Light and electron microscope studies of grass carp (Ctenopharyngodon idella) organs following exposure to various sublethal concentrations of diazinon

Histopathological effects of different sublethal concentrations (1, 2 and 4mg/l) of diazinon, an organophosphorus pesticide, on gill, liver, spleen and kidney ofgrass carp (ctenopharyngodon idella) were studied after i, 7, 15,30 and 45 dayspost-exposing fishes weighting 850 ± 155 g to the toxicant for 12 hours at 18-22°c.in addition, tissues of nostril were examined for transmission electron microscopyand scanning electron microscopy. results of light microscopic examinations oftissues showed that toxicant was causing severe histopathological effects such ascongestion of blood vessels, haemorrhage, cellular infiltration, pyknosis of cellsnuclei, vacuolar degeneration and general necrosis in the kidney, spleen and liver.there were also degenerative changes of interstitial tissue and detachment of tubularbasement membrane in kidney observed. hyperplasia and fusion of secondary lamel1ae, separation and sloughing of epithelium from the underlying basementmembrane were also observed in gill sections. transmission electron microscopy(tem) examination of nostril revealed, damages of epithelial cel1s (vacuolated clubcel1s and abnormality in cel1s' nuclei). scanning electron microscopy (sem)examination of nostril showed a reduction in excretion of amorphous proteinousmaterials, reduction in vesicle numbers on the cel1 surface and also closing of cellsurface canals.