Copper is a trace element necessary for the normal growth and metabolism of living organisms. If exceeds its limit it becomes pollutant and causes pathological effects. Asian sea bass (Lates calcarifer) was exposed to sublethal concentrations of copper for 28 days and histopathological alterations were noticed in the gill, liver, muscle and intestine. Epithelial necrosis, hypertrophy, rupture of gill epithelium and haemorrhage at primary lamellae were observed after 7 days of exposure. Lifting of epithelium, oedema and fusion of adjacent secondary lamellae were conspicuous at 28 days of exposure. The experimental liver tissue showed reduction in the size of hepatocytes, vacuolisation, and hypertrophy. The intestine displayed fused microvilli, sloughing of mucus membrane and swollen cells. Muscle bundles with severe oedema and their thickening and separation were more pronounced in sublethal treatment of copper in the muscle. Several histopathological changes observed in various fish organs would serve a useful purpose in evaluating the toxic effects of copper. The present study clearly demonstrated that all the treated body organs exhibited significant damage with response; amongst the body organs the liver is an important target organ for copper toxicity in L. calcarifer and this species could be possibly used as a model organism for toxicity studies.
Surface ultrastructure of the gill and liver of 3-month-old Asian sea bass, Lates calcarifer, after copper exposure, was investigated by scanning electron microscopy (SEM). Fish samples were exposed to copper concentrations of 6.83 and 13.66 ppm (sublethal) for 28 days with parallel untreated control. These structures showed structural modifications in both low and high concentrations of copper exposure. Oedema, hyperplasia, desquamation, necrosis, epithelial lifting, lamellar fusion, collapsed secondary lamellae, curling of secondary lamellae and aneurism in the secondary lamellae were observed in gill tissues exposed to copper. Hepatic lesions related to cloudy swelling of hepatocytes, congestion, vacuolar degeneration, dilation of sinusoids and nuclear hypertrophy were evident in the exposed sea bass liver tissue.
-Bioaccumulation and ultrastructural alterations in gill and liver tissues of 3-month old Asian sea bass, Lates calcarifer, in response to copper were studied by transmission electron microscopy (TEM). Fishes were exposed to two sublethal concentrations of copper (6.83 ppm and 13.66 ppm) for a period of 28 days. Accumulation of copper were higher in the liver followed by gills. The damaging effects of the histoarchitecture of gill tissues in coper-exposed sea bass were hypertrophy and hyperplasia of epithelial cells, severe oedema, telangiectasia and secondary lamellar fusion. In addition extensive vasodilation with stretching and necrosis of pillar cells were also noted. The liver showed hydropic swelling of hepatocytes with nuclear pyknosis and chromatin condensation. Blood congestion in sinusoids and accumulations of lipid droplets in the hepatocytes at higher concentrations were observed.
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