Histological observations on the liver of Tilapia mossambica after exposure to monocrotophos, an organophosphorus insecticide.

The histological changes in the liver of Tilapia mossambica were observed after exposure to a sublethal level (2.5 ppm) of monocrotophos. The changes observed after 2 days of exposure were characterized by necrosis and vacuolation of hepatocytes. Fatty degeneration was observed after 10 days of exposure. However, normalization of histological picture was evident after 15 days of treatment, though some patches of degenerating zones were also found to exist concomitantly. A wave of secondary intensively degenerative changes was observed from 30 days up to 45 days of experimentation. The possible significance of histological lesions and adaptation to exposure after sublethal doses as well as continuous exposure are discussed.