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TDMS Study 05158-04 Pathology Tables

NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23




       Facility:  Battelle Northwest

       Chemical CAS #:  1313-27-5

       Lock Date:  07/13/93

       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: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Moribund Sacrifice                                17           12           14           10                                     
    Natural Death                                      8            6            2            5                                     
    Accidently Killed                                               1            1                                                  
  Survivors                                                                                                                         
    Terminal Sacrifice                                24           31           31           35                                     
    Moribund Sacrifice                                 1                         2                                                  

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Esophagus                                          (50)         (50)         (49)         (50)                                   
      Inflammation                                                  2 (4%)       1 (2%)                                             
      Epithelium, Hyperplasia                                                    1 (2%)                                             
   Gallbladder                                        (40)         (44)         (46)         (41)                                   
      Cyst                                                                                    1 (2%)                                
      Inflammation, Suppurative                        1 (3%)                                 1 (2%)                                
   Intestine Small, Duodenum                          (43)         (46)         (47)         (46)                                   
      Epithelium, Hyperplasia                                                                 1 (2%)                                
      Peyer's Patch, Hyperplasia                                                 1 (2%)                                             
   Intestine Small, Jejunum                           (44)         (45)         (47)         (46)                                   
      Epithelium, Hyperplasia                                                                 1 (2%)                                
      Peyer's Patch, Hyperplasia                                                              2 (4%)                                
   Intestine Small, Ileum                             (45)         (45)         (47)         (46)                                   
      Peyer's Patch, Hyperplasia                       1 (2%)                                                                       
   Liver                                              (50)         (50)         (50)         (49)                                   
      Angiectasis                                      1 (2%)                                 1 (2%)                                
      Basophilic Focus                                              1 (2%)                    1 (2%)                                
      Degeneration, Fatty                                           1 (2%)                    1 (2%)                                
      Eosinophilic Focus                               5 (10%)     15 (30%)     12 (24%)      4 (8%)                                
      Hematopoietic Cell Proliferation                 2 (4%)                    3 (6%)       2 (4%)                                
      Hepatodiaphragmatic Nodule                       1 (2%)                                                                       
      Inflammation, Chronic                                         1 (2%)       1 (2%)       1 (2%)                                
      Mixed Cell Focus                                              1 (2%)                                                          
      Necrosis                                         5 (10%)      3 (6%)       2 (4%)       3 (6%)                                
      Vacuolization Cytoplasmic                        1 (2%)                    1 (2%)                                             
      Bile Duct, Cyst                                  2 (4%)                    1 (2%)       1 (2%)                                
      Centrilobular, Degeneration                                   1 (2%)       2 (4%)       1 (2%)                                
      Centrilobular, Hypertrophy                                                 2 (4%)                                             
   Mesentery                                          (4)          (9)          (9)          (7)                                    
      Artery, Inflammation, Chronic                                              1 (11%)                                            
      Fat, Necrosis                                    3 (75%)      8 (89%)      5 (56%)      7 (100%)                              
   Pancreas                                           (50)         (49)         (48)         (46)                                   

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

                                                             Page    2                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Atrophy                                          3 (6%)       2 (4%)       4 (8%)       6 (13%)                               
      Basophilic Focus                                              1 (2%)                    1 (2%)                                
      Hyperplasia                                      1 (2%)       2 (4%)                                                          
      Hypertrophy                                                   1 (2%)       1 (2%)       1 (2%)                                
      Inflammation, Chronic                            1 (2%)                                                                       
      Duct, Cyst                                                    1 (2%)                    2 (4%)                                
   Stomach, Forestomach                               (50)         (50)         (49)         (47)                                   
      Diverticulum                                                                            1 (2%)                                
      Inflammation                                                  1 (2%)       1 (2%)       1 (2%)                                
      Inflammation, Suppurative                                                               1 (2%)                                
      Ulcer                                            2 (4%)                                                                       
      Epithelium, Hyperplasia                          1 (2%)       3 (6%)       1 (2%)       3 (6%)                                
   Stomach, Glandular                                 (49)         (49)         (47)         (46)                                   
      Inflammation, Chronic                                         1 (2%)                                                          
      Necrosis                                         1 (2%)                                                                       
      Epithelium, Hyperplasia                          1 (2%)       1 (2%)                                                          
   Tooth                                              (2)                                                                           
      Developmental Malformation                       1 (50%)                                                                      
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Blood Vessel                                       (2)                                                                           
      Inflammation, Chronic                            1 (50%)                                                                      
      Mineralization                                   1 (50%)                                                                      
   Heart                                              (50)         (50)         (49)         (49)                                   
      Cardiomyopathy                                  39 (78%)     42 (84%)     43 (88%)     43 (88%)                               
      Mineralization                                   2 (4%)                    1 (2%)                                             
      Artery, Inflammation                                                                    1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (50)         (49)         (49)                                   
      Hematopoietic Cell Proliferation                                           2 (4%)                                             
      Hyperplasia                                      1 (2%)       3 (6%)       1 (2%)       2 (4%)                                
      Hypertrophy                                      5 (10%)      3 (6%)       4 (8%)       6 (12%)                               
   Adrenal Medulla                                    (50)         (49)         (49)         (49)                                   
      Hyperplasia                                      4 (8%)       5 (10%)      6 (12%)      3 (6%)                                
   Islets, Pancreatic                                 (50)         (49)         (48)         (46)                                   
      Hyperplasia                                      4 (8%)       2 (4%)       1 (2%)                                             
   Parathyroid Gland                                  (31)         (39)         (37)         (33)                                   
      Hyperplasia                                                   1 (3%)                                                          
   Pituitary Gland                                    (49)         (48)         (48)         (49)                                   
      Pars Distalis, Hyperplasia                      13 (27%)     23 (48%)     15 (31%)     17 (35%)                               
      Pars Intermedia, Hyperplasia                     1 (2%)       3 (6%)       1 (2%)                                             
   Thyroid Gland                                      (50)         (50)         (49)         (49)                                   

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

                                                             Page    3                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ENDOCRINE SYSTEM - CONT                                                                                                             
      Inflammation, Chronic                                                                   1 (2%)                                
      Follicular Cell, Hyperplasia                    15 (30%)     16 (32%)     14 (29%)     18 (37%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Ovary                                              (50)         (49)         (48)         (46)                                   
      Angiectasis                                      1 (2%)       3 (6%)       2 (4%)       1 (2%)                                
      Atrophy                                          5 (10%)      5 (10%)      6 (13%)      4 (9%)                                
      Cyst                                            22 (44%)     15 (31%)     16 (33%)     11 (24%)                               
      Degeneration, Fatty                                                        1 (2%)                                             
      Hemorrhage                                       1 (2%)                                                                       
      Hyperplasia                                      1 (2%)       1 (2%)       1 (2%)                                             
      Inflammation, Chronic                                         1 (2%)                                                          
      Metaplasia, Osseous                                           1 (2%)                                                          
      Thrombosis                                       1 (2%)                                                                       
      Corpus Luteum, Hyperplasia                                    2 (4%)       1 (2%)                                             
      Interstitial Cell, Hyperplasia                                2 (4%)                                                          
   Uterus                                             (50)         (50)         (49)         (49)                                   
      Angiectasis                                      2 (4%)       2 (4%)       1 (2%)       3 (6%)                                
      Hydrometra                                                    1 (2%)       3 (6%)       4 (8%)                                
      Hyperplasia, Cystic                              2 (4%)       2 (4%)       3 (6%)       1 (2%)                                
      Inflammation, Suppurative                        1 (2%)                    3 (6%)       3 (6%)                                
      Thrombosis                                       1 (2%)                                                                       
      Endometrium, Hemorrhage                                                    1 (2%)                                             
      Endometrium, Hyperplasia                         1 (2%)       1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (49)         (49)                                   
      Angiectasis                                      1 (2%)                                                                       
      Hyperplasia                                      1 (2%)                    4 (8%)                                             
      Infiltration Cellular, Mast Cell                                                        1 (2%)                                
      Necrosis                                                                   1 (2%)                                             
   Lymph Node                                         (4)          (6)          (7)          (4)                                    
      Angiectasis                                                   1 (17%)                   2 (50%)                               
      Iliac, Congestion                                1 (25%)                                                                      
      Iliac, Hyperplasia                               2 (50%)      2 (33%)      1 (14%)      1 (25%)                               
      Lumbar, Hyperplasia                                                        1 (14%)                                            
      Renal, Congestion                                1 (25%)                                                                      
      Renal, Hyperplasia                               1 (25%)      1 (17%)                   1 (25%)                               

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

                                                             Page    4                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
   Lymph Node, Bronchial                              (41)         (32)         (36)         (31)                                   
      Hyperplasia                                      2 (5%)       3 (9%)       1 (3%)       4 (13%)                               
   Lymph Node, Mandibular                             (39)         (40)         (43)         (40)                                   
      Angiectasis                                      1 (3%)                                                                       
      Hyperplasia                                      2 (5%)       7 (18%)      6 (14%)      5 (13%)                               
   Lymph Node, Mesenteric                             (49)         (49)         (46)         (44)                                   
      Angiectasis                                                   1 (2%)                                                          
      Congestion                                       1 (2%)                    1 (2%)                                             
      Hyperplasia                                      4 (8%)       8 (16%)      5 (11%)      5 (11%)                               
   Lymph Node, Mediastinal                            (41)         (41)         (40)         (41)                                   
      Hyperplasia                                      3 (7%)       5 (12%)      2 (5%)       4 (10%)                               
   Spleen                                             (50)         (50)         (49)         (47)                                   
      Hematopoietic Cell Proliferation                16 (32%)      9 (18%)     18 (37%)     10 (21%)                               
      Hyperplasia, Lymphoid                            5 (10%)     11 (22%)      9 (18%)      9 (19%)                               
      Infiltration Cellular, Mononuclear Cell                                                 1 (2%)                                
   Thymus                                             (40)         (35)         (40)         (37)                                   
      Atrophy                                          1 (3%)                    1 (3%)                                             
      Hyperplasia, Lymphoid                                         2 (6%)       1 (3%)       1 (3%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Mammary Gland                                      (49)         (49)         (49)         (50)                                   
      Hyperplasia                                                   2 (4%)       1 (2%)                                             
   Skin                                               (50)         (50)         (49)         (50)                                   
      Inflammation, Chronic Active                                                            1 (2%)                                
      Inflammation, Focal, Granulomatous                                                      1 (2%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Fibrous Osteodystrophy                          25 (50%)     17 (34%)     19 (38%)     26 (52%)                               
      Fracture                                         1 (2%)                    1 (2%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (49)         (49)                                   
      Gliosis                                          1 (2%)                                                                       
      Necrosis                                         1 (2%)                                 1 (2%)                                
      Meninges, Inflammation, Chronic                  3 (6%)       3 (6%)       2 (4%)       3 (6%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    

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

                                                             Page    5                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (49)         (50)         (49)         (50)                                   
      Hyperplasia                                      1 (2%)       1 (2%)       7 (14%)     35 (70%)                               
      Necrosis                                                                   1 (2%)       1 (2%)                                
      Epiglottis, Hyperplasia                                       6 (12%)      1 (2%)                                             
      Epiglottis, Metaplasia                           1 (2%)                                                                       
      Epiglottis, Metaplasia, Squamous                 1 (2%)      36 (72%)     43 (88%)     49 (98%)                               
      Epiglottis, Necrosis                                                       2 (4%)       1 (2%)                                
   Lung                                               (50)         (50)         (49)         (49)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Infiltration Cellular, Histiocyte                5 (10%)      3 (6%)       2 (4%)       6 (12%)                               
      Alveolar Epithelium, Hyperplasia                 1 (2%)       3 (6%)       3 (6%)       6 (12%)                               
      Alveolar Epithelium, Metaplasia                  2 (4%)      26 (52%)     39 (80%)     46 (94%)                               
      Perivascular, Infiltration Cellular                                                     2 (4%)                                
   Nose                                               (49)         (50)         (49)         (49)                                   
      Hemorrhage                                                    1 (2%)       1 (2%)                                             
      Inflammation, Suppurative                        8 (16%)      6 (12%)      6 (12%)     16 (33%)                               
      Metaplasia, Squamous                                                       1 (2%)       2 (4%)                                
      Nasolacrimal Duct, Inflammation, Suppurative                                            1 (2%)                                
      Olfactory Epithelium, Atrophy                    5 (10%)      1 (2%)       4 (8%)       4 (8%)                                
      Olfactory Epithelium, Degeneration, Hyaline     22 (45%)     14 (28%)     14 (29%)     36 (73%)                               
      Respiratory Epithelium, Degeneration, Hyaline   26 (53%)     23 (46%)     28 (57%)     48 (98%)                               
      Respiratory Epithelium, Necrosis                 1 (2%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   Eye                                                                          (1)                                                 
      Retrobulbar, Inflammation, Suppurative                                     1 (100%)                                           
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (50)         (50)         (49)         (47)                                   
      Atrophy                                                       1 (2%)                                                          
      Hydronephrosis                                                1 (2%)       1 (2%)                                             
      Metaplasia, Osseous                              1 (2%)       2 (4%)       2 (4%)       2 (4%)                                
      Nephropathy                                     31 (62%)     30 (60%)     32 (65%)     29 (62%)                               
      Renal Tubule, Degeneration                                                 2 (4%)                                             
      Renal Tubule, Hyperplasia                                                  1 (2%)                                             
      Renal Tubule, Necrosis                           1 (2%)                                 1 (2%)                                
      Transitional Epithelium, Hyperplasia             1 (2%)                                                                       
   Urinary Bladder                                    (48)         (50)         (49)         (46)                                   

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

                                                             Page    6                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE FEMALE                        CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Inflammation, Chronic                                                      1 (2%)                                             
                                                                                                                                    

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

                                                             Page    7                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________

DISPOSITION SUMMARY                                                                                                                 

  Animals Initially In Study                          50           50           50           50                                     
  Early Deaths                                                                                                                      
    Natural Death                                      6            4           11            4                                     
    Moribund Sacrifice                                 8           13           14            9                                     
  Survivors                                                                                                                         
    Terminal Sacrifice                                36           33           25           37                                     

  Animals Examined Microscopically                    50           50           50           50                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ALIMENTARY SYSTEM                                                                                                                  
                                                                                                                                    
   Gallbladder                                        (43)         (40)         (38)         (43)                                   
      Degeneration, Hyaline                                                      1 (3%)                                             
      Inflammation, Suppurative                        1 (2%)       2 (5%)                                                          
      Epithelium, Hyperplasia                                                    1 (3%)                                             
   Intestine Large, Cecum                             (45)         (47)         (44)         (47)                                   
      Inflammation, Chronic                                         1 (2%)                                                          
   Intestine Small, Duodenum                          (44)         (47)         (41)         (48)                                   
      Epithelium, Hyperplasia                                                    1 (2%)                                             
   Intestine Small, Ileum                             (44)         (46)         (41)         (48)                                   
      Peyer's Patch, Hyperplasia                                                 1 (2%)                                             
   Liver                                              (50)         (50)         (50)         (50)                                   
      Amyloid Deposition                                                         1 (2%)                                             
      Angiectasis                                      1 (2%)                                 1 (2%)                                
      Basophilic Focus                                 3 (6%)       4 (8%)       1 (2%)       1 (2%)                                
      Congestion, Focal                                                          1 (2%)                                             
      Degeneration, Fatty                                           1 (2%)       2 (4%)       1 (2%)                                
      Eosinophilic Focus                              11 (22%)     10 (20%)      7 (14%)      6 (12%)                               
      Hematopoietic Cell Proliferation                 1 (2%)                    3 (6%)       2 (4%)                                
      Hepatodiaphragmatic Nodule                                                 1 (2%)                                             
      Infiltration Cellular, Mast Cell                                                        1 (2%)                                
      Inflammation, Chronic                            1 (2%)       1 (2%)       3 (6%)                                             
      Necrosis                                         5 (10%)      5 (10%)      5 (10%)      5 (10%)                               
      Vacuolization Cytoplasmic                        1 (2%)       1 (2%)                    1 (2%)                                
      Bile Duct, Cyst                                  1 (2%)                    1 (2%)       1 (2%)                                
      Centrilobular, Degeneration                                   1 (2%)                                                          
      Centrilobular, Necrosis                          1 (2%)                                                                       
      Serosa, Fibrosis                                              1 (2%)                    1 (2%)                                
   Mesentery                                          (3)          (4)          (2)          (2)                                    
      Congestion                                                    1 (25%)                                                         
      Hemorrhage                                                    1 (25%)                                                         
      Fat, Necrosis                                    3 (100%)     3 (75%)      2 (100%)     1 (50%)                               
   Pancreas                                           (50)         (48)         (48)         (50)                                   
      Atrophy                                          8 (16%)      3 (6%)       4 (8%)       8 (16%)                               
      Basophilic Focus                                              1 (2%)       1 (2%)                                             

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

                                                             Page    8                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
ALIMENTARY SYSTEM - CONT                                                                                                            
      Hyperplasia                                                                             1 (2%)                                
      Hypertrophy                                                                2 (4%)                                             
   Salivary Glands                                    (50)         (50)         (49)         (50)                                   
      Inflammation, Suppurative                                     2 (4%)                                                          
   Stomach, Forestomach                               (50)         (49)         (48)         (50)                                   
      Inflammation                                                  1 (2%)                                                          
      Ulcer                                            1 (2%)                                                                       
      Epithelium, Hyperplasia                          2 (4%)       2 (4%)       1 (2%)       1 (2%)                                
   Stomach, Glandular                                 (50)         (48)         (46)         (49)                                   
      Inflammation, Suppurative                                                  2 (4%)                                             
      Necrosis                                                      1 (2%)       1 (2%)                                             
      Epithelium, Hyperplasia                                                                 1 (2%)                                
   Tooth                                                           (1)          (1)          (1)                                    
      Developmental Malformation                                                              1 (100%)                              
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 CARDIOVASCULAR SYSTEM                                                                                                              
                                                                                                                                    
   Heart                                              (50)         (50)         (49)         (50)                                   
      Cardiomyopathy                                  44 (88%)     48 (96%)     46 (94%)     47 (94%)                               
      Mineralization                                                                          1 (2%)                                
      Atrium, Thrombosis                                            1 (2%)                                                          
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 ENDOCRINE SYSTEM                                                                                                                   
                                                                                                                                    
   Adrenal Cortex                                     (50)         (49)         (48)         (50)                                   
      Hemorrhage                                                    1 (2%)                                                          
      Hyperplasia                                      8 (16%)     11 (22%)     10 (21%)      5 (10%)                               
      Hypertrophy                                     24 (48%)     29 (59%)     27 (56%)     30 (60%)                               
      Capsule, Hyperplasia                             1 (2%)                                 1 (2%)                                
   Adrenal Medulla                                    (50)         (49)         (48)         (50)                                   
      Hyperplasia                                      1 (2%)       2 (4%)       2 (4%)                                             
   Islets, Pancreatic                                 (50)         (48)         (48)         (50)                                   
      Hyperplasia                                      1 (2%)       6 (13%)      3 (6%)       4 (8%)                                
   Parathyroid Gland                                  (36)         (39)         (31)         (35)                                   
      Hyperplasia                                                                1 (3%)                                             
   Pituitary Gland                                    (47)         (47)         (46)         (47)                                   
      Pars Distalis, Cyst                                           1 (2%)                                                          
      Pars Distalis, Hyperplasia                                    3 (6%)       2 (4%)                                             
   Thyroid Gland                                      (50)         (50)         (49)         (50)                                   
      Follicular Cell, Hyperplasia                    20 (40%)     19 (38%)     12 (24%)     15 (30%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    

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

                                                             Page    9                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENERAL BODY SYSTEM                                                                                                                
                                                                                                                                    
   Peritoneum                                         (1)                                                                           
      Inflammation                                     1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 GENITAL SYSTEM                                                                                                                     
                                                                                                                                    
   Epididymis                                         (50)         (50)         (49)         (50)                                   
      Angiectasis                                                                1 (2%)                                             
      Granuloma Sperm                                  2 (4%)                    2 (4%)                                             
      Hyperplasia, Atypical                                         1 (2%)                                                          
      Inflammation, Chronic                            3 (6%)       2 (4%)       1 (2%)       2 (4%)                                
   Penis                                                           (1)          (1)                                                 
      Capillary, Inflammation, Suppurative                          1 (100%)                                                        
   Preputial Gland                                    (49)         (50)         (48)         (50)                                   
      Cyst                                             6 (12%)      7 (14%)      8 (17%)      6 (12%)                               
      Hyperplasia                                                                1 (2%)                                             
      Inflammation                                     6 (12%)      6 (12%)      7 (15%)     11 (22%)                               
   Prostate                                           (48)         (47)         (47)         (47)                                   
      Hyperplasia                                      2 (4%)       1 (2%)                    1 (2%)                                
      Inflammation, Chronic                                                                   1 (2%)                                
      Inflammation, Suppurative                        2 (4%)       1 (2%)       1 (2%)       3 (6%)                                
   Seminal Vesicle                                    (50)         (48)         (47)         (49)                                   
      Congestion                                                    1 (2%)                                                          
      Inflammation, Chronic                                         1 (2%)                    2 (4%)                                
      Inflammation, Suppurative                        1 (2%)                                                                       
   Testes                                             (50)         (50)         (49)         (50)                                   
      Atrophy                                          2 (4%)       4 (8%)       9 (18%)      4 (8%)                                
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 HEMATOPOIETIC SYSTEM                                                                                                               
                                                                                                                                    
   Bone Marrow                                        (50)         (50)         (49)         (50)                                   
      Angiectasis                                      1 (2%)                                                                       
      Hyperplasia                                      2 (4%)       2 (4%)       2 (4%)       2 (4%)                                
      Hyperplasia, Histiocytic                         1 (2%)                                                                       
      Infiltration Cellular, Mast Cell                                                        1 (2%)                                
      Infiltration Cellular, Megakaryocyte                                                    2 (4%)                                
   Lymph Node                                         (2)          (3)          (2)          (2)                                    
      Iliac, Hyperplasia                               1 (50%)                   1 (50%)                                            
      Iliac, Pigmentation                                                        1 (50%)                                            
   Lymph Node, Bronchial                              (31)         (37)         (32)         (36)                                   
      Hyperplasia                                      1 (3%)       5 (14%)      3 (9%)       2 (6%)                                
   Lymph Node, Mandibular                             (32)         (33)         (32)         (34)                                   
      Hyperplasia                                                   1 (3%)                                                          
      Infiltration Cellular, Mast Cell                                                        1 (3%)                                
   Lymph Node, Mesenteric                             (46)         (47)         (45)         (48)                                   

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

                                                             Page   10                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
HEMATOPOIETIC SYSTEM - CONT                                                                                                         
      Angiectasis                                                   2 (4%)       1 (2%)       1 (2%)                                
      Congestion                                       1 (2%)                    1 (2%)                                             
      Hematopoietic Cell Proliferation                 1 (2%)       1 (2%)                                                          
      Hyperplasia                                      4 (9%)       4 (9%)       3 (7%)       2 (4%)                                
      Inflammation, Chronic                                                      1 (2%)                                             
   Lymph Node, Mediastinal                            (34)         (37)         (39)         (34)                                   
      Hyperplasia                                      3 (9%)       2 (5%)       1 (3%)       2 (6%)                                
   Spleen                                             (50)         (48)         (49)         (50)                                   
      Amyloid Deposition                                                         1 (2%)                                             
      Hematopoietic Cell Proliferation                11 (22%)     13 (27%)     11 (22%)      8 (16%)                               
      Hyperplasia, Lymphoid                            3 (6%)       3 (6%)       1 (2%)       1 (2%)                                
      Infiltration Cellular, Mast Cell                                                        1 (2%)                                
      Infiltration Cellular, Mononuclear Cell          1 (2%)                                                                       
      Infiltration Cellular, Histiocyte                1 (2%)                                                                       
      Pigmentation, Melanin                                         1 (2%)                                                          
   Thymus                                             (30)         (35)         (32)         (36)                                   
      Atrophy                                          1 (3%)       1 (3%)                    2 (6%)                                
      Epithelial Cell, Hyperplasia                                               1 (3%)                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 INTEGUMENTARY SYSTEM                                                                                                               
                                                                                                                                    
   Skin                                               (50)         (50)         (49)         (50)                                   
      Inflammation, Chronic Active                     1 (2%)                                 1 (2%)                                
      Prepuce, Inflammation, Chronic Active            4 (8%)       3 (6%)       4 (8%)       6 (12%)                               
      Prepuce, Inflammation, Suppurative               1 (2%)                                                                       
      Subcutaneous Tissue, Inflammation, Focal,                                                                                     
           Granulomatous                               2 (4%)                                                                       
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 MUSCULOSKELETAL SYSTEM                                                                                                             
                                                                                                                                    
   Bone                                               (50)         (50)         (50)         (50)                                   
      Degeneration                                                               1 (2%)                                             
      Fibrous Osteodystrophy                                        2 (4%)       1 (2%)                                             
      Inflammation, Chronic                                                      1 (2%)                                             
   Skeletal Muscle                                    (1)                                    (1)                                    
      Hemorrhage                                       1 (100%)                                                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 NERVOUS SYSTEM                                                                                                                     
                                                                                                                                    
   Brain                                              (50)         (50)         (49)         (50)                                   
      Gliosis                                                                                 1 (2%)                                
      Meninges, Infiltration Cellular, Mast Cell                                              1 (2%)                                
      Meninges, Inflammation, Chronic                               1 (2%)                                                          
____________________________________________________________________________________________________________________________________

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

                                                             Page   11                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
                                                                                                                                    
 RESPIRATORY SYSTEM                                                                                                                 
                                                                                                                                    
   Larynx                                             (50)         (49)         (48)         (50)                                   
      Hyperplasia                                      1 (2%)       3 (6%)       6 (13%)     41 (82%)                               
      Inflammation, Suppurative                                                  1 (2%)       1 (2%)                                
      Epiglottis, Hyperplasia                                       8 (16%)      2 (4%)                                             
      Epiglottis, Metaplasia, Squamous                             26 (53%)     37 (77%)     49 (98%)                               
   Lung                                               (50)         (50)         (49)         (50)                                   
      Hematopoietic Cell Proliferation                 1 (2%)                                                                       
      Hemorrhage                                                                 4 (8%)                                             
      Infiltration Cellular, Histiocyte                2 (4%)      16 (32%)      9 (18%)      9 (18%)                               
      Inflammation, Chronic                            1 (2%)                                                                       
      Alveolar Epithelium, Hyperplasia                 2 (4%)       1 (2%)       6 (12%)      2 (4%)                                
      Alveolar Epithelium, Metaplasia                              32 (64%)     36 (73%)     49 (98%)                               
      Artery, Inflammation                                          2 (4%)                                                          
      Perivascular, Infiltration Cellular                                                     1 (2%)                                
   Nose                                               (50)         (50)         (49)         (50)                                   
      Atrophy                                                                    1 (2%)                                             
      Infiltration Cellular, Mast Cell                                                        1 (2%)                                
      Inflammation, Suppurative                        2 (4%)       6 (12%)     10 (20%)      8 (16%)                               
      Metaplasia, Squamous                             1 (2%)       2 (4%)       3 (6%)       1 (2%)                                
      Nasolacrimal Duct, Inflammation, Suppurative     1 (2%)       2 (4%)       1 (2%)                                             
      Olfactory Epithelium, Atrophy                    3 (6%)       5 (10%)      3 (6%)      10 (20%)                               
      Olfactory Epithelium, Degeneration, Hyaline      1 (2%)       1 (2%)       1 (2%)       2 (4%)                                
      Olfactory Epithelium, Metaplasia                 1 (2%)                                 2 (4%)                                
      Respiratory Epithelium, Degeneration, Hyaline   11 (22%)     13 (26%)     11 (22%)     41 (82%)                               
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 SPECIAL SENSES SYSTEM                                                                                                              
                                                                                                                                    
   None                                                                                                                             
____________________________________________________________________________________________________________________________________
                                                                                                                                    
 URINARY SYSTEM                                                                                                                     
                                                                                                                                    
   Kidney                                             (49)         (50)         (49)         (50)                                   
      Hydronephrosis                                   1 (2%)       1 (2%)       2 (4%)       3 (6%)                                
      Inflammation, Chronic                                                                   1 (2%)                                
      Inflammation, Suppurative                        1 (2%)                    2 (4%)       2 (4%)                                
      Metaplasia, Osseous                                           2 (4%)       1 (2%)                                             
      Nephropathy                                     44 (90%)     48 (96%)     44 (90%)     46 (92%)                               
      Cortex, Cyst                                                                            1 (2%)                                
      Papilla, Necrosis                                1 (2%)                                 1 (2%)                                
      Renal Tubule, Hyperplasia                        1 (2%)       3 (6%)       3 (6%)       3 (6%)                                
      Renal Tubule, Necrosis                                                     1 (2%)                                             
   Urinary Bladder                                    (50)         (49)         (46)         (49)                                   
      Calculus Gross Observation                                                              1 (2%)                                

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

                                                             Page   12                                                              
NTP Experiment-Test: 05158-04         INCIDENCE RATES OF NONNEOPLASTIC LESIONS BY ANATOMIC SITE (a)               Report: PEIRPT03
Study Type: CHRONIC                                        MOLYBDENUM TRIOXIDE                                    Date: 04/04/96  
Route: RESPIRATORY EXPOSURE WHOLE BODY                                                                            Time: 02:35:23  
____________________________________________________________________________________________________________________________________

         B6C3F1 MICE MALE                          CONTROL      10 MG/M3     30 MG/M3     100                                       
                                                                                          MG/M3                                     
____________________________________________________________________________________________________________________________________
                                                                                                                                    
URINARY SYSTEM - CONT                                                                                                               
      Inflammation, Chronic Active                     2 (4%)                                 2 (4%)                                
      Inflammation, Suppurative                                                  2 (4%)       1 (2%)                                
      Transitional Epithelium, Hyperplasia             1 (2%)                                 2 (4%)                                
                                                                                                                                    

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

                                                             Page   13                                                              
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