      Ulcer                                |                                        1                                 |      1  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Large, Cecum                  | A  A  +  +  +  A  A  +  A  A  +  +  +  +  A  +  +  A  +  A  +  +  +  A  +|  27        |
      Inflammation, Acute                  |                                                                          |      1  2.0|
      Inflammation, Chronic                |                                                       2                  |      1  2.0|
      Ulcer                                |                                        1              1                  |      2  1.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Duodenum               | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  42        |
                                            __________________________________________________________________________|____________|
   Intestine Small, Jejunum                | +  A  +  +  +  A  A  +  +  A  +  +  +  +  +  +  +  A  +  +  +  +  +  +  +|  35        |
      Inflammation, Chronic                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Intestine Small, Ileum                  | +  A  A  A  +  A  +  +  +  A  +  +  +  +  +  +  +  A  +  A  +  +  +  A  +|  31        |
                                            __________________________________________________________________________|____________|
   Liver                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Basophilic Focus                     |                                                                          |      2     |
      Cholangiofibrosis                    |                                           2                              |      1  2.0|
      Clear Cell Focus                     |                                                                   X      |      8     |
      Congestion                           | 3     3  4           2        2           3     3  3        3            |     17  2.9|
      Degeneration, Cystic                 |                                                                          |      5  1.0|
      Eosinophilic Focus                   |                                           X                              |      2     |
      Fibrosis                             | 2  1  2        2        3  3  1     2  1  2  1     1        1  2     2  1|     31  1.8|
      Hemorrhage                           |    1                                   2                 3               |      3  2.0|
      Inflammation, Acute                  |                                                                          |      1  1.0|
      Mineralization                       |                                                 1                        |      3  2.3|
      Mixed Cell Focus                     |                                                                          |      1     |
      Necrosis                             |                                                             1            |      2  1.5|
      Pigmentation                         | 3  1  3        2     1  3  2  2  2  2  3  1  1  1  2  3     1  3  1  1  3|     42  1.8|
      Regeneration                         |                         2                                                |      2  2.0|
      Vacuolization Cytoplasmic            |    3  2  1     2  1  2           2           2              2            |     15  1.9|
      Bile Duct, Cyst                      |                                           2                              |      3  3.0|
      Bile Duct, Hyperplasia               |    3     2     3  2  2  3  3        3  1     2           2  1     1     2|     27  1.9|
      Centrilobular, Cytomegaly            |                                                             3            |      1  3.0|
      Centrilobular, Degeneration          | 3  4  3  3     1        1  3  2  2  2  3  4  2  3  3              1  4  2|     33  2.4|
      Centrilobular, Necrosis              | 2  1           4        3  3        2  3        2  2     3     3     3  3|     23  2.5|
 __________________________________________________________________________________________________________________________________ 

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

                                                             Page  48                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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                  |                                                                          |            |
                                           |                                                                          |            |
      Hepatocyte, Atrophy                  |                                                             2            |      1  2.0|
      Periportal, Fibrosis                 |                            2        2                                   2|      7  2.4|
                                            __________________________________________________________________________|____________|
   Mesentery                               |                                        +                                 |   2        |
      Artery, Inflammation                 |                                        4                                 |      1  4.0|
      Fat, Necrosis                        |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Pancreas                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |                                                                          |      1  1.0|
      Hyperplasia                          |                                              3  3                 4      |      8  3.3|
                                            __________________________________________________________________________|____________|
   Salivary Glands                         | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Atrophy                              |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Stomach, Forestomach                    | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Cyst                                 |                                                    2                     |      2  2.0|
      Fibrosis                             |                      2                                                   |      1  2.0|
      Foreign Body                         |          X           X                                                   |      2     |
      Hyperplasia, Squamous                |          4        1  4                    1  3              4            |     10  3.0|
      Inflammation, Chronic                |                                                             2            |      1  2.0|
      Inflammation, Chronic Active         |          3                                                               |      1  3.0|
      Mineralization                       |                                        1                                 |      1  1.0|
      Ulcer                                |                      1        4                             2            |      4  2.5|
                                            __________________________________________________________________________|____________|
   Stomach, Glandular                      | +  +  +  +  +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Erosion                              |    3                                                                     |      4  2.8|
      Mineralization                       |                                        2                                 |      6  2.7|
      Artery, Mineralization               |                   1                                                      |      1  1.0|
                                            __________________________________________________________________________|____________|
   Tooth                                   |                                                             +            |   3        |
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Chronic                         |                                                                          |      1  3.0|
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Chronic Active                  |                                                             2            |      1  2.0|
      Peridontal Tissue, Inflammation,     |                                                                          |            |
           Suppurative                     |                                                                          |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 CARDIOVASCULAR SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Blood Vessel                            |                                                                          |   3        |
      Aorta, Mineralization                |                                                                          |      3  3.3|
      Pulmonary Artery, Mineralization     |                                                                          |      2  3.0|
                                            __________________________________________________________________________|____________|
   Heart                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Cardiomyopathy                       | 2  4  2        3  2     3  2  1  2  2  2  3  3  2  3  2  3  3  3  3  1  4|     47  2.6|
      Mineralization                       |                   2                                                      |      3  2.7|
      Artery, Inflammation, Acute          |                                                                          |      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  49                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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              |                                                                          |            |
                                           |                                                                          |            |
      Artery, Mineralization               |                   3                                                      |      2  2.0|
      Atrium, Dilatation                   |                                     3                                    |      1  3.0|
      Atrium, Thrombosis                   |    4                                               3                     |      3  3.3|
      Valve, Inflammation                  |                                                    2                     |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 ENDOCRINE SYSTEM                          |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Adrenal Cortex                          | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      1  4.0|
      Hyperplasia                          |                                                                3         |      1  3.0|
      Necrosis                             |                                           2                              |      2  2.0|
      Thrombosis                           |                                                                          |      1  3.0|
      Vacuolization Cytoplasmic            |                      2                       1                    3      |      7  2.1|
                                            __________________________________________________________________________|____________|
   Adrenal Medulla                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia                          |                                                                          |      1  4.0|
                                            __________________________________________________________________________|____________|
   Islets, Pancreatic                      | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Hyperplasia                          |    3                                                                     |      1  3.0|
                                            __________________________________________________________________________|____________|
   Parathyroid Gland                       | M  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  47        |
      Hyperplasia                          |       3           2                       2  1  1  2     2               |     12  2.5|
                                            __________________________________________________________________________|____________|
   Pituitary Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Angiectasis                          |                                                                          |      1  2.0|
      Congestion                           |                                                                          |      2  2.0|
      Cyst                                 |                   3        2     1  1                 2           2     2|     11  1.9|
      Hemorrhage                           |                                                                          |      1  1.0|
      Hyperplasia                          |       4                                                                  |      3  3.0|
      Hypertrophy                          |                                                                          |      1  1.0|
                                            __________________________________________________________________________|____________|
   Thyroid Gland                           | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Follicle, Cyst                       |                                           1                              |      1  1.0|
 _____________________________________________________________________________________________________________________|            |
 GENERAL BODY SYSTEM                       |                                                                          |            |
                                           |                                                                          |            |
    None                                   |                                                                          |            |
 _____________________________________________________________________________________________________________________|            |
 GENITAL SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Coagulating Gland                       | +  A  +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +|  45        |
      Inflammation, Chronic                |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Epididymis                              | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Artery, Inflammation                 |                                     2                                    |      1  2.0|
      Epithelium, Hyperplasia              |                   2                                                      |      1  2.0|
                                            __________________________________________________________________________|____________|
   Preputial Gland                         | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia, Squamous                |                                                                          |      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  50                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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|            |
 __________________________________________________________________________________________________________________________________ 
 GENITAL SYSTEM - cont                     |                                                                          |            |
                                           |                                                                          |            |
      Inflammation, Chronic                | 2                                                                        |      1  2.0|
      Inflammation, Suppurative            |                                                    4  2                  |      3  2.7|
      Duct, Cyst                           | 2     3  4     2  4  2  1  1  2  1  3  2  1  1  2  3  4  2  2  3  4  1  2|     48  2.3|
                                            __________________________________________________________________________|____________|
   Prostate                                | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrosis                             |                                                                          |      1  2.0|
      Hyperplasia                          |                                           1                              |      2  1.0|
      Inflammation, Chronic                |                      1                                                   |      2  1.5|
      Inflammation, Chronic Active         |                                              4              1            |      2  2.5|
                                            __________________________________________________________________________|____________|
   Seminal Vesicle                         | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
                                            __________________________________________________________________________|____________|
   Testes                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |    2                                                        4     2      |      9  2.3|
      Congestion                           |                                                                          |      1  2.0|
      Inflammation, Granulomatous          |                                                                   3      |      1  3.0|
      Mineralization                       |                                                                   2     1|      4  1.3|
      Artery, Inflammation                 | 1  3                       2                 1     1           1  1      |     11  1.8|
      Interstitial Cell, Hyperplasia       |                               2     3           4     4                  |      7  2.9|
 _____________________________________________________________________________________________________________________|            |
 HEMATOPOIETIC SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone Marrow                             | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Lymph Node                              | +  +  +  +  +  +  +  +        +  +  +  +  +  +     +     +        +  +  +|  32        |
      Iliac, Ectasia                       |                                                                          |      1  2.0|
      Iliac, Hemorrhage                    |          2                                                               |      3  2.3|
      Iliac, Hyperplasia, Lymphoid         |                                                                          |      1  2.0|
      Iliac, Hyperplasia, Plasma Cell      |          2                                                               |      2  2.0|
      Inguinal, Hemorrhage                 |                                                                          |      1  4.0|
      Mediastinal, Congestion              |                                                                          |      1  3.0|
      Mediastinal, Ectasia                 |    2     1     1  2                    2                                 |      6  1.7|
      Mediastinal, Hemorrhage              |          3     1                       2                                 |      9  2.2|
      Mediastinal, Hyperplasia, Lymphoid   |                                                                          |      1  2.0|
      Mediastinal, Hyperplasia, Plasma Cell|                   2                                                      |      1  2.0|
      Pancreatic, Ectasia                  |                1                                                         |      1  1.0|
      Pancreatic, Hemorrhage               |       2  2     3                       2                                 |      7  2.1|
      Pancreatic, Hyperplasia, Lymphoid    | 2                    3                 3                                 |      4  2.8|
      Pancreatic, Hyperplasia, Plasma Cell |                                                                          |      2  3.0|
      Renal, Ectasia                       | 4     3                             2  4                 3        3  1   |     10  2.7|
      Renal, Hemorrhage                    | 2                                   2     3                       2  3  2|     12  2.3|
      Renal, Hyperplasia, Lymphoid         |                                     2                                   2|      2  2.0|
      Renal, Hyperplasia, Plasma Cell      |          2                                                        2      |      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  51                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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               |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lymph Node, Mandibular                  | +  M  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  48        |
      Congestion                           |                                                                      3   |      4  2.5|
      Ectasia                              |       2                    3     4        2  1                    2      |     10  2.4|
      Hemorrhage                           |                                                             3            |      1  3.0|
      Hyperplasia, Lymphoid                |                                                          3               |      1  3.0|
      Hyperplasia, Plasma Cell             |             4                                               3            |      4  3.5|
                                            __________________________________________________________________________|____________|
   Lymph Node, Mesenteric                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |                                           2                              |      2  2.5|
      Ectasia                              |       1        1           2        1              1                     |      5  1.2|
      Hemorrhage                           |    2  1                             1  2                             1   |     12  1.4|
      Hyperplasia, Lymphoid                |             4              2        2                    2               |      5  2.4|
      Hyperplasia, Plasma Cell             |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Spleen                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  49        |
      Atrophy                              |                                              4                           |      1  4.0|
      Fibrosis                             |    2                                                                     |      1  2.0|
      Hematopoietic Cell Proliferation     |                                                                          |      2  3.5|
                                            __________________________________________________________________________|____________|
   Thymus                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Atrophy                              |    4     3     3              1        2  3  4     3        2        2   |     24  3.1|
      Cyst                                 |       1        1           1                 1        2                  |      6  1.3|
      Ectopic Parathyroid Gland            |                                                                          |      1  2.0|
      Hemorrhage                           |       1  3  1     1     1  3        2           2        3     3     3  2|     14  2.1|
      Hyperplasia, Squamous                |                                                                          |      2  1.0|
 _____________________________________________________________________________________________________________________|            |
 INTEGUMENTARY SYSTEM                      |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Mammary Gland                           | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  M  +  +  +  +  +  +|  46        |
      Cyst                                 |                                              1                           |      1  1.0|
      Hyperplasia                          |             3  2        1        1                                       |      4  1.8|
      Duct, Dilatation                     |                                                             1  1         |      4  1.3|
                                            __________________________________________________________________________|____________|
   Skin                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Hyperplasia, Squamous                |                                                                          |      2  2.5|
      Inflammation, Chronic                |                                                                          |      1  3.0|
      Inflammation, Suppurative            |                                                                          |      1  4.0|
      Ulcer                                |          4                                                               |      2  3.5|
      Hair Follicle, Cyst                  |                                                             2            |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 MUSCULOSKELETAL SYSTEM                    |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Bone                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Fibrous Osteodystrophy               |                                                                         1|      6  1.7|
      Cartilage, Degeneration              |                                                                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  52                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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|            |
 __________________________________________________________________________________________________________________________________ 
 MUSCULOSKELETAL SYSTEM - cont             |                                                                          |            |
                                           |                                                                          |            |
      Cranium, Fibrous Osteodystrophy      |                                                                          |      2  2.0|
      Joint, Arthrosis                     |                                                                          |      1  4.0|
      Joint, Fibrosis                      |                                                                          |      1  3.0|
      Joint, Inflammation, Chronic         |                                                                          |      1  4.0|
      Mandible, Hyperplasia                |                                                                          |      1  3.0|
      Metacarpal, Inflammation, Chronic    |                                                                          |            |
          Active                           |             4                                                            |      1  4.0|
      Metatarsal, Inflammation, Chronic    |                                                                          |            |
          Active                           |             4                                                            |      1  4.0|
      Periosteum, Hyperplasia              |                                                                          |      1  4.0|
      Vertebra, Inflammation, Chronic      |                                                                          |      1  4.0|
 _____________________________________________________________________________________________________________________|            |
 NERVOUS SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Brain                                   | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
                                            __________________________________________________________________________|____________|
   Peripheral Nerve                        |                                                       +              +   |   5        |
      Radicular Neuropathy                 |                                                       1                  |      2  1.5|
                                            __________________________________________________________________________|____________|
   Spinal Cord                             |                                                       +                  |   4        |
 _____________________________________________________________________________________________________________________|            |
 RESPIRATORY SYSTEM                        |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Lung                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                          3               |      4  2.3|
      Hemorrhage                           |                   1                                2  1                  |      7  1.9|
      Inflammation, Granulomatous          |                                                                          |      2  1.5|
      Interstitium, Fibrosis               |                                                                          |      1  2.0|
                                            __________________________________________________________________________|____________|
   Nose                                    | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Foreign Body                         |                                                                          |      1     |
      Inflammation, Acute                  |                   2                                                      |      2  1.5|
      Inflammation, Chronic                |                                                                          |      1  1.0|
      Inflammation, Chronic Active         |                                  1                          1        2   |      6  2.5|
      Metaplasia, Squamous                 |                                  2                                       |      2  2.0|
      Artery, Thrombosis                   |                                                                          |      1  3.0|
      Respiratory Epithelium, Hyperplasia  | 2           3  2        1                 3  1  3     1  1        1      |     15  1.9|
                                            __________________________________________________________________________|____________|
   Trachea                                 | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Inflammation, Chronic Active         |                   2                                                      |      1  2.0|
 _____________________________________________________________________________________________________________________|            |
 SPECIAL SENSES SYSTEM                     |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Ear                                     |                                                                          |   1        |
                                            __________________________________________________________________________|____________|
   Harderian Gland                         |                                  +                                       |   1        |
      Inflammation, Chronic                |                                  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  53                                                               
NTP Experiment-Test: 55301-06                  NONNEOPLASTIC LESIONS BY INDIVIDUAL ANIMAL                         Report: PEIRPT09
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97  
Route: DOSED WATER                                                                                                Time: 12:22:11  
                                                                                                                                    
 __________________________________________________________________________________________________________________________________ 
                                           | 5| 6| 4| 4| 0| 5| 5| 4| 5| 6| 4| 6| 5| 4| 6| 6| 4| 5| 5| 5| 6| 5| 7| 4| 5|            |
                             DAY ON TEST   | 1| 1| 8| 6| 9| 4| 5| 6| 5| 2| 9| 8| 5| 6| 5| 6| 8| 8| 8| 5| 2| 6| 2| 6| 7|            |
                                           | 1| 6| 9| 8| 4| 5| 2| 6| 6| 9| 3| 3| 3| 3| 8| 0| 3| 0| 2| 3| 7| 2| 2| 4| 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     |
   WISTAR OUTBRED RATS MALE                | 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0| 0|      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     |
    400 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|            |
 __________________________________________________________________________________________________________________________________ 
 SPECIAL SENSES SYSTEM - cont              |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Zymbal's Gland                          |                      +           +                                       |   3        |
 _____________________________________________________________________________________________________________________|            |
 URINARY SYSTEM                            |                                                                          |            |
                                           |                                                                          |            |
                                            __________________________________________________________________________|____________|
   Kidney                                  | +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +|  50        |
      Congestion                           |                                                                          |      2  3.5|
      Cyst                                 |                4        2              2  2        2              2      |     16  2.1|
      Hydronephrosis                       | 2                                            1  4  1  1  1  1     2     2|     15  1.7|
      Inflammation, Acute                  |                                              1                           |      1  1.0|
      Mineralization                       |                   3                          1                    1      |      5  1.4|
      Nephropathy                          | 4  4  4  2  1  3  3  2  3  4  2  3  3  4  4  4  4  4  2  4  4  3  2  4  4|     50  3.2|
      Renal Tubule, Accumulation, Hyaline  |                                                                          |            |
          Droplet                          |                                                                          |      1  2.0|
      Renal Tubule, Hyperplasia            |                            4           1           1                     |      5  2.6|
      Vein, Thrombosis                     |    3                                      3                 2            |      3  2.7|
                                            __________________________________________________________________________|____________|
   Urinary Bladder                         | +  A  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  +  A  +  +  +  +  +|  44        |
 __________________________________________________________________________________________________________________________________ 

  * : 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                                                               
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------