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TDMS Study 88050-06 Pathology Tables

NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99
Route: GAVAGE                                                                                                     Time: 08:32:57

                                                    FINAL#1, CORE STUDY MICE




       Facility:  Battelle Columbus Laboratory

       Chemical CAS #:  126-98-7

       Lock Date:  06/26/98

       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: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 


  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                     14           13            4            7                                     
    Moribund Sacrifice                                 1            2            3            3                                     
    Accidently Killed                                                                        15                                     
  Survivors                                                                                                                         
    Natural Death                                      1                                                                            
    Terminal Sacrifice                                34           35           43           25                                     

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (50)         (50)         (50)         (50)                                   
      Periesophageal Tissue, Inflammation, Chronic                                                                                  
          Active                                       1 (2%)                                                                       
   Gallbladder                                        (50)         (50)         (50)         (48)                                   
      Cyst                                             1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell                                    1 (2%)                                             
   Intestine Small, Duodenum                          (49)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Metaplasia, Squamous                                                       1 (2%)                                             
      Epithelium, Ulcer                                1 (2%)                                                                       
   Intestine Small, Jejunum                           (50)         (50)         (50)         (50)                                   
      Ulcer                                                         1 (2%)                                                          
      Epithelium, Inflammation, Suppurative                         1 (2%)                                                          
      Peyer's Patch, Hyperplasia, Lymphoid                                                    2 (4%)                                
   Liver                                              (50)         (50)         (49)         (50)                                   
      Angiectasis                                                   1 (2%)       1 (2%)                                             
      Basophilic Focus                                 1 (2%)       7 (14%)      2 (4%)       2 (4%)                                
      Clear Cell Focus                                 3 (6%)       6 (12%)      6 (12%)      1 (2%)                                
      Eosinophilic Focus                               9 (18%)      3 (6%)      11 (22%)      3 (6%)                                
      Hematopoietic Cell Proliferation                 2 (4%)       2 (4%)       6 (12%)      2 (4%)                                
      Hepatodiaphragmatic Nodule                                    1 (2%)                                                          
      Infiltration Cellular, Mononuclear Cell         30 (60%)     36 (72%)     40 (82%)     30 (60%)                               
      Inflammation, Chronic Active                    32 (64%)     36 (72%)     41 (84%)     38 (76%)                               
      Mineralization                                                             1 (2%)       1 (2%)                                
      Mixed Cell Focus                                 3 (6%)       1 (2%)       3 (6%)                                             
      Necrosis                                         3 (6%)       2 (4%)       2 (4%)       1 (2%)                                
      Pigmentation                                    18 (36%)     12 (24%)     17 (35%)      7 (14%)                               
      Tension Lipidosis                                2 (4%)       3 (6%)                                                          
      Hepatocyte, Vacuolization Cytoplasmic            7 (14%)      9 (18%)      3 (6%)      18 (36%)                               
   Mesentery                                          (16)         (11)         (15)         (4)                                    
      Fibrosis                                         8 (50%)      7 (64%)     10 (67%)      2 (50%)                               
      Hemorrhage                                                    1 (9%)                                                          

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Inflammation, Chronic Active                     5 (31%)      6 (55%)      8 (53%)                                            
      Mineralization                                   5 (31%)      7 (64%)     12 (80%)      1 (25%)                               
      Pigmentation                                                               1 (7%)                                             
      Thrombosis                                                                 1 (7%)                                             
      Fat, Necrosis                                    8 (50%)      7 (64%)     11 (73%)      3 (75%)                               
   Oral Mucosa                                        (3)          (5)          (2)          (1)                                    
      Gingival, Foreign Body                           2 (67%)      5 (100%)     1 (50%)                                            
      Gingival, Inflammation, Chronic Active           2 (67%)      5 (100%)     2 (100%)                                           
      Pharyngeal, Foreign Body                         1 (33%)                                                                      
   Pancreas                                           (50)         (50)         (50)         (48)                                   
      Cyst                                                                       1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell                                                 2 (4%)                                
      Acinus, Atrophy                                  1 (2%)                                                                       
      Acinus, Hyperplasia                                                                     1 (2%)                                
   Salivary Glands                                    (48)         (50)         (50)         (49)                                   
      Infiltration Cellular, Mononuclear Cell         27 (56%)     29 (58%)     32 (64%)     27 (55%)                               
      Inflammation, Chronic Active                                               2 (4%)       1 (2%)                                
      Mineralization                                                             1 (2%)                                             
   Stomach, Forestomach                               (50)         (50)         (50)         (50)                                   
      Diverticulum                                     1 (2%)                                                                       
      Hyperkeratosis                                                1 (2%)                                                          
      Epithelium, Hyperplasia                          3 (6%)       2 (4%)       1 (2%)       1 (2%)                                
      Epithelium, Inflammation, Chronic Active         1 (2%)       2 (4%)       2 (4%)       1 (2%)                                
      Epithelium, Ulcer                                1 (2%)       1 (2%)       1 (2%)                                             
   Stomach, Glandular                                 (50)         (50)         (50)         (50)                                   
      Ectopic Tissue                                                1 (2%)                                                          
      Mineralization                                   1 (2%)       1 (2%)                    1 (2%)                                
      Epithelium, Dysplasia                                         1 (2%)                                                          
      Epithelium, Erosion                              1 (2%)                                                                       
      Glands, Ectasia                                 16 (32%)      9 (18%)     10 (20%)      3 (6%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (49)         (50)         (50)         (50)                                   
      Aorta, Mineralization                            1 (2%)                                                                       
   Heart                                              (50)         (50)         (50)         (50)                                   
      Inflammation, Suppurative                                                               1 (2%)                                
      Mineralization                                   1 (2%)                                                                       
      Artery, Mineralization                           1 (2%)                                                                       
      Valve, Inflammation, Chronic Active                           1 (2%)                                                          
      Valve, Inflammation, Suppurative                 1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (49)         (50)         (50)         (50)                                   
      Accessory Adrenal Cortical Nodule                                                       2 (4%)                                
      Hematopoietic Cell Proliferation                              1 (2%)                    1 (2%)                                
      Hypertrophy                                      1 (2%)                    1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell                       1 (2%)                                                          
      Capsule, Hyperplasia                            48 (98%)     48 (96%)     50 (100%)    50 (100%)                              
      Zona Reticularis, Hyperplasia                                              1 (2%)                                             
   Adrenal Medulla                                    (49)         (50)         (50)         (50)                                   
      Hyperplasia                                      1 (2%)                                 1 (2%)                                
   Islets, Pancreatic                                 (50)         (50)         (50)         (49)                                   
      Hyperplasia                                     41 (82%)     37 (74%)     40 (80%)     33 (67%)                               
   Pituitary Gland                                    (49)         (49)         (49)         (49)                                   
      Pars Distalis, Angiectasis                       2 (4%)       3 (6%)       6 (12%)      2 (4%)                                
      Pars Distalis, Cyst                              1 (2%)                    2 (4%)       2 (4%)                                
      Pars Distalis, Hemorrhage                                     1 (2%)                                                          
      Pars Distalis, Hyperplasia                       9 (18%)     12 (24%)     10 (20%)     11 (22%)                               
      Pars Distalis, Pigmentation                                                1 (2%)                                             
   Thyroid Gland                                      (49)         (50)         (50)         (50)                                   
      Ectopic Thymus                                                             1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell          1 (2%)                                 1 (2%)                                
      Inflammation, Chronic Active                     1 (2%)                                                                       
      C-Cell, Hyperplasia                                           1 (2%)                                                          
      Follicle, Cyst                                   5 (10%)      3 (6%)       3 (6%)       4 (8%)                                
      Follicular Cell, Hyperplasia                     1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Clitoral Gland                                     (50)         (50)         (50)         (49)                                   
      Infiltration Cellular, Mononuclear Cell          4 (8%)       2 (4%)       3 (6%)       1 (2%)                                
      Inflammation, Chronic Active                     2 (4%)       1 (2%)                    1 (2%)                                
      Pigmentation                                                  1 (2%)                                                          
      Duct, Cyst                                                                 2 (4%)       2 (4%)                                
   Ovary                                              (50)         (50)         (50)         (49)                                   
      Angiectasis                                                   1 (2%)                                                          
      Cyst                                            17 (34%)     14 (28%)     18 (36%)     10 (20%)                               
      Hemorrhage                                                    1 (2%)       4 (8%)       1 (2%)                                
      Inflammation, Suppurative                                                               1 (2%)                                
      Mineralization                                   2 (4%)       3 (6%)       2 (4%)       1 (2%)                                
      Pigmentation                                     7 (14%)     16 (32%)     11 (22%)      6 (12%)                               
      Thrombosis                                                    1 (2%)       3 (6%)                                             

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
   Uterus                                             (50)         (50)         (50)         (50)                                   
      Angiectasis                                                                             1 (2%)                                
      Hemorrhage                                                                              1 (2%)                                
      Hydrometra                                      23 (46%)     28 (56%)     31 (62%)     20 (40%)                               
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Inflammation, Suppurative                                     1 (2%)                                                          
      Pigmentation                                                  1 (2%)                                                          
      Thrombosis                                       1 (2%)                                                                       
      Endometrium, Hyperplasia                         1 (2%)                                                                       
      Endometrium, Hyperplasia, Cystic                27 (54%)     24 (48%)     24 (48%)     32 (64%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (50)         (50)                                   
      Hyperplasia                                      2 (4%)       2 (4%)       4 (8%)       1 (2%)                                
      Myelofibrosis                                    2 (4%)       3 (6%)                                                          
   Lymph Node                                         (9)          (6)          (8)          (5)                                    
      Lumbar, Ectasia                                               1 (17%)                   1 (20%)                               
      Lumbar, Hyperplasia, Lymphoid                                              1 (13%)                                            
      Mediastinal, Hyperplasia, Lymphoid               1 (11%)                   2 (25%)                                            
      Mediastinal, Infiltration Cellular,                                                                                           
          Histiocyte                                   1 (11%)                                                                      
      Mediastinal, Inflammation                                                               1 (20%)                               
      Pancreatic, Fibrosis                             1 (11%)                                                                      
      Pancreatic, Hyperplasia, Lymphoid                1 (11%)                                                                      
      Pancreatic, Pigmentation                         1 (11%)                                                                      
   Lymph Node, Mandibular                             (48)         (49)         (46)         (47)                                   
      Hyperplasia, Lymphoid                            5 (10%)      4 (8%)       3 (7%)       1 (2%)                                
      Infiltration Cellular, Plasma Cell               1 (2%)                                                                       
      Pigmentation                                     3 (6%)      16 (33%)      9 (20%)      4 (9%)                                
   Lymph Node, Mesenteric                             (47)         (48)         (47)         (46)                                   
      Ectasia                                          2 (4%)                                                                       
      Hemorrhage                                       2 (4%)       1 (2%)                                                          
      Hyperplasia, Lymphoid                            2 (4%)                    1 (2%)       1 (2%)                                
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Pigmentation                                     1 (2%)                                                                       
   Spleen                                             (50)         (50)         (49)         (49)                                   
      Hematopoietic Cell Proliferation                18 (36%)     22 (44%)     15 (31%)     10 (20%)                               
      Hyperplasia, Lymphoid                            1 (2%)       3 (6%)       1 (2%)                                             
      Mineralization                                                             1 (2%)                                             
      Necrosis                                                      1 (2%)                                                          
      Pigmentation                                                               1 (2%)                                             
   Thymus                                             (47)         (43)         (46)         (48)                                   
      Cyst                                            20 (43%)     17 (40%)     23 (50%)     19 (40%)                               
      Ectopic Parathyroid Gland                        1 (2%)       1 (2%)       1 (2%)                                             
      Hyperplasia, Lymphoid                                                      2 (4%)                                             

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Thymocyte, Necrosis                                           1 (2%)                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (49)         (50)         (49)         (49)                                   
      Hyperplasia, Cystic                              3 (6%)       1 (2%)                                                          
   Skin                                               (50)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Epidermis, Ulcer                                 1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Osteosclerosis                                   1 (2%)                                                                       
   Skeletal Muscle                                    (4)          (1)          (2)                                                 
      Infiltration Cellular, Mononuclear Cell          1 (25%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (50)         (50)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Infiltration Cellular, Mononuclear Cell          2 (4%)                                                                       
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Meninges, Hemorrhage                                          1 (2%)                                                          
   Peripheral Nerve                                   (1)                       (1)                                                 
      Sciatic, Axon, Degeneration                      1 (100%)                                                                     
   Spinal Cord                                        (1)                       (2)                                                 
      Demyelination                                    1 (100%)                  1 (50%)                                            
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (50)         (50)         (50)         (50)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Inflammation, Chronic Active                     2 (4%)       1 (2%)       3 (6%)       1 (2%)                                
      Mineralization                                   5 (10%)      1 (2%)       2 (4%)       2 (4%)                                
      Necrosis                                                                                1 (2%)                                
      Pigmentation                                     1 (2%)                                                                       
      Thrombosis                                                    1 (2%)       1 (2%)                                             
      Alveolar Epithelium, Hyperplasia                 1 (2%)       1 (2%)       1 (2%)                                             
      Alveolus, Infiltration Cellular, Histiocyte      1 (2%)                                 2 (4%)                                
      Artery, Mediastinum, Mineralization              1 (2%)                                                                       
      Mediastinum, Mineralization                                   1 (2%)                                                          
   Nose                                               (50)         (50)         (50)         (50)                                   

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Inflammation, Suppurative                        1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (2)          (1)                       (4)                                    
      Atrophy                                          1 (50%)      1 (100%)                  1 (25%)                               
      Anterior Chamber, Infiltration Cellular,                                                                                      
           Polymorphonuclear                                                                  1 (25%)                               
      Cornea, Inflammation, Chronic Active                                                    1 (25%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (49)         (50)                                   
      Accumulation, Hyaline Droplet                    2 (4%)       1 (2%)                                                          
      Hydronephrosis                                                             1 (2%)                                             
      Infarct, Multiple                                1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell         35 (70%)     42 (84%)     44 (90%)     35 (70%)                               
      Inflammation, Chronic Active                     1 (2%)       1 (2%)                                                          
      Mineralization                                   5 (10%)      5 (10%)      5 (10%)      6 (12%)                               
      Nephropathy                                     15 (30%)     19 (38%)     22 (45%)      9 (18%)                               
      Pigmentation                                                               1 (2%)                                             
      Capsule, Mineralization                          1 (2%)                                                                       
      Cortex, Cyst                                     2 (4%)       3 (6%)       1 (2%)       1 (2%)                                
      Papilla, Inflammation, Acute                     1 (2%)                                                                       
      Renal Tubule, Casts Protein                                                1 (2%)                                             
   Urinary Bladder                                    (50)         (50)         (50)         (50)                                   
      Infiltration Cellular, Mononuclear Cell         28 (56%)     31 (62%)     29 (58%)     22 (44%)                               
      Inflammation, Chronic Active                     1 (2%)                                                                       
      Pigmentation                                     1 (2%)                                                                       
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 


  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                      9            5            4            3                                     
    Moribund Sacrifice                                 5            2            3                                                  
    Dosing Accident                                                                           1                                     
    Accidently Killed                                                                        24                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                34           43           41           22                                     
    Natural Death                                      1                         2                                                  
  Missing                                              1                                                                            

  Animals Examined Microscopically                    49           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (49)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                                                            1 (2%)                                
      Periesophageal Tissue, Inflammation, Chronic                                                                                  
          Active                                                    1 (2%)                                                          
   Intestine Small, Duodenum                          (49)         (49)         (50)         (50)                                   
      Ectasia                                                                    1 (2%)                                             
      Hyperplasia                                                   3 (6%)       1 (2%)       1 (2%)                                
   Intestine Small, Jejunum                           (49)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Peyer's Patch, Hyperplasia, Lymphoid                                       1 (2%)       1 (2%)                                
   Intestine Small, Ileum                             (49)         (50)         (50)         (49)                                   
      Inflammation, Chronic Active                     1 (2%)       1 (2%)                                                          
   Liver                                              (49)         (50)         (50)         (50)                                   
      Angiectasis                                      1 (2%)                    1 (2%)                                             
      Basophilic Focus                                              4 (8%)       6 (12%)      2 (4%)                                
      Clear Cell Focus                                 7 (14%)     10 (20%)     10 (20%)      4 (8%)                                
      Eosinophilic Focus                              16 (33%)     10 (20%)     12 (24%)      3 (6%)                                
      Fibrosis                                                                   1 (2%)                                             
      Hematopoietic Cell Proliferation                                           3 (6%)       1 (2%)                                
      Hepatodiaphragmatic Nodule                       1 (2%)                                                                       
      Infiltration Cellular, Mast Cell                 1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell          9 (18%)     11 (22%)      7 (14%)      6 (12%)                               
      Inflammation, Chronic Active                    22 (45%)     21 (42%)     19 (38%)     21 (42%)                               
      Inflammation, Granulomatous                                                1 (2%)                                             
      Malformation                                     1 (2%)                                                                       
      Mineralization                                                             1 (2%)                                             
      Mixed Cell Focus                                             11 (22%)     11 (22%)      2 (4%)                                
      Necrosis                                         6 (12%)      5 (10%)      1 (2%)                                             
      Pigmentation                                     3 (6%)                    2 (4%)       3 (6%)                                
      Tension Lipidosis                                1 (2%)                    1 (2%)                                             

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Bile Duct, Cyst                                                            1 (2%)       1 (2%)                                
      Bile Duct, Hyperplasia                                                                  1 (2%)                                
      Hepatocyte, Vacuolization Cytoplasmic            6 (12%)     10 (20%)      9 (18%)     16 (32%)                               
      Hepatocyte, Portal, Hypertrophy                                            1 (2%)                                             
      Hepatocyte, Centrilobular, Degeneration                                    1 (2%)                                             
   Mesentery                                          (3)          (6)          (6)          (1)                                    
      Fibrosis                                         1 (33%)      1 (17%)                                                         
      Inflammation, Chronic Active                     1 (33%)      1 (17%)      1 (17%)      1 (100%)                              
      Inflammation, Granulomatous                                                2 (33%)                                            
      Mineralization                                                1 (17%)      1 (17%)                                            
      Thrombosis                                       1 (33%)                                                                      
      Fat, Necrosis                                    1 (33%)      2 (33%)      1 (17%)                                            
   Oral Mucosa                                        (31)         (30)         (27)         (10)                                   
      Gingival, Foreign Body                          27 (87%)     29 (97%)     26 (96%)     10 (100%)                              
      Gingival, Inflammation, Acute                    9 (29%)      3 (10%)     10 (37%)      6 (60%)                               
      Gingival, Inflammation, Chronic                               1 (3%)                                                          
      Gingival, Inflammation, Chronic Active          19 (61%)     26 (87%)     16 (59%)      2 (20%)                               
   Pancreas                                           (49)         (50)         (50)         (50)                                   
      Infiltration Cellular, Mononuclear Cell          1 (2%)       1 (2%)                    1 (2%)                                
      Artery, Mineralization                                                                  1 (2%)                                
   Salivary Glands                                    (49)         (50)         (50)         (50)                                   
      Granuloma                                        1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell         22 (45%)     35 (70%)     36 (72%)     29 (58%)                               
      Inflammation, Chronic                            1 (2%)                                                                       
      Inflammation, Chronic Active                                               1 (2%)                                             
      Mineralization                                   1 (2%)       1 (2%)       1 (2%)                                             
   Stomach, Forestomach                               (49)         (50)         (50)         (50)                                   
      Cyst, Squamous                                                             1 (2%)                                             
      Epithelium, Hyperplasia                          2 (4%)       3 (6%)       1 (2%)       1 (2%)                                
      Epithelium, Inflammation, Chronic Active         2 (4%)       1 (2%)       2 (4%)                                             
      Epithelium, Ulcer                                1 (2%)       1 (2%)                                                          
   Stomach, Glandular                                 (49)         (50)         (50)         (50)                                   
      Hyperplasia                                                   1 (2%)                                                          
      Mineralization                                                1 (2%)                    2 (4%)                                
      Ulcer                                            1 (2%)                                                                       
      Epithelium, Erosion                              1 (2%)                                                                       
      Epithelium, Hyperplasia                                       1 (2%)       1 (2%)                                             
      Epithelium, Inflammation, Chronic Active         1 (2%)       1 (2%)       1 (2%)                                             
      Glands, Ectasia                                 17 (35%)     10 (20%)     20 (40%)      5 (10%)                               
      Serosa, Inflammation, Granulomatous                                        1 (2%)                                             
   Tooth                                              (6)                       (1)          (2)                                    
      Malformation                                     6 (100%)                  1 (100%)     2 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (48)         (50)         (50)         (50)                                   
      Inflammation, Chronic Active                     2 (4%)       1 (2%)                    1 (2%)                                
      Mineralization                                   2 (4%)                    1 (2%)       1 (2%)                                
      Artery, Inflammation, Chronic Active                          1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (49)         (50)         (50)         (50)                                   
      Degeneration, Fatty                              1 (2%)                                                                       
      Hematopoietic Cell Proliferation                                           1 (2%)                                             
      Hyperplasia                                     14 (29%)     12 (24%)     16 (32%)      7 (14%)                               
      Hypertrophy                                     26 (53%)     34 (68%)     28 (56%)     15 (30%)                               
      Inflammation, Suppurative                                     1 (2%)                                                          
      Metaplasia, Osseous                              1 (2%)                                                                       
      Capsule, Hyperplasia                            41 (84%)     41 (82%)     40 (80%)     45 (90%)                               
   Adrenal Medulla                                    (49)         (50)         (50)         (50)                                   
      Hematopoietic Cell Proliferation                                           1 (2%)                                             
      Hyperplasia                                      1 (2%)                                                                       
   Islets, Pancreatic                                 (49)         (50)         (50)         (50)                                   
      Hyperplasia                                     47 (96%)     43 (86%)     48 (96%)     46 (92%)                               
   Parathyroid Gland                                  (42)         (35)         (39)         (38)                                   
      Cyst                                             1 (2%)       2 (6%)       1 (3%)       1 (3%)                                
   Pituitary Gland                                    (48)         (49)         (49)         (46)                                   
      Atypia Cellular                                                                         1 (2%)                                
      Pars Distalis, Cyst                              1 (2%)       2 (4%)       5 (10%)      3 (7%)                                
      Pars Distalis, Hyperplasia                       2 (4%)       2 (4%)                                                          
   Thyroid Gland                                      (49)         (50)         (50)         (50)                                   
      Follicle, Cyst                                   2 (4%)       2 (4%)       2 (4%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Coagulating Gland                                                            (1)          (2)                                    
      Inflammation, Suppurative                                                  1 (100%)                                           
   Epididymis                                         (49)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                                                       
      Granuloma Sperm                                  2 (4%)                    1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell         17 (35%)     26 (52%)     30 (60%)     21 (42%)                               
      Inflammation, Chronic Active                     1 (2%)       1 (2%)                    1 (2%)                                
      Mineralization                                   2 (4%)                    1 (2%)                                             

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
GENITAL SYSTEM - CONT                                                                                                               
   Penis                                              (1)                                                                           
      Hemorrhage                                       1 (100%)                                                                     
   Preputial Gland                                    (49)         (50)         (50)         (49)                                   
      Atrophy                                          1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell         21 (43%)     25 (50%)     27 (54%)     26 (53%)                               
      Inflammation, Chronic Active                    13 (27%)      6 (12%)      7 (14%)      3 (6%)                                
      Duct, Cyst                                      18 (37%)     20 (40%)     18 (36%)     16 (33%)                               
   Prostate                                           (49)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                                                       
      Infiltration Cellular, Mononuclear Cell         25 (51%)     31 (62%)     34 (68%)     32 (64%)                               
      Inflammation, Suppurative                                                  1 (2%)                                             
      Artery, Inflammation, Chronic Active                          1 (2%)                                                          
   Seminal Vesicle                                    (49)         (50)         (50)         (50)                                   
      Atrophy                                          1 (2%)                                                                       
      Dilatation                                                    1 (2%)                                                          
      Infiltration Cellular, Mononuclear Cell                       2 (4%)       2 (4%)                                             
   Testes                                             (49)         (50)         (50)         (50)                                   
      Atrophy                                                                    1 (2%)                                             
      Inflammation, Chronic Active                                  1 (2%)                                                          
      Mineralization                                   2 (4%)       2 (4%)       1 (2%)                                             
      Germinal Epithelium, Atrophy                     1 (2%)       2 (4%)       2 (4%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (49)         (50)         (50)         (50)                                   
      Hyperplasia                                                                4 (8%)                                             
   Lymph Node                                         (3)          (5)          (3)          (1)                                    
      Inguinal, Hyperplasia, Plasma Cell                            1 (20%)                                                         
      Lumbar, Hyperplasia, Plasma Cell                              1 (20%)                                                         
      Mediastinal, Hyperplasia, Plasma Cell                         1 (20%)                                                         
      Pancreatic, Hyperplasia, Lymphoid                             1 (20%)                                                         
      Renal, Hyperplasia, Plasma Cell                               1 (20%)                                                         
      Renal, Inflammation, Suppurative                              1 (20%)                                                         
   Lymph Node, Mandibular                             (46)         (48)         (50)         (47)                                   
      Hyperplasia, Lymphoid                            1 (2%)       1 (2%)                                                          
      Hyperplasia, Plasma Cell                                      1 (2%)       1 (2%)                                             
      Infiltration Cellular, Polymorphonuclear                                   1 (2%)                                             
   Lymph Node, Mesenteric                             (46)         (43)         (49)         (47)                                   
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Hemorrhage                                       1 (2%)                                                                       
      Hyperplasia, Lymphoid                            1 (2%)       1 (2%)       1 (2%)                                             
      Hyperplasia, Plasma Cell                         1 (2%)       1 (2%)                                                          
      Inflammation, Chronic Active                                               1 (2%)       1 (2%)                                
      Inflammation, Granulomatous                      1 (2%)                                                                       
      Inflammation, Suppurative                                     1 (2%)                                                          
   Spleen                                             (49)         (50)         (50)         (50)                                   

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Hematopoietic Cell Proliferation                12 (24%)     13 (26%)     14 (28%)      4 (8%)                                
      Hyperplasia, Lymphoid                            1 (2%)       4 (8%)       1 (2%)                                             
   Thymus                                             (40)         (48)         (46)         (49)                                   
      Atypia Cellular                                                            1 (2%)                                             
      Cyst                                            16 (40%)     19 (40%)     18 (39%)     17 (35%)                               
      Ectopic Parathyroid Gland                        3 (8%)       1 (2%)       3 (7%)       1 (2%)                                
      Ectopic Thyroid                                  1 (3%)                                                                       
      Mineralization                                                1 (2%)                                                          
      Thymocyte, Necrosis                                                        1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (49)         (50)         (50)         (50)                                   
      Infiltration Cellular, Mononuclear Cell                                    1 (2%)                                             
      Inflammation, Chronic Active                                  2 (4%)       3 (6%)                                             
      Epidermis, Hyperkeratosis                                                  1 (2%)                                             
      Epidermis, Hyperplasia                                        2 (4%)       2 (4%)                                             
      Epidermis, Ulcer                                              2 (4%)       2 (4%)                                             
      Epidermis, Pinna, Hyperplasia                                              1 (2%)                                             
      Epidermis, Pinna, Ulcer                                                    1 (2%)                                             
      Pinna, Inflammation, Chronic Active                                        1 (2%)                                             
      Subcutaneous Tissue, Fibrosis                                 1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Lung                                               (49)         (50)         (50)         (50)                                   
      Hemorrhage                                                    1 (2%)       1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell          1 (2%)       1 (2%)                                                          
      Inflammation, Chronic                                         1 (2%)                                                          
      Inflammation, Chronic Active                     2 (4%)       2 (4%)                    4 (8%)                                
      Mineralization                                   3 (6%)       1 (2%)                    2 (4%)                                
      Thrombosis                                       3 (6%)       2 (4%)       1 (2%)       1 (2%)                                
      Alveolar Epithelium, Hyperplasia                 3 (6%)       6 (12%)      5 (10%)      4 (8%)                                
      Alveolus, Infiltration Cellular, Histiocyte      4 (8%)       8 (16%)      3 (6%)       3 (6%)                                
      Bronchiole, Foreign Body                         1 (2%)                                                                       

a  Number of animals examined microscopically at site and number of animals with lesion                                             
NTP Experiment-Test: 88050-06         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                         METHACRYLONITRILE                                     Date: 10/25/99  
Route: GAVAGE                                                                                                     Time: 08:32:57  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          0 MG/KG      1.5          3 MG/KG      6 MG/KG                                   
                                                                MG/KG                                                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
RESPIRATORY SYSTEM - CONT                                                                                                           
      Mediastinum, Inflammation, Chronic Active                                               1 (2%)                                
      Mediastinum, Inflammation, Suppurative                        1 (2%)                                                          
      Pleura, Inflammation, Chronic Active                                                    1 (2%)                                
   Nose                                               (49)         (50)         (50)         (50)                                   
      Foreign Body                                     3 (6%)       3 (6%)       4 (8%)       1 (2%)                                
      Inflammation, Chronic Active                     2 (4%)                    3 (6%)                                             
      Nasolacrimal Duct, Inflammation, Suppurative     4 (8%)                    1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                (1)          (1)                       (1)                                    
      Cornea, Inflammation, Chronic Active                          1 (100%)                                                        
      Cornea, Inflammation, Suppurative                1 (100%)                                                                     
      Cornea, Metaplasia, Squamous                                  1 (100%)                                                        
   Harderian Gland                                    (3)          (2)          (7)          (1)                                    
      Infiltration Cellular, Mononuclear Cell          1 (33%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (49)         (50)         (50)         (50)                                   
      Infarct                                          2 (4%)       2 (4%)       1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell         27 (55%)     37 (74%)     39 (78%)     22 (44%)                               
      Inflammation, Chronic Active                     1 (2%)                    1 (2%)                                             
      Inflammation, Suppurative                                                  1 (2%)                                             
      Metaplasia, Osseous                              2 (4%)       1 (2%)                                                          
      Mineralization                                  43 (88%)     49 (98%)     47 (94%)     36 (72%)                               
      Nephropathy                                     43 (88%)     48 (96%)     47 (94%)     39 (78%)                               
      Artery, Inflammation, Chronic Active                          1 (2%)                                                          
      Cortex, Cyst                                    11 (22%)     12 (24%)      8 (16%)      9 (18%)                               
      Renal Tubule, Hyperplasia                        9 (18%)      8 (16%)      9 (18%)      2 (4%)                                
      Renal Tubule, Necrosis                           1 (2%)                                                                       
   Urinary Bladder                                    (49)         (50)         (50)         (50)                                   
      Hemorrhage                                                                 1 (2%)                                             
      Infiltration Cellular, Mononuclear Cell         12 (24%)     17 (34%)      9 (18%)     10 (20%)                               
      Inflammation, Suppurative                                                  1 (2%)                                             
                                                                                                                                    

a  Number of animals examined microscopically at site and number of animals with lesion                                             
                             ------------------------------------------------------------                                           
                             ----------              END OF REPORT             ----------                                           
                             ------------------------------------------------------------