Histopathological and ultrastructural changes in the gill and liver of fresh water fi sh Channa punctatus exposed to sodium arsenite

Abstract

Arsenic, is one of the most important and concerned global environmental toxicants. Correlations have been found between chronic arsenic poisoning and many severe health effects including cancers, hypertension and ischemic heart disease etc. However, the proper understanding of the role of arsenic in the cause of these diseases is still limited. In this work, we studied the toxicity effect of sodium arsenite in the gill and liver tissues of fresh water fish Channa punctatus and for the first time observed the histopathological as well as surface ultrastructural changes on it. The liver and gill tissues of Channa punctatus were exposed to sub-lethal (12 ppm: parts per million) concentration of sodium arsenite (NaAs02) for 96 hours. The histopathological effects of sodium arsenite on the liver and gill tissues were studied by light microscopy. The surface ultrastructural changes on the same tissues were investigated by scanning electron microscopy (SEM). The results were compared with the normal structure of liver and the gill tissue of a control group of Channa punctatus. Gill tissues exposed to arsenic showed hyperplasia, desquamation, and necrosis of epithelium, epithelial lifting, oedema, lamellar fusion, collapsed secondary lamellae, curling of secondary lamellae and aneurism in the secondary lamellae. Hepatic lesions in the form of cloudy swelling of hepatocytes, congestion, vacoular degeneration, karyolysis, dilation of sinusoids and nuclear hypertrophy were observed in the liver tissue of the exposed group. Thus it has been shown that sodium arsenite can produce significant damage in the ultrastructure of liver and gill tissues. Also the histological and ultrastructural changes on the liver and the gill tissue indicate that arsenic is biologically reactive and gives rise to acute poisoning.