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TDMS Study 55301-05 Pathology Tables

NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97
Route: DOSED WATER                                                                                                Time: 11:55:09




       Facility:  TSI Mason Research

       Chemical CAS #:  110-86-1

       Lock Date:  12/15/94

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All




































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

                                                              Page   1


NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 

  Animals Initially in Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                     15            5           14           22                                     
    Moribund Sacrifice                                 3            8            7            2                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                32           37           29           26                                     

  Animals Examined Microscopically                    50           50           50           50                                     
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (50)         (50)         (50)         (50)                                   
      Schwannoma Malignant, Metastatic, Uterus                      1 (2%)                                                          
   Intestine Large, Colon                             (50)         (50)         (50)         (50)                                   
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Intestine Large, Cecum                             (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Intestine Small, Duodenum                          (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Intestine Small, Jejunum                           (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Intestine Small, Ileum                             (50)         (49)         (50)         (50)                                   
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Liver                                              (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
      Hepatocellular Adenoma                           1 (2%)                    1 (2%)                                             
   Mesentery                                          (9)          (11)         (7)          (12)                                   
      Carcinoma, Metastatic, Uterus                                 1 (9%)                                                          
      Fibrous Histiocytoma                             1 (11%)                                                                      
      Schwannoma Malignant, Metastatic, Uterus                      1 (9%)                                                          
   Oral Mucosa                                        (2)          (1)                       (2)                                    
      Pharyngeal, Squamous Cell Carcinoma              2 (100%)                                                                     
      Pharyngeal, Squamous Cell Papilloma                                                     1 (50%)                               
   Pancreas                                           (49)         (50)         (50)         (50)                                   
      Carcinoma                                                     2 (4%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       

                                                             Page   2                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - cont                                                                                                            
      Acinus, Adenoma                                               1 (2%)                    1 (2%)                                
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
   Stomach, Glandular                                 (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Tongue                                                                       (1)          (2)                                    
      Squamous Cell Papilloma                                                                 1 (50%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (49)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
   Adrenal Medulla                                    (50)         (50)         (50)         (49)                                   
      Pheochromocytoma Benign                          2 (4%)                    1 (2%)                                             
      Bilateral, Pheochromocytoma Benign               1 (2%)                                                                       
   Islets, Pancreatic                                 (49)         (50)         (50)         (50)                                   
      Adenoma                                          1 (2%)                    1 (2%)                                             
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Parathyroid Gland                                  (48)         (50)         (48)         (50)                                   
   Pituitary Gland                                    (49)         (50)         (50)         (50)                                   
      Pars Distalis, Adenoma                          17 (35%)     12 (24%)     18 (36%)     15 (30%)                               
      Pars Distalis, Adenoma, Multiple                 1 (2%)                                                                       
   Thyroid Gland                                      (50)         (50)         (50)         (50)                                   
      Bilateral, C-Cell, Adenoma                                    1 (2%)                                                          
      C-Cell, Adenoma                                  3 (6%)       2 (4%)       2 (4%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (47)         (48)         (50)         (49)                                   
      Adenoma                                          2 (4%)       3 (6%)                    1 (2%)                                
      Carcinoma                                                     1 (2%)       1 (2%)       2 (4%)                                
      Bilateral, Adenoma                                                         1 (2%)                                             
   Ovary                                              (50)         (50)         (50)         (50)                                   

                                                             Page   3                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - cont                                                                                                               
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
      Granulosa-Theca Tumor Malignant                                            1 (2%)                                             
   Uterus                                             (50)         (50)         (50)         (50)                                   
      Carcinoma                                                     1 (2%)                                                          
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Polyp Stromal                                    4 (8%)       7 (14%)      9 (18%)      7 (14%)                               
      Polyp Stromal, Multiple                                                                 1 (2%)                                
      Sarcoma Stromal                                  1 (2%)                                                                       
      Schwannoma Malignant, Metastatic, Uterus                      1 (2%)                                                          
   Vagina                                                                                    (1)                                    
      Lipoma                                                                                  1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
   Lymph Node                                         (7)          (9)          (15)         (19)                                   
      Mediastinal, Carcinoma, Metastatic, Kidney                    1 (11%)                                                         
      Mediastinal, Carcinoma, Metastatic, Pancreas                  1 (11%)                                                         
      Mediastinal, Fibrous Histiocytoma,                                                                                            
          Metastatic, Mesentery                        1 (14%)                                                                      
   Lymph Node, Mandibular                             (49)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
   Lymph Node, Mesenteric                             (49)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
      Fibrous Histiocytoma, Metastatic, Mesentery      1 (2%)                                                                       
   Spleen                                             (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
   Thymus                                             (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (50)         (50)         (50)         (50)                                   
      Adenoma                                          2 (4%)       1 (2%)       1 (2%)                                             
      Carcinoma                                        1 (2%)       2 (4%)       1 (2%)       1 (2%)                                
      Fibroadenoma                                    19 (38%)     15 (30%)     14 (28%)     18 (36%)                               
      Fibroadenoma, Multiple                           8 (16%)     10 (20%)      6 (12%)      2 (4%)                                
      Sarcoma                                          1 (2%)                                                                       

                                                             Page   4                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
INTEGUMENTARY SYSTEM - cont                                                                                                         
   Skin                                               (50)         (50)         (50)         (50)                                   
      Basal Cell Adenoma                                            1 (2%)                                                          
      Keratoacanthoma                                                                         1 (2%)                                
      Trichoepithelioma                                                                       1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Skeletal Muscle                                    (2)          (1)                                                              
      Carcinoma, Metastatic, Uterus                                 1 (100%)                                                        
      Abdominal, Fibrous Histiocytoma, Metastatic,                                                                                  
           Mesentery                                   1 (50%)                                                                      
      Abdominal, Lipoma                                1 (50%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Astrocytoma Malignant                            2 (4%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (50)         (50)         (50)         (50)                                   
      Alveolar/Bronchiolar Adenoma                     1 (2%)       1 (2%)       1 (2%)       2 (4%)                                
      Carcinoma, Metastatic, Clitoral Gland                                                   1 (2%)                                
      Carcinoma, Metastatic, Kidney                                 1 (2%)                                                          
      Carcinoma, Metastatic, Mammary Gland                                       1 (2%)                                             
      Carcinoma, Metastatic, Pancreas                               2 (4%)                                                          
      Carcinoma, Metastatic, Uterus                                 1 (2%)                                                          
   Nose                                               (50)         (50)         (50)         (50)                                   
   Pleura                                                          (1)                                                              
      Carcinoma, Metastatic, Kidney                                 1 (100%)                                                        
   Trachea                                            (50)         (50)         (50)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Zymbal's Gland                                                  (1)                       (1)                                    
      Carcinoma                                                     1 (100%)                  1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

                                                             Page   5                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (50)         (50)                                   
      Carcinoma, Metastatic, Pancreas                               1 (2%)                                                          
      Transitional Epithelium, Carcinoma                            1 (2%)                                                          
   Urinary Bladder                                    (50)         (50)         (50)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   

   Multiple Organs                                   *(50)        *(50)        *(50)        *(50)                                   
      Leukemia Mononuclear                            12 (24%)     16 (32%)     22 (44%)     23 (46%)                               
      Lymphoma Malignant                               1 (2%)                                 1 (2%)                                
____________________________________________________________________________________________________________________________________

                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 

                                                             Page   6                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS FEMALE                   0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            45          42          45          44                                       
     Total Primary Neoplasms                           84          78          80          80                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 39          34          35          35                                       
     Total Benign Neoplasms                            63          54          55          52                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              21          22          23          28                                       
     Total Malignant Neoplasms                         21          24          25          28                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              1           5           1           1                                       
     Total Metastatic Neoplasm                         13          36           1           1                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    

____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              

                                                             Page   7                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
DISPOSITION SUMMARY                                                                                                                 

  Animals Initially in Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                11           13           15           10                                     
    Natural Death                                     14           17           10           24                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                25           20           25           16                                     

  Animals Examined Microscopically                    50           50           50           50                                     
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (50)         (48)         (50)         (49)                                   
      Lipoma                                                                     1 (2%)                                             
   Intestine Large, Cecum                             (49)         (47)         (50)         (49)                                   
      Lipoma                                                                     1 (2%)                                             
   Intestine Small, Duodenum                          (50)         (47)         (50)         (48)                                   
   Intestine Small, Jejunum                           (50)         (47)         (50)         (47)                                   
      Carcinoma                                        1 (2%)                                                                       
   Intestine Small, Ileum                             (50)         (47)         (50)         (47)                                   
   Liver                                              (50)         (49)         (50)         (50)                                   
      Cholangiocarcinoma                                                                      1 (2%)                                
      Hepatocellular Carcinoma                                                   1 (2%)                                             
      Hepatocellular Adenoma                           1 (2%)       1 (2%)                    2 (4%)                                
      Hepatocellular Adenoma, Multiple                                                        1 (2%)                                
      Histiocytic Sarcoma                              1 (2%)                                                                       
   Mesentery                                          (11)         (14)         (7)          (8)                                    
      Schwannoma Benign                                1 (9%)                                                                       
   Oral Mucosa                                        (1)                       (2)                                                 
      Pharyngeal, Squamous Cell Papilloma              1 (100%)                  1 (50%)                                            
   Pancreas                                           (50)         (48)         (50)         (49)                                   
      Acinus, Adenoma                                  2 (4%)       1 (2%)       1 (2%)       1 (2%)                                
   Salivary Glands                                    (50)         (50)         (50)         (50)                                   
   Stomach, Forestomach                               (50)         (49)         (50)         (49)                                   
      Squamous Cell Papilloma                                                    1 (2%)                                             
   Stomach, Glandular                                 (50)         (49)         (50)         (49)                                   
   Tongue                                                                                    (1)                                    
      Squamous Cell Papilloma                                                                 1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

                                                             Page   8                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (50)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (49)         (50)         (50)                                   
      Carcinoma                                                     1 (2%)                                                          
   Adrenal Medulla                                    (50)         (49)         (50)         (49)                                   
      Pheochromocytoma Complex                                                                1 (2%)                                
      Pheochromocytoma Benign                         11 (22%)      2 (4%)      14 (28%)      4 (8%)                                
      Bilateral, Pheochromocytoma Benign               6 (12%)      1 (2%)                                                          
   Islets, Pancreatic                                 (50)         (48)         (50)         (49)                                   
      Adenoma                                          4 (8%)       2 (4%)       1 (2%)                                             
   Parathyroid Gland                                  (50)         (50)         (50)         (48)                                   
   Pituitary Gland                                    (50)         (50)         (50)         (50)                                   
      Pars Distalis, Adenoma                          16 (32%)     13 (26%)     12 (24%)     11 (22%)                               
      Pars Intermedia, Adenoma                         1 (2%)                                                                       
   Thyroid Gland                                      (50)         (50)         (50)         (49)                                   
      Bilateral, C-Cell, Adenoma                                    1 (2%)                                                          
      C-Cell, Adenoma                                  2 (4%)                    3 (6%)       2 (4%)                                
      C-Cell, Carcinoma                                             1 (2%)                                                          
      Follicular Cell, Adenoma                                      2 (4%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (49)         (49)         (49)         (48)                                   
   Preputial Gland                                    (50)         (47)         (49)         (48)                                   
      Adenoma                                          3 (6%)                    7 (14%)      2 (4%)                                
      Carcinoma                                        5 (10%)      2 (4%)                    1 (2%)                                
   Prostate                                           (50)         (48)         (50)         (49)                                   
   Seminal Vesicle                                    (50)         (47)         (50)         (48)                                   
   Testes                                             (49)         (49)         (49)         (48)                                   
      Bilateral, Interstitial Cell, Adenoma           33 (67%)     35 (71%)     37 (76%)     40 (83%)                               
      Interstitial Cell, Adenoma                       9 (18%)      8 (16%)      6 (12%)      3 (6%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    

                                                             Page   9                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (50)         (50)                                   
      Histiocytic Sarcoma                              1 (2%)                                                                       
      Melanoma Malignant, Metastatic, Skin                                       1 (2%)                                             
   Lymph Node                                         (20)         (25)         (20)         (23)                                   
   Lymph Node, Mandibular                             (50)         (50)         (50)         (50)                                   
   Lymph Node, Mesenteric                             (50)         (47)         (50)         (48)                                   
   Spleen                                             (49)         (48)         (50)         (49)                                   
   Thymus                                             (50)         (49)         (48)         (50)                                   
      Thymoma Benign                                                                          1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (49)         (48)         (50)         (49)                                   
      Carcinoma                                                     1 (2%)                                                          
      Fibroadenoma                                     4 (8%)       3 (6%)       6 (12%)      4 (8%)                                
   Skin                                               (50)         (50)         (50)         (50)                                   
      Basal Cell Adenoma                                                                      1 (2%)                                
      Keratoacanthoma                                  6 (12%)      4 (8%)       1 (2%)       5 (10%)                               
      Keratoacanthoma, Multiple                                                  1 (2%)                                             
      Squamous Cell Papilloma                          4 (8%)       1 (2%)       1 (2%)                                             
      Trichoepithelioma                                             1 (2%)                    1 (2%)                                
      Pinna, Melanoma Malignant                                                  1 (2%)       2 (4%)                                
      Subcutaneous Tissue, Fibroma                     4 (8%)       2 (4%)       4 (8%)                                             
      Subcutaneous Tissue, Lipoma                      1 (2%)                    1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Skeletal Muscle                                                 (1)                                                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (48)         (50)                                   
      Oligodendroglioma Malignant                                   1 (2%)                                                          
   Spinal Cord                                        (1)                                                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (50)         (50)         (50)         (50)                                   
      Alveolar/Bronchiolar Adenoma                     1 (2%)                                 4 (8%)                                
      Alveolar/Bronchiolar Carcinoma                                             2 (4%)                                             
      Carcinoma, Metastatic, Mammary Gland                          1 (2%)                                                          
      Carcinoma, Metastatic, Zymbal's Gland                         1 (2%)                                                          

                                                             Page  10                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - cont                                                                                                           
      Melanoma Malignant, Metastatic, Skin                                       1 (2%)                                             
      Osteosarcoma, Metastatic, Nose                   1 (2%)                                                                       
   Nose                                               (50)         (50)         (49)         (50)                                   
      Osteosarcoma                                     1 (2%)                                                                       
      Respiratory Epithelium, Squamous Cell                                                                                         
          Carcinoma                                                 1 (2%)                                                          
   Trachea                                            (50)         (50)         (50)         (50)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Zymbal's Gland                                     (1)          (1)          (1)          (1)                                    
      Carcinoma                                        1 (100%)     1 (100%)     1 (100%)     1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (48)         (50)         (49)                                   
      Mesenchymal Tumor Malignant                                   1 (2%)                                                          
      Renal Tubule, Adenoma                            1 (2%)                    1 (2%)       4 (8%)                                
      Renal Tubule, Adenoma, Multiple                                            1 (2%)       2 (4%)                                
      Renal Tubule, Carcinoma                                       1 (2%)                                                          
   Urinary Bladder                                    (50)         (47)         (50)         (49)                                   
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SYSTEMIC LESIONS                                                                                                                   

   Multiple Organs                                   *(50)        *(50)        *(50)        *(50)                                   
      Histiocytic Sarcoma                              1 (2%)                                                                       
      Leukemia Mononuclear                            29 (58%)     32 (64%)     26 (52%)     27 (54%)                               
      Lymphoma Malignant                                                                      1 (2%)                                
      Mesothelioma Benign                              1 (2%)                    1 (2%)                                             
      Mesothelioma Malignant                           1 (2%)       1 (2%)                                                          
____________________________________________________________________________________________________________________________________

                                                                                                                                    
     *   Number of animals with any tissue examined microscopically                                                                 

                                                             Page  11                                                               
NTP Experiment-Test: 55301-05  INCIDENCE RATES OF NEOPLASMS BY ANATOMIC SITE (SYSTEMIC LESIONS ABRIDGED) (a)      Report: PEIRPT05  
Study Type: CHRONIC                                              PYRIDINE                                         Date: 10/08/97    
Route: DOSED WATER                                                                                                Time: 11:55:09    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
         FISCHER 344 RATS MALE                     0 PPM        100 PPM      200 PPM      400 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
TUMOR SUMMARY                                                                                                                       
                                                                                                                                    
   Total Animals with Primary Neoplasms (b)            49          49          49          49                                       
     Total Primary Neoplasms                          151         120         133         123                                       
                                                                                                                                    
   Total Animals with Benign Neoplasms                 47          46          48          49                                       
     Total Benign Neoplasms                           112          77         102          89                                       
                                                                                                                                    
   Total Animals with Malignant Neoplasms              34          40          29          29                                       
     Total Malignant Neoplasms                         39          43          31          34                                       
                                                                                                                                    
   Total Animals with Metastatic Neoplasms              1           2           1                                                   
     Total Metastatic Neoplasm                          1           2           2                                                   
                                                                                                                                    
   Total Animals with Malignant Neoplasms                                                                                           
   Uncertain Primary Site                                                                                                           
                                                                                                                                    
   Total Animals with Neoplasms Uncertain-                                                                                          
   Benign or Malignant                                                                                                              
     Total Uncertain Neoplasms                                                                                                      
                                                                                                                                    

____________________________________________________________________________________________________________________________________
a  Number of animals examined microscopically at site and number of animals with lesion                                             
b  Primary tumors: all tumors except metastatic tumors                                                                              

                                                             Page  12                                                               
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