Document Type : Original Article


Plant Prot. Dept., Fac. Agric., Zagazig Univ., Egypt


The present study was designed to evaluate the toxic effects induced by different time intervals of methomyl exposure on the histological changes in liver, kidneys, lungs and heart of albino rats. Three treatment groups of rats were employed. The 1st group was served as control, while the 2nd and 3rd groups were orally treated with 1/10 LD50 (3.33 mg a.i./kg b.wt.) and 1/20 LD50 (1.66 mg a.i./kg b.wt.) of methomyl, respectively, for five days. The histology of rat liver treated with methomyl 1/10 LD50 showed portal lymphohistiocytic aggregations, proliferative bile ductules, dilated portal, and central vein with widening of hepatic sinusoids, which found in common. Besides, siderocytes were seen accompanying the inflammatory infiltrates with various types of cell injury of the hepatic cells. Focal interstitial and interasinusoidal infiltrations of inflammatory cells mainly lymphohistiocytic cells and hemosiderosis were observed with 1/20 LD50 and some hepatic cells had acute cell swelling which contains hemosiderosis accompanied hypertrophy of kuffer cells. Histopathological studies showed that degeneration of tubular epithelia were common in kidneys treated with 1/10 LD50 and some tubules contain hyaline and granular casts, as well as other necrotic tubules were seen with lymphocytic infiltration in the renal cortex. Meanwhile, the results of 1/20 LD50 treatment showed small focal tubular necrosis or different forms of acute cell swelling and some tubules contain desquamated cells inside its lumen in kidneys. Lungs were thickened with irregular bronchiolar wall due to leukocytic infiltration, peribronchial lymphoid hyperplasia, and desquamated bronchiolar epithelium with 1/10 LD50 methomyl. Furthermore, focal lymphocytic aggregations replacing the pulmonary tissue with mild perivascular lymphocytic infiltration were observed at same dose. Mild hyperplasia of peribronchial lymphoid tissue including mild thickening of interalveolar septae accompanied with minute perivascular lymphocytic aggregations were the common pulmonary lesions with 1/20 LD50. The heart had severe dilatation and widening of intramuscular blood vessels with partial hyalinization of some myocardial muscle fibers beside intramuscular edema which treated with 1/10 LD50. On the other hand, it was normal cardiac muscle and intramuscular blood vessels at 1/20 LD50 treatment. It could be concluded that the 1/10 LD50 dose of methomyl had a significant histopathologicalchanges in the studied albino rat organs. The pesticide administration caused extensive destruction to the renal tissue. This damage was more pronounced in the higher dose.