Morphological and biochemical studies on liver, kidney and gill of fishes affected by pesticides.

Effect of a herbicide, paraquat (1,1'-dimethyl-4,4'-bipyridilium-dichloride), the fungicide copper sulphate, and zinc chloride was studied on the histological structure of liver, kidney and gill of three fish species with different feeding habits, viz.: a herbivorous, silver carp (Hypophthalmichthys molitrix); an omnivorous, common carp (Cyprinus carpio L.) and a carnivorous, sheatfish (Silurus glanis L.). The organs were studied electron microscopically after fixation according to Karnovsky. The toxic effect manifested itself characteristically on the respective species, regardless of the type of the chemical applied and the species specificity. Upon the effect of the treatments applied the cytoplasm of the respiratory cells of the gill became electron transparent and the cytoplasmic organelles disappeared almost totally. In the chloride cells showing focal necrosis, residuals of nuclear, mitochondrial and endoplasmic origin were seen. Pillar cells and the pericytes remained intact. In the nucleus of the liver cells, electron dense heterochromatin was not present. The degree of the damage in the liver cells was indicated by swollen mitochondria with electron transparent matrix and by dilatation and vacuolation of the endoplasmic reticulum system. Epithelial cells decreased in electron density, the endoplasmic reticulum was vesiculated, mitochondria were swollen. Leucocytes increased in number, and empty vacuoles and vacuoles filled with dense granules appeared in them during toxicosis. Copper sulphate or paraquat increased serum transaminase enzyme activities (glutamic acid-oxalacetic acid transaminase, glutamic acid-pyruvic acid transaminase) in all the three fish species. These damages can cause serious disturbances in energy uptake and secretion processes of fish.