Histopathological changes due to some chlorinated hydrocarbon pesticides in the tissues to cyprinus carpio

Abstract

––Chronic bioassay studies were carried out using the chlorinated hydrocarbon pesticides like DOT, BHC, Aldrin and Dieldrin using fresh water fish Cyprinus carpio as test organism. The aim of the studies were : i) the effect of these chlorinated hydrocarbons on fish on prolonged exposure to the sublethal concentration levels determined from acute toxicity studies; ii) their effect on vital internal organs (Histopathological studies) such as gill, kidney, liver and intestine, before and after the exposure, to ascertain internal injury, if any. The accumulation of the chlorinated hydrocarbons in different tissues clearly indicate the potential hazards of the pesticides. In small doses, these may not be detrimental from water pollution point of view, but can create great hazard by accumulating in fish tissues. Different tissues showed different accumulation of pesticides. Histopathological changes were observed in vital organs. Gills showed swelling and thickening in their filaments. In some cases, the epithelial wall of the secondary lamellae was completely destroyed and the pillar cells showed complete fusion. Mucous cells were completely destroyed. In most cases, the epithelium of the secondary lamellae was separated from the supporting pillar cells. Complete necrosis and sloughing of secondary lamellae from the supporting pillar cells was observed. Liver showed abnormal fatty degeneration. Enlargement of liver was observed in few cases. Necrosis, congestion and fatty degeneration were also observed. Kidney tissue also showed abnormalities. Large vacuolated cells were seen in the glomerulii. Acute tubular necrosis was seen. The glomerulii were shrunken with sloughed necrotic glomerulii lining cells in the lumen. Intestine showed fusion of intestinal folds and acute epithelial necrosis.