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TDMS Study 05185-03 Pathology Tables


                                     INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)
                                                       ISOBUTYL NITRITE (IBN)


NTP Experiment-Test: 05185-03                                                                                     Report: PEIRPT03
Study Type: CHRONIC                                                                                               Date: 05/20/95
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26




       Facility:  I. I. T. Research Institute

       Chemical CAS #:  542-56-3

       Lock Date:  05/22/92

       Cage Range:  All

       Reasons For Removal:    All

       Removal Date Range:     All

       Treatment Groups:       Include All
































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

                                                             Page   1

NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          56           56           56           56                                     
  Scheduled Sacrifice                                 10           10           10           10                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                13            4            7            6                                     
    Natural Death                                      4            6            8            7                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                29           35           30           33                                     
    Natural Death                                                                1                                                  
  Missing                                                           1                                                               
  Animals Examined Microscopically                    56           55           56           56                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Intestine Large, Colon                             (56)         (54)         (54)         (54)                                   
      Abscess                                                                                 1 (2%)                                
   Intestine Large, Cecum                             (56)         (54)         (53)         (53)                                   
      Inflammation                                     1 (2%)                                                                       
      Necrosis                                         1 (2%)                                                                       
   Intestine Small, Ileum                             (54)         (51)         (50)         (51)                                   
      Inflammation                                     1 (2%)                                                                       
   Liver                                              (56)         (54)         (56)         (56)                                   
      Angiectasis                                                   1 (2%)       2 (4%)                                             
      Basophilic Focus                                 7 (13%)      6 (11%)     15 (27%)      7 (13%)                               
      Basophilic Focus, Multiple                      22 (39%)     34 (63%)     30 (54%)     40 (71%)                               
      Clear Cell Focus                                 3 (5%)       1 (2%)       2 (4%)       2 (4%)                                
      Clear Cell Focus, Multiple                                                 1 (2%)       1 (2%)                                
      Congestion                                       1 (2%)                    3 (5%)       4 (7%)                                
      Developmental Malformation                       2 (4%)                                 2 (4%)                                
      Eosinophilic Focus                               1 (2%)       8 (15%)      5 (9%)       2 (4%)                                
      Eosinophilic Focus, Multiple                                               3 (5%)       1 (2%)                                
      Fatty Change                                    10 (18%)      4 (7%)       9 (16%)      4 (7%)                                
      Hematopoietic Cell Proliferation                 4 (7%)                                                                       
      Hemorrhage                                       1 (2%)                                 1 (2%)                                
      Hepatodiaphragmatic Nodule                       3 (5%)       3 (6%)       5 (9%)       6 (11%)                               
      Infiltration Cellular, Lymphocyte                             1 (2%)       1 (2%)       1 (2%)                                
      Inflammation                                     4 (7%)       3 (6%)       6 (11%)      2 (4%)                                
      Mixed Cell Focus                                 2 (4%)                    2 (4%)                                             
      Necrosis                                         3 (5%)       1 (2%)       1 (2%)       3 (5%)                                
      Pigmentation                                                               1 (2%)       1 (2%)                                
      Vacuolization Cytoplasmic                                                  4 (7%)                                             
      Centrilobular, Cytoplasmic Alteration                                      1 (2%)                                             
   Mesentery                                          (1)                       (4)          (2)                                    
      Fat, Necrosis                                    1 (100%)                  4 (100%)     2 (100%)                              
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    2                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
   Pancreas                                           (56)         (55)         (56)         (56)                                   
      Accessory Spleen                                 1 (2%)                    1 (2%)                                             
      Ectopic Liver                                                                           2 (4%)                                
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Acinar Cell, Atrophy                            19 (34%)     28 (51%)     26 (46%)     25 (45%)                               
   Salivary Glands                                    (56)         (55)         (55)         (56)                                   
      Inflammation                                                  1 (2%)                                                          
   Stomach, Forestomach                               (56)         (55)         (56)         (56)                                   
      Hyperplasia                                      2 (4%)                    3 (5%)       1 (2%)                                
      Inflammation                                                  1 (2%)       1 (2%)       1 (2%)                                
      Ulcer                                            3 (5%)                    2 (4%)                                             
      Ulcer, Multiple                                  2 (4%)                    1 (2%)                                             
   Stomach, Glandular                                 (56)         (54)         (55)         (56)                                   
      Inflammation                                     1 (2%)                    1 (2%)                                             
      Ulcer                                            2 (4%)                                 1 (2%)                                
      Ulcer, Multiple                                  1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (56)         (55)         (56)         (56)                                   
      Cardiomyopathy                                  38 (68%)     30 (55%)     34 (61%)     41 (73%)                               
      Atrium, Thrombosis                               2 (4%)                                 2 (4%)                                
      Endocardium, Proliferation                                                              1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (56)         (55)         (56)         (56)                                   
      Angiectasis                                      4 (7%)       7 (13%)     10 (18%)     10 (18%)                               
      Congestion                                                                 1 (2%)       1 (2%)                                
      Cyst                                             1 (2%)                                                                       
      Cytoplasmic Alteration                                        1 (2%)                                                          
      Degeneration                                     1 (2%)       2 (4%)       1 (2%)       1 (2%)                                
      Hemorrhage                                       1 (2%)       1 (2%)       1 (2%)       4 (7%)                                
      Hyperplasia                                      5 (9%)       5 (9%)                    3 (5%)                                
      Hypertrophy                                      1 (2%)       1 (2%)       1 (2%)       1 (2%)                                
      Infiltration Cellular, Lymphocyte                                                       1 (2%)                                
      Necrosis                                         1 (2%)                                                                       
      Vacuolization Cytoplasmic                        8 (14%)     13 (24%)      6 (11%)     10 (18%)                               
   Adrenal Medulla                                    (55)         (55)         (55)         (56)                                   
      Angiectasis                                      1 (2%)                                                                       
      Hyperplasia                                      2 (4%)       4 (7%)       3 (5%)       5 (9%)                                
   Pituitary Gland                                    (56)         (53)         (55)         (56)                                   
      Angiectasis                                                                             1 (2%)                                
      Congestion                                                                              1 (2%)                                
      Cyst                                             3 (5%)                    1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    3                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Hyperplasia                                      1 (2%)                                                                       
      Pars Distalis, Angiectasis                      11 (20%)     12 (23%)      5 (9%)       7 (13%)                               
      Pars Distalis, Cyst                             16 (29%)     21 (40%)     13 (24%)      9 (16%)                               
      Pars Distalis, Hyperplasia                       9 (16%)     24 (45%)     15 (27%)     21 (38%)                               
      Pars Nervosa, Developmental Malformation                      1 (2%)                                                          
   Thyroid Gland                                      (56)         (55)         (56)         (56)                                   
      C-Cell, Hyperplasia                              8 (14%)      4 (7%)       5 (9%)       6 (11%)                               
      Follicle, Dilatation                             1 (2%)                    1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Tissue NOS                                                      (1)                                                              
      Developmental Malformation                                    1 (100%)                                                        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (54)         (54)         (54)         (56)                                   
      Abscess                                                       1 (2%)       1 (2%)                                             
      Ectasia                                         32 (59%)     33 (61%)     38 (70%)     37 (66%)                               
      Hyperplasia                                      2 (4%)       4 (7%)       1 (2%)       6 (11%)                               
      Inflammation                                     2 (4%)       3 (6%)       5 (9%)       2 (4%)                                
   Ovary                                              (56)         (55)         (56)         (56)                                   
      Cyst                                             5 (9%)       9 (16%)      2 (4%)       2 (4%)                                
      Hemorrhage                                                                 1 (2%)                                             
      Bilateral, Cyst                                               1 (2%)       1 (2%)                                             
      Corpus Luteum, Hyperplasia                       1 (2%)                                                                       
   Uterus                                             (56)         (55)         (56)         (56)                                   
      Angiectasis                                                                             1 (2%)                                
      Cyst                                                          1 (2%)                    2 (4%)                                
      Dilatation                                       1 (2%)       2 (4%)       5 (9%)       2 (4%)                                
      Hemorrhage                                       1 (2%)                                                                       
      Prolapse                                                                   1 (2%)                                             
      Bilateral, Dilatation                            2 (4%)                                                                       
      Endometrium, Hyperplasia                         1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (56)         (55)         (56)         (56)                                   
      Atrophy                                                                    2 (4%)                                             
      Hyperplasia                                      7 (13%)      7 (13%)      6 (11%)      6 (11%)                               
      Myelofibrosis                                                 1 (2%)       1 (2%)       2 (4%)                                
   Lymph Node                                         (1)          (1)                       (3)                                    
      Axillary, Hyperplasia, Lymphoid                               1 (100%)                  1 (33%)                               
      Axillary, Hyperplasia, Plasma Cell                            1 (100%)                                                        
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    4                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Lumbar, Cyst                                     1 (100%)                                                                     
      Lumbar, Hyperplasia, Lymphoid                    1 (100%)                                                                     
      Lumbar, Pigmentation                             1 (100%)                               1 (33%)                               
   Lymph Node, Bronchial                              (36)         (40)         (46)         (38)                                   
      Hemorrhage                                      12 (33%)     23 (58%)     22 (48%)     20 (53%)                               
      Pigmentation                                     2 (6%)       7 (18%)      9 (20%)      7 (18%)                               
   Lymph Node, Mandibular                             (55)         (55)         (53)         (53)                                   
      Cyst                                                          1 (2%)                                                          
      Hemorrhage                                       2 (4%)       1 (2%)       2 (4%)       1 (2%)                                
      Hyperplasia, Lymphoid                                         1 (2%)       1 (2%)                                             
      Hyperplasia, Plasma Cell                         2 (4%)       3 (5%)                    1 (2%)                                
      Pigmentation                                                               2 (4%)                                             
   Lymph Node, Mesenteric                             (56)         (55)         (56)         (55)                                   
      Edema                                            1 (2%)                                                                       
      Hemorrhage                                       8 (14%)      8 (15%)      8 (14%)      8 (15%)                               
      Pigmentation                                     1 (2%)                                 1 (2%)                                
   Lymph Node, Mediastinal                            (54)         (54)         (51)         (53)                                   
      Hemorrhage                                      37 (69%)     41 (76%)     41 (80%)     35 (66%)                               
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Pigmentation                                    22 (41%)     31 (57%)     31 (61%)     17 (32%)                               
   Spleen                                             (56)         (55)         (54)         (56)                                   
      Congestion                                                                              1 (2%)                                
      Developmental Malformation                                                              1 (2%)                                
      Hematopoietic Cell Proliferation                 5 (9%)      11 (20%)      7 (13%)     10 (18%)                               
      Pigmentation                                     1 (2%)                    3 (6%)       3 (5%)                                
   Thymus                                             (54)         (53)         (55)         (54)                                   
      Atrophy                                         44 (81%)     26 (49%)     34 (62%)     24 (44%)                               
      Congestion                                                                 1 (2%)       1 (2%)                                
      Cyst                                                                                    1 (2%)                                
      Hemorrhage                                                    2 (4%)       4 (7%)       7 (13%)                               
      Necrosis                                                                   1 (2%)                                             
      Pigmentation                                     1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (56)         (55)         (56)         (56)                                   
      Abscess                                                       1 (2%)                                                          
      Galactocele                                                                             1 (2%)                                
      Hemorrhage                                                    1 (2%)                                                          
      Hyperplasia                                                                             1 (2%)                                
      Inflammation                                                                            2 (4%)                                
      Lactation                                       17 (30%)      7 (13%)      9 (16%)      8 (14%)                               
   Skin                                               (56)         (55)         (56)         (56)                                   
      Abscess                                                                                 1 (2%)                                
      Ulcer                                                         1 (2%)                                                          
      Ulcer, Multiple                                               1 (2%)                                                          
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    5                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
INTEGUMENTARY SYSTEM - CONT                                                                                                         
      Tail, Hyperkeratosis                             1 (2%)                                                                       
      Tail, Parakeratosis                              1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (56)         (55)         (56)         (56)                                   
      Femur, Hyperostosis                                           6 (11%)      2 (4%)       5 (9%)                                
      Turbinate, Hyperostosis                                       3 (5%)       2 (4%)       2 (4%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (56)         (55)         (56)         (56)                                   
      Compression                                     13 (23%)      8 (15%)     15 (27%)     10 (18%)                               
      Cyst                                                                                    1 (2%)                                
      Hemorrhage                                       2 (4%)                    5 (9%)       2 (4%)                                
      Hydrocephalus                                    3 (5%)                    1 (2%)       1 (2%)                                
      Necrosis                                                                   3 (5%)                                             
      Thrombosis                                       1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (56)         (55)         (56)         (56)                                   
      Foreign Body                                                                            1 (2%)                                
      Hemorrhage                                                                 1 (2%)                                             
      Infiltration Cellular, Lymphocyte                                                       3 (5%)                                
      Inflammation                                     3 (5%)                    4 (7%)       6 (11%)                               
      Metaplasia, Squamous                                                                    1 (2%)                                
      Epithelium, Hyperplasia                                                    2 (4%)       2 (4%)                                
   Lung                                               (56)         (55)         (56)         (56)                                   
      Congestion                                                    4 (7%)       6 (11%)      2 (4%)                                
      Hemorrhage                                      10 (18%)     15 (27%)     10 (18%)      9 (16%)                               
      Infiltration Cellular, Histiocyte                1 (2%)       1 (2%)       1 (2%)       2 (4%)                                
      Inflammation                                     4 (7%)       4 (7%)       3 (5%)       3 (5%)                                
      Alveolar Epithelium, Hyperplasia                 4 (7%)      12 (22%)     12 (21%)     35 (63%)                               
   Nose                                               (56)         (55)         (55)         (56)                                   
      Angiectasis                                                   1 (2%)       3 (5%)       1 (2%)                                
      Foreign Body                                     2 (4%)       1 (2%)                    1 (2%)                                
      Hemorrhage                                                    1 (2%)                    1 (2%)                                
      Inflammation                                     7 (13%)      5 (9%)       4 (7%)       7 (13%)                               
      Goblet Cell, Hyperplasia                         1 (2%)       4 (7%)       2 (4%)       3 (5%)                                
      Nasolacrimal Duct, Inflammation                  2 (4%)       2 (4%)                    2 (4%)                                
      Olfactory Epithelium, Cytoplasmic Alteration     2 (4%)                    3 (5%)       9 (16%)                               
      Respiratory Epithelium, Hyperplasia              3 (5%)       2 (4%)                    2 (4%)                                
   Trachea                                            (56)         (55)         (56)         (56)                                   
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    6                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS FEMALE                   CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Inflammation                                                  1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                             (1)          (1)                                                 
      Hemorrhage                                                    1 (100%)                                                        
      Bilateral, Lens, Cataract                                                  1 (100%)                                           
      Lens, Cataract                                                1 (100%)                                                        
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (56)         (55)         (56)         (56)                                   
      Angiectasis                                                                1 (2%)                                             
      Congestion                                                    1 (2%)       1 (2%)       1 (2%)                                
      Cyst                                             1 (2%)                                                                       
      Hypoplasia                                                    1 (2%)                                                          
      Infarct                                          1 (2%)                                                                       
      Mineralization                                  14 (25%)     16 (29%)     15 (27%)     17 (30%)                               
      Necrosis                                                                   1 (2%)                                             
      Nephropathy, Chronic                            52 (93%)     44 (80%)     43 (77%)     44 (79%)                               
      Pigmentation                                     3 (5%)                    4 (7%)       1 (2%)                                
      Transitional Epithelium, Hyperplasia             1 (2%)                                                                       
   Urinary Bladder                                    (56)         (54)         (55)         (52)                                   
      Dilatation                                       1 (2%)                    1 (2%)                                             
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Arteriole, Inflammation                                                                 1 (2%)                                
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    7                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
DISPOSITION SUMMARY                                                                                                                 
  Animals Initially In Study                          56           56           56           56                                     
  Scheduled Sacrifice                                 10           10           10           10                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                21           12            5            8                                     
    Natural Death                                      8           11            4           10                                     
    Accidently Killed                                                            1                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                17           23           36           28                                     
  Animals Examined Microscopically                    56           56           56           56                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (55)         (56)         (56)         (56)                                   
      Ectasia                                                       1 (2%)                                                          
   Intestine Large, Colon                             (55)         (55)         (56)         (55)                                   
      Infiltration Cellular, Lipocyte                                                         1 (2%)                                
   Intestine Large, Rectum                            (54)         (54)         (55)         (55)                                   
      Inflammation                                                                            1 (2%)                                
   Intestine Large, Cecum                             (54)         (51)         (54)         (53)                                   
      Inflammation                                                                            1 (2%)                                
   Intestine Small, Duodenum                          (54)         (54)         (56)         (55)                                   
      Ectopic Tissue                                                                          1 (2%)                                
      Hyperplasia                                                                             1 (2%)                                
      Inflammation                                                                            1 (2%)                                
   Intestine Small, Ileum                             (53)         (46)         (53)         (52)                                   
      Hemorrhage                                       1 (2%)                                                                       
      Hyperplasia, Lymphoid                                                      1 (2%)                                             
   Liver                                              (55)         (56)         (56)         (56)                                   
      Basophilic Focus                                 9 (16%)     11 (20%)      6 (11%)      7 (13%)                               
      Basophilic Focus, Multiple                       6 (11%)     11 (20%)     26 (46%)     22 (39%)                               
      Clear Cell Focus                                 3 (5%)       1 (2%)       8 (14%)      2 (4%)                                
      Clear Cell Focus, Multiple                       2 (4%)       9 (16%)      8 (14%)      3 (5%)                                
      Congestion                                       3 (5%)       2 (4%)                    7 (13%)                               
      Cytoplasmic Alteration                           1 (2%)                                                                       
      Degeneration, Cystic                             4 (7%)      12 (21%)     15 (27%)      4 (7%)                                
      Developmental Malformation                       1 (2%)                                                                       
      Eosinophilic Focus                               5 (9%)       7 (13%)      8 (14%)      2 (4%)                                
      Eosinophilic Focus, Multiple                     1 (2%)       4 (7%)      10 (18%)      4 (7%)                                
      Fatty Change                                     5 (9%)      12 (21%)      7 (13%)     14 (25%)                               
      Hemorrhage                                       2 (4%)       3 (5%)                                                          
      Hepatodiaphragmatic Nodule                       1 (2%)       2 (4%)                                                          
      Infiltration Cellular, Lymphocyte                                                       1 (2%)                                
      Inflammation                                     1 (2%)       1 (2%)       1 (2%)       1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    8                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Mixed Cell Focus                                 1 (2%)       4 (7%)       2 (4%)       4 (7%)                                
      Mixed Cell Focus, Multiple                       2 (4%)                    2 (4%)                                             
      Necrosis                                         2 (4%)       4 (7%)       2 (4%)       2 (4%)                                
      Pigmentation                                                  1 (2%)                                                          
      Bile Duct, Hyperplasia                           3 (5%)                    3 (5%)                                             
   Mesentery                                          (6)          (1)          (4)          (10)                                   
      Fat, Necrosis                                    6 (100%)     1 (100%)     4 (100%)     8 (80%)                               
   Pancreas                                           (55)         (56)         (56)         (56)                                   
      Ectopic Liver                                                              1 (2%)                                             
      Infiltration Cellular, Lymphocyte                2 (4%)                    1 (2%)                                             
      Inflammation                                                  1 (2%)                    2 (4%)                                
      Acinar Cell, Atrophy                            33 (60%)     32 (57%)     36 (64%)     32 (57%)                               
      Acinar Cell, Hyperplasia                         1 (2%)                                                                       
      Artery, Inflammation                                                       2 (4%)                                             
      Duct, Ectasia                                                 1 (2%)       1 (2%)                                             
   Pharynx                                                         (1)                                                              
      Palate, Hyperplasia, Squamous                                 1 (100%)                                                        
   Salivary Glands                                    (56)         (55)         (56)         (56)                                   
      Abscess                                                                                 1 (2%)                                
      Infiltration Cellular, Lymphocyte                                          1 (2%)                                             
   Stomach, Forestomach                               (55)         (56)         (56)         (56)                                   
      Hyperplasia                                      4 (7%)       3 (5%)       5 (9%)       3 (5%)                                
      Inflammation                                     1 (2%)       4 (7%)       3 (5%)       1 (2%)                                
      Ulcer                                            5 (9%)       3 (5%)       2 (4%)       3 (5%)                                
      Ulcer, Multiple                                               2 (4%)       2 (4%)                                             
   Stomach, Glandular                                 (55)         (56)         (56)         (55)                                   
      Hyperplasia                                                   1 (2%)                                                          
      Inflammation                                                  1 (2%)       1 (2%)       2 (4%)                                
      Necrosis                                         3 (5%)       3 (5%)                                                          
      Ulcer                                            1 (2%)                                 3 (5%)                                
      Ulcer, Multiple                                  2 (4%)       1 (2%)       1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (56)         (56)         (56)         (56)                                   
      Cardiomyopathy                                  42 (75%)     53 (95%)     55 (98%)     51 (91%)                               
      Inflammation                                                  2 (4%)                                                          
      Atrium, Dilatation                               1 (2%)                                 1 (2%)                                
      Atrium, Thrombosis                               2 (4%)       1 (2%)       2 (4%)       2 (4%)                                
      Valve, Inflammation                                           1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page    9                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (55)         (56)         (56)         (56)                                   
      Angiectasis                                                                1 (2%)                                             
      Congestion                                       1 (2%)                                 1 (2%)                                
      Cytoplasmic Alteration                           1 (2%)                                 1 (2%)                                
      Degeneration                                     3 (5%)       1 (2%)       1 (2%)       2 (4%)                                
      Hyperplasia                                      7 (13%)      4 (7%)       6 (11%)      3 (5%)                                
      Hypertrophy                                      1 (2%)       3 (5%)       2 (4%)       2 (4%)                                
      Vacuolization Cytoplasmic                        7 (13%)     19 (34%)     15 (27%)     16 (29%)                               
   Adrenal Medulla                                    (54)         (55)         (56)         (56)                                   
      Angiectasis                                      1 (2%)                                                                       
      Hyperplasia                                     15 (28%)     14 (25%)     19 (34%)     12 (21%)                               
   Islets, Pancreatic                                 (8)          (9)          (5)          (5)                                    
      Hyperplasia                                      4 (50%)      3 (33%)      2 (40%)      1 (20%)                               
   Parathyroid Gland                                  (49)         (50)         (48)         (52)                                   
      Hyperplasia                                      4 (8%)       6 (12%)      3 (6%)                                             
   Pituitary Gland                                    (55)         (56)         (56)         (55)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Pars Distalis, Angiectasis                       1 (2%)       7 (13%)      4 (7%)       4 (7%)                                
      Pars Distalis, Cyst                              2 (4%)       5 (9%)       4 (7%)       3 (5%)                                
      Pars Distalis, Hemorrhage                                     1 (2%)       1 (2%)                                             
      Pars Distalis, Hyperplasia                      11 (20%)     22 (39%)     25 (45%)     18 (33%)                               
      Pars Intermedia, Angiectasis                     1 (2%)                                                                       
      Pars Intermedia, Cyst                                         1 (2%)                                                          
   Thyroid Gland                                      (55)         (56)         (56)         (56)                                   
      C-Cell, Hyperplasia                              8 (15%)      5 (9%)       5 (9%)       3 (5%)                                
      Follicle, Dilatation                             4 (7%)                                                                       
      Follicular Cell, Hyperplasia                     1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (56)         (56)         (56)         (56)                                   
      Atrophy                                          1 (2%)                    1 (2%)                                             
      Granuloma Sperm                                  1 (2%)       2 (4%)       1 (2%)       1 (2%)                                
      Hypospermia                                     20 (36%)     26 (46%)     25 (45%)     29 (52%)                               
      Inflammation                                     2 (4%)                    2 (4%)                                             
      Inflammation, Chronic                            1 (2%)                                                                       
      Spermatocele                                     2 (4%)                                                                       
   Preputial Gland                                    (54)         (56)         (56)         (56)                                   
      Abscess                                          1 (2%)                                 1 (2%)                                
      Degeneration                                                               1 (2%)                                             
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   10                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
      Ectasia                                         43 (80%)     49 (88%)     49 (88%)     41 (73%)                               
      Hyperplasia                                                   1 (2%)       3 (5%)       1 (2%)                                
      Inflammation                                    11 (20%)      9 (16%)     12 (21%)     16 (29%)                               
   Prostate                                           (56)         (56)         (56)         (56)                                   
      Abscess                                          1 (2%)                                                                       
      Atrophy                                          1 (2%)                                                                       
      Concretion                                       6 (11%)      7 (13%)      7 (13%)     10 (18%)                               
      Congestion                                                                 1 (2%)                                             
      Hyperplasia                                      5 (9%)       4 (7%)       6 (11%)      4 (7%)                                
      Inflammation                                    32 (57%)     24 (43%)     23 (41%)     25 (45%)                               
      Vacuolization Cytoplasmic                                                               1 (2%)                                
      Epithelium, Cytoplasmic Alteration               1 (2%)       2 (4%)                                                          
   Seminal Vesicle                                    (55)         (56)         (56)         (56)                                   
      Depletion Cellular                              22 (40%)     23 (41%)     23 (41%)     31 (55%)                               
      Ectasia                                                       1 (2%)                    1 (2%)                                
      Inflammation                                     1 (2%)                                 2 (4%)                                
   Testes                                             (56)         (56)         (56)         (56)                                   
      Atrophy                                          8 (14%)      6 (11%)      6 (11%)      8 (14%)                               
      Degeneration                                                  1 (2%)                                                          
      Hypospermia                                                   1 (2%)                    1 (2%)                                
      Arteriole, Inflammation                          1 (2%)       6 (11%)     10 (18%)      5 (9%)                                
      Bilateral, Atrophy                              10 (18%)      2 (4%)       4 (7%)       7 (13%)                               
      Bilateral, Degeneration                                       1 (2%)                                                          
      Interstitial Cell, Hyperplasia                  16 (29%)     12 (21%)     12 (21%)     14 (25%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (55)         (55)         (56)         (56)                                   
      Congestion                                                                              1 (2%)                                
      Hemorrhage                                                                 1 (2%)                                             
      Hyperplasia                                     16 (29%)     15 (27%)      8 (14%)     15 (27%)                               
      Pigmentation                                                                            1 (2%)                                
   Lymph Node                                         (5)                                    (1)                                    
      Deep Cervical, Inflammation                                                             1 (100%)                              
      Lumbar, Hyperplasia, Plasma Cell                 1 (20%)                                                                      
      Renal, Hemorrhage                                                                       1 (100%)                              
   Lymph Node, Bronchial                              (47)         (43)         (40)         (39)                                   
      Hemorrhage                                      10 (21%)     18 (42%)     18 (45%)     18 (46%)                               
      Hyperplasia, Plasma Cell                         1 (2%)                                                                       
      Infiltration Cellular, Histiocyte                                                       1 (3%)                                
      Inflammation                                                  1 (2%)                                                          
      Pigmentation                                     1 (2%)       3 (7%)       2 (5%)       3 (8%)                                
   Lymph Node, Mandibular                             (55)         (55)         (56)         (56)                                   
      Cyst                                                          1 (2%)       2 (4%)                                             
      Hemorrhage                                       6 (11%)      4 (7%)       7 (13%)      3 (5%)                                
      Hyperplasia, Lymphoid                                         1 (2%)                    1 (2%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   11                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Hyperplasia, Plasma Cell                         3 (5%)       7 (13%)      6 (11%)      4 (7%)                                
      Infiltration Cellular, Histiocyte                                          1 (2%)                                             
      Pigmentation                                                  1 (2%)                    1 (2%)                                
   Lymph Node, Mesenteric                             (55)         (56)         (56)         (54)                                   
      Hemorrhage                                       4 (7%)      12 (21%)      5 (9%)       7 (13%)                               
   Lymph Node, Mediastinal                            (55)         (52)         (52)         (55)                                   
      Depletion Lymphoid                                                                      1 (2%)                                
      Hemorrhage                                      22 (40%)     36 (69%)     33 (63%)     36 (65%)                               
      Hyperplasia, Lymphoid                                                      1 (2%)                                             
      Hyperplasia, Plasma Cell                         3 (5%)       2 (4%)                    2 (4%)                                
      Infiltration Cellular, Histiocyte                                          1 (2%)       1 (2%)                                
      Pigmentation                                     5 (9%)      14 (27%)     13 (25%)     12 (22%)                               
   Spleen                                             (56)         (55)         (56)         (55)                                   
      Congestion                                       1 (2%)       2 (4%)                    1 (2%)                                
      Degeneration, Cystic                                                       2 (4%)       5 (9%)                                
      Developmental Malformation                                                              1 (2%)                                
      Fibrosis                                                      1 (2%)       2 (4%)                                             
      Hematopoietic Cell Proliferation                 4 (7%)       6 (11%)      5 (9%)      13 (24%)                               
      Hemorrhage                                                                 1 (2%)                                             
      Inflammation                                                                            1 (2%)                                
      Necrosis                                                                                1 (2%)                                
      Capsule, Fibrosis                                             1 (2%)                                                          
   Thymus                                             (51)         (56)         (55)         (54)                                   
      Atrophy                                         35 (69%)     43 (77%)     42 (76%)     41 (76%)                               
      Congestion                                                                              2 (4%)                                
      Cyst                                                                                    1 (2%)                                
      Hemorrhage                                       3 (6%)       8 (14%)      2 (4%)       3 (6%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (52)         (53)         (56)         (53)                                   
      Galactocele                                      1 (2%)       2 (4%)                    4 (8%)                                
      Hyperplasia                                      1 (2%)                                 1 (2%)                                
      Inflammation                                     1 (2%)                                 1 (2%)                                
      Lactation                                       13 (25%)     18 (34%)     10 (18%)     16 (30%)                               
      Pigmentation                                     2 (4%)       1 (2%)                                                          
   Skin                                               (56)         (56)         (56)         (56)                                   
      Inflammation                                     1 (2%)                                                                       
      Pinna, Parakeratosis                                          1 (2%)                                                          
      Subcutaneous Tissue, Abscess                                  1 (2%)                    1 (2%)                                
      Tail, Hyperkeratosis                                                                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   12                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (56)         (56)         (56)         (56)                                   
      Calvarium, Hemorrhage                                         1 (2%)                                                          
      Coccygeal, Fracture                                           1 (2%)                                                          
      Cranium, Hemorrhage                              1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (56)         (56)         (56)         (56)                                   
      Compression                                      9 (16%)     17 (30%)      6 (11%)     22 (39%)                               
      Hemorrhage                                       2 (4%)       2 (4%)       1 (2%)       1 (2%)                                
      Hydrocephalus                                    4 (7%)       3 (5%)       1 (2%)       2 (4%)                                
      Infiltration Cellular, Lymphocyte                             1 (2%)                                                          
      Necrosis                                                                   1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (56)         (56)         (56)         (56)                                   
      Foreign Body                                     1 (2%)                                 1 (2%)                                
      Infiltration Cellular, Lymphocyte                3 (5%)                    1 (2%)       2 (4%)                                
      Inflammation                                     3 (5%)       2 (4%)       4 (7%)       4 (7%)                                
      Epithelium, Hyperplasia                          1 (2%)       1 (2%)       1 (2%)       1 (2%)                                
   Lung                                               (56)         (56)         (56)         (56)                                   
      Congestion                                       4 (7%)       5 (9%)       3 (5%)       3 (5%)                                
      Hemorrhage                                       9 (16%)     15 (27%)      4 (7%)       3 (5%)                                
      Infiltration Cellular, Histiocyte                             1 (2%)                    1 (2%)                                
      Inflammation                                     3 (5%)       8 (14%)      3 (5%)       6 (11%)                               
      Leukocytosis                                     1 (2%)       1 (2%)                                                          
      Necrosis                                                      1 (2%)                                                          
      Alveolar Epithelium, Hyperplasia                 5 (9%)      11 (20%)     28 (50%)     38 (68%)                               
      Arteriole, Inflammation                                                    1 (2%)                                             
      Artery, Inflammation                                                       1 (2%)                                             
      Artery, Thrombosis                                            1 (2%)       1 (2%)                                             
      Bronchus, Hyperplasia                            1 (2%)                                                                       
      Goblet Cell, Hyperplasia                                      1 (2%)                                                          
   Nose                                               (55)         (55)         (56)         (56)                                   
      Angiectasis                                      7 (13%)      4 (7%)       1 (2%)       2 (4%)                                
      Foreign Body                                     6 (11%)      3 (5%)       3 (5%)       2 (4%)                                
      Hemorrhage                                       5 (9%)                    2 (4%)       1 (2%)                                
      Infiltration Cellular, Lymphocyte                                                       2 (4%)                                
      Inflammation                                     9 (16%)     10 (18%)      7 (13%)     11 (20%)                               
      Polyp Inflammatory                               1 (2%)                                                                       
      Goblet Cell, Hyperplasia                                      3 (5%)       3 (5%)       1 (2%)                                
      Nasolacrimal Duct, Inflammation                               3 (5%)                    2 (4%)                                
      Olfactory Epithelium, Cytoplasmic Alteration                  3 (5%)       2 (4%)       5 (9%)                                
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   13                                                              
NTP Experiment-Test: 05185-03         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                       ISOBUTYL NITRITE (IBN)                                  Date: 05/20/95  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 10:47:26  
____________________________________________________________________________________________________________________________________
         FISCHER 344 RATS MALE                     CONTROL      37.5 PPM     75 PPM       150 PPM                                   
                                                                                                                                    
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Respiratory Epithelium, Hyperplasia              2 (4%)       3 (5%)       4 (7%)       4 (7%)                                
      Respiratory Epithelium, Metaplasia, Squamous                  2 (4%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)                       (1)                                                 
      Hemorrhage                                                                 1 (100%)                                           
      Inflammation                                                               1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (55)         (55)         (56)         (56)                                   
      Congestion                                       1 (2%)                                 1 (2%)                                
      Cyst                                             1 (2%)       1 (2%)                    3 (5%)                                
      Hydronephrosis                                   1 (2%)                                                                       
      Inflammation                                                  1 (2%)                                                          
      Nephropathy, Chronic                            49 (89%)     52 (95%)     55 (98%)     55 (98%)                               
      Pigmentation                                     3 (5%)       2 (4%)                    5 (9%)                                
      Pelvis, Hyperplasia                              1 (2%)                                                                       
      Renal Tubule, Cytoplasmic Alteration             1 (2%)                                                                       
   Urinary Bladder                                    (56)         (55)         (56)         (55)                                   
      Calculus Micro Observation Only                  1 (2%)                                                                       
      Dilatation                                       4 (7%)       1 (2%)                    1 (2%)                                
      Infiltration Cellular, Lymphocyte                                                       1 (2%)                                
      Inflammation                                     1 (2%)       1 (2%)                                                          
      Transitional Epithelium, Hyperplasia             1 (2%)                                                                       
                                                                                                                                    
a  Number of animals examined microscopically at site and number of animals with lesion                                             
                                                             Page   14                                                              
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------