Pathological study of experimental cadmium toxicity in common carp (Cyprinus carpio L

Abstract

The median lethal concentration of cadmium chloride CdCl2 at 24 hour in Cyprinus carpioL was determined. The toxic effect of sublethal concentration of CdCl2 was studied for 4, 7, 15 day. There was estimated significant decrease in hemoglobin concentration, Packed cell volume (PCV) and lymphocyte counts, with significant increase (P≤0.05) in the serum alanine aminotransferase and creatine phosphokinase activity correlated with progression of exposure period. The elevation was more significant on the 15th day in all groups in comparison with non treated control group. The fish treated with sublethal concentration of CdCl2 showed behaviors of nervous signs manifested as abnormal swimming and jumping above the water surface. The gross lesions of sublethal concentration toxic effects included congestion of gills. Histopathological lesions revealed hyperplasia of epithelial cells with hyperatrophy of piler cells and inflammatory cells infiltration which lead to adhesion of the secondary lamellae of gills. The same lesions were observed on the 15th day of exposure but were more severe. In liver and kidney which appeared congested with presence of pale areas, histopathological lesions include infiltration of inflammatory cells, specially melanomacrophage and mononuclear cells in hepatic tissue with thickening of the bile duct wall, hemorrhage and necrosis in hepatic tissue. In the kidney, there was a congestion of blood vessels and deposition of hyaline casts in the renal tubules. Accumulation of cadmium in gills, kidney and liver after 4, 7 and 15th day of exposure showed an increase in level of accumulation with progression of exposure period.