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Abstract
Heavy metal concentrations of mercury and the associated structural deformities in the gills, muscles, intestine, brainand liverof Asian sea bass, Latescalcarifer were observed for sublethal toxicity studies.Cytopathological alterations in gill tissuesdisplayed oedema of epithelial cells, ballooning dilation, partial epithelial lifting, and damaged pillar cells; the muscle displayed shortening of muscle bundles, oedema and necrosis, atrophy of muscle bundles, and vacuolar degeneration in muscle bundles;the intestine showed deformities in degeneration in cup villi, atrophy of muscularis layer, inflammation in mucosa and submucosa, and degeneration in submucosa, serosa, and tunica serosa. In the brain,the pathology was observed as necrosis of the brain cells, degeneration of nerve cells, atrophy, and dissolution of nissel bodies. The liver tissue showed degenerative hepatocytes and nuclear hypertrophy. The present study demonstrated that all the treated body tissues exhibited significant damage with response; among the body organs, the liver and brain are important target organs for mercury toxicity in L. calcarifer, which suggest that biomarkers are useful in assessing the model organism for toxicity studies.
Keywords:Latescalcarifer, mercury, cytopathology
Introduction
Mercury has no known metabolic functions in human beings and therefore even low concentrations in the body may be measured to be potentially harmful. Mercury in fish and seafood occurs mainly as methyl mercury and partly as inorganic mercury bound to organic molecules. Mercury compounds exert their action by altering the membrane structure, and thus seriously affect the permeability character of cell types. The inability of mercury - exposed fish to maintain its ionic balance could be attributed either to a decreased uptake of ions via gills or to an increased loss of ions via gills or kidney.Histopathology refers to the microscopic examination of tissues in order to study the manifestations of disease or damage. Toxicological histopathology gives useful data regarding changes induced by chemicals in pesticides at the tissue and cellular levels. All tissues and organs in the body of an animal are considered potential targets for the toxic effects of any chemical compound, for example pesticides. A histopathological assessment clarifies the nature of tissue alteration and the extent of damage indicating the toxic nature of the compound. The advantages of using cytopathological biomarkers in environmental monitoring are manifold. Biomarkers allow examining specific target organs, such as gills, kidney and liver,...