Cytological and histological effects of pesticide chlorpyriphos in the gills of Anabas testudineus.

The present study was aimed to report the toxicity of the chlorpyrifos, an organophosphorus insecticide, with regard to histological and cytological effects through light and transmission electron microscopes in the gills of freshwater fish, Anabas testudineus. The fish were exposed to 0.125 (5% of 96 h LC50), 0.250 (10% of 96 h LC50), and 0.375 mgL-1 (15% of 96 h LC50) of chlorpyrifos for 7, 14, and 21 days for light microscopy and 21 days for transmission electron microscopy. The histological effects were seen in all exposed concentrations of 0.125, 0.250, and 0.375 mgL-1. These effects increased with the increase in chlorpyrifos concentrations and duration of exposure. The main histological effects visible in the gill tissue were fusion of secondary lamellae and epithelial hyperplasia. Other effects included the epithelial hypertrophy, lifting of lamellar epithelium, aneurysm, necrosis, and desquamation of epithelial cells were also reported. Cytological effects included epithelial detachment, large subepithelial space, necrotic cells, apoptotic remnant of cells, the presence of macrophages, swelling of mitochondria in the chloride cells, distension of the tubular system, the presence of some large vacuoles, deposition of excessive mucous, and nucleus abnormalities. This study confirms that varying doses of chlorpyrifos have adverse histological and cytological effects in the gills of A. testudineus.

Histopathological changes in the gill and liver tissues of freshwater fish, Cirrhinus mrigala exposed to dichlorvos

The histopathological effects of dichlorvos, an organophosphate pesticide, on the gill and liver tissues in Cirrhinus mrigala were determined by light microscopy. The fishes were exposed to sublethal concentrations (0.91 and 1.82 ppm) of dichlorvos for 10 days with parallel untreated control. No histopathological effects were observed in control group. Hyperplasia, desquamation, and necrosis of epithelial, epithelial lifting, oedema, lamellar fusion, collapsed secondary lamellae, curling of secondary lamellae and aneurism in the secondary lamellae were observed in gill tissues exposed to dichlorvos. Hepatic lesions in the liver tissues of fishes exposed to dichlorvos were characterized by cloudy swelling of hepatocytes, congestion, vacuolar degeneration, karyolysis, karyohexis, dilation of sinusoids and nuclear hypertrophy.

Histopathological effects of cypermethrin on gill, liver and kidney of fresh water fish Clarias gariepinus (Burchell, 1822), and recovery after exposure.

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.

Levels of transaminases, alkaline phosphatase, and protein in tissues of Clarias gariepienus fingerlings exposed to sublethal concentrations of cadmium chloride.

The freshwater fish, Clarias gariepienus fingerlings, were exposed to sublethal concentrations (1.7 and 3.4 mg/L) of cadmium chloride for 12 days. Aspartate aminotransferase (AAT), alanine aminotransferase (ALT), alkaline phosphatase (ALP), and total protein levels were assayed in the gill, brain, and muscle of the fish at regular intervals of 6 and 12 days. The activities of AAT, ALT, and ALP of the treated fishes increased significantly in all the tissues compared with the control fish. Protein level in all the tissues showed a significant decrease in comparison to unexposed controls throughout the experimental periods. These results revealed that cadmium chloride effects the intermediary metabolism of C. gariepienus fingerlings and that the assayed enzymes can work as good biomarkers of contamination.

The effects of fenvalerate on different tissues of freshwater fish Cirrhinus mrigala.

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.

Histopathology of lambda-cyhalothrin on tissues (gill, kidney, liver and intestine) of Cirrhinus mrigala.

The histopathology of lambda-cyhalothrin, a synthetic pyrethroid pesticide, on the gill, liver, intestine and kidney tissues in fish, mrigal (Cirrhinus mrigala), which is one of Indian major carp species were determined by light microscopy. The fish were experimentally exposed to sub-lethal concentrations (0.3ppb and 0.6ppb) of lambda-cyhalothrin for 10 days. Tissues were normal in the control group. Epithelial hyperplasia, aneurism, epithelial necrosis, desquamation, epithelial lifting, oedema, shortening of secondary lamellae and lamellar fusion were observed in gill tissues exposed to lambda-cyhalothrin. Necrosis of tubular epithelium, cloudy swelling of epithelial cells of renal tubules, narrowing of the tubular lumen, contraction of the glomerulus and expansion of space inside the Bowman's capsule were observed in the kidney tissues of fish after exposure. Hepatic lesions in fish exposed to lambda-cyhalothrin were characterized by hypertrophy of hepatocytes, cloudy degeneration, congestion, karyolysis, karyohexis, dilatation of sinusoids and focal necrosis. The intestinal lesions included infiltration of eosinophils into the lamina propria and atrophy of epithelial cells. The present study proves its toxic potential in terms of the damages induced by lambda-cyhalothrin in organ level. In natural condition lambda-cyhalothrin will be less than the present study, but continuous usage of the pesticide might lead to the concentration that was used in the experimental condition.