Histopathological examination

Histopathological examination (up to 40 different tissues were post-mortem and examined for abnormality). 

Histopathological examination shows the typical corelike lesions in a high proportion of muscle fibers in older patients this may amount to 100%. Most typically the cores are large and centrally-placed, but multiple cores may occur in the same fiber cross section. Most older patients show a striking predominance of type 1 (slow twitch oxidative) fibers and virtually all fibers with cores are type 1. Sometimes younger family members have more normal proportions of type 1 and type 2 fibers but, again, the cores are confined to the type 1 fibers. It is well established that muscle fiber types can interconvert due to altered physiological demands, and it is likely that fibers with cores convert to a basically slow twitch-oxidative metabolism to compensate for the fact that up to 50% of their cross sectional area may be devoid of mitochondria. 

The histopathological examination of mice liver performed after a single dose of dibromobenzenes shows that 2 and 2 isomers resulted in zonal coagulative or haemorragic necrosis. It affected from 25-50 % to over 50 % of the liver parenchyma (i.e. 4-5 arbitrary units). 4 caused necrosis of only individual hepatocytes. 

Histopathological examination of rats liver carried out after 7-fold administration of the studied compounds points out that the most visible pathological lesion is steatosis of all zones. 

No changes in GTP and y-GT activity were recorded after repeated administration of the above compounds. Also, histopathological examination did not point to liver necrosis. Similar phenomenon detected earlier after repeated administration of monobromobenzene, was interpreted as a result of damage of the microsomal enzymatic system responsible for the appearance of active metabolites (ref. 22). 

Routine gross and histopathological examinations revealed no treatment-related effects on the respiratory system of dogs exposed to 0.03, 0.1, or 0.3 mg/kg/day methyl parathion in the diet for 1 year (Suba 1981). Chronic dietary exposure to methyl parathion did not induce respiratory effects in mice fed 16.2 mg/kg/day or rats fed 2 mg/kg/day (NCI 1979). 

Cardiovascular Effects. No studies were located regarding cardiovascular effects in humans after inhalation exposure to endosulfan. Routine gross and histopathologic examination of the heart and aorta of rats exposed (nose-only) to concentrations of endosulfan of up to 2 mg/m for 6 hours/day,... 

Also, chronic-duration studies have not generally shown adverse effects on organs of the immune system. Routine gross and histopathologic examination of the lymph nodes and thymus of rats, mice, and dogs exposed to endosulfan for 2 years at doses of up to 2.9 mg/kg/day (Hoechst 1989a), 2.51 mg/kg/day (Hoechst 1988b), and 1 mg/kg/day (EMC 1967), respectively, revealed no adverse effects. However, these studies did not assess immune function directly. 

Diarrhea was observed in rats exposed for 5 days, 6 hours/day to both lethal and sublethal doses of P-endosulfan ( 250 mg/kg/day for males and i6 mg/kg/day for females) (Hoechst 1989b). Autopsy of animals from this study revealed that the mesenteric blood vessels of one of the surviving females exposed to 16 mg/kg/day were distended with blood, and that the small intestines of animals dying as a result of exposure were filled with a reddish fluid (500 mg/kg/day for males and 31.25 for mg/kg/day females). In contrast, no treatment-related effects were revealed by routine gross and histopathological examination of gastrointestinal tissues (stomach, small and large intestines, and pancreas) from rats exposed to doses of 27 mg/kg/day (females) and 81 mg/kg/day (males) for 30 days, 6 hours/day,... 

Histopathologic examination of tissues of selected birds from the 2,3,7,8-TCDD (1 and 10 fig) and HCDD (10 and 100 fig) groups revealed... 

Rales and dyspnea were observed in pregnant rats treated by gavage with 1,500 mg/kg/day trichloroethylene in com oil on gestation days 6-19 (Narotsky and Kavlock 1995). Respiratory effects were not observed at 1,125 mg/kg/day. Pulmonary vasculitis was observed in 6 of 10 female rats treated with 1,000 mg/kg/day (by gavage) and 6 of 10 male rats treated with 2,000 mg/kg/day (in com oil) for 13 weeks (NTP 1990). This effect was also observed in 1 of 10 male and 1 of 10 female control rats. Histopathological examinations were not completed at the other doses in this study. Therefore, it is not possible to determine if this is a dose-related effect. 

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