No abstract

ABSTRACT

The histopathological effects of monocrotophos on the gill, kidney and intestine tissues of the Cirrhinus mrigala were determined by light microscopy. The changes in the gills were characterized by epithelial hyperplasia, aneurysm, epithelial necrosis, desquamation, epithelial lifting, oedema, lamellar fusion and curling of secondary lamellae. Pycnotic nuclei in tubular epithelium, hypertrophied epithelial cells of renal tubules, contraction of the glomerulus and expansion of space inside the Bowman's capsule were observed in the kidney tissues of fish after exposure to monocrotophos. In the intestine tissues of fish exposed to monocrotophos, oedema, necrosis and atrophy of epithelial cells were observed.

Gill, liver and kidney of Clarias gariepinus were examined histologically after exposure to sublethal concentrations (10.05, 20.10 and 30.15 microg/L) of cypermethrin for 10 days. Histological recovery was also studied by maintaining the pesticide-exposed fish in a fresh water system for an additional 10 days. Epithelial hypertrophy and hyperplasia, epithelial lifting, oedema, fusion of secondary lamellae, necrosis and desquamation were histopathological changes in the gills of fish exposed to cypermethrin. Hepatic lesions in the liver tissues of fish were characterized by cloudy swelling of hepatocytes, lipoid vacuoles, pycnotic nuclei and focal necrosis. Epithelial hypertrophy, narrowing of the tubular lumen, atrophy of the glomerulus, broader Bowman's capsule, necrosis in the epithelial cells and pycnosis in the hematopoietic tissue were observed in kidney tissues of fish. These lesions grew with increasing concentration. Although some of the changes were reversible, the rest were less pronounced after a recovery period; a period of 10 days was not long enough for complete recovery.

The histopathological changes of fenvalerate on the gill, kidney, liver and intestine tissues of the Cirrhinus mrigala were determined by light microscopy. The fish were exposed to two sub-lethal concentrations of fenvalerate (1.5-3.0 ppb). The most common gill changes at all concentrations of fenvalerate were epithelial hyperplasia, epithelial necrosis, desquamation and lamellar fusion. Besides, epithelial lifting, oedema, swelling at the tips of secondary lamellae and curling of secondary lamellae were other histopathological changes. Necrosis of tubular epithelium, pycnotic nuclei in the hematopoietic tissue, hypertrophied epithelial cells of renal tubules, narrowing of the tubular lumen, expansion of space inside the Bowman's capsule and contraction of the glomerulus were observed in kidney tissues of fish. Hepatic lesions in the liver tissues of fish exposed to fenvalerate were characterized by congestion, cloudy swelling of hepatocytes and focal necrosis. Atrophy of epithelial cells, necrosis of epithelial cells, desquamation of mucosal epithelium and infiltration of lymphocytes into the lamina propria were detected in intestine tissues of fish after exposure to fenvalerate.