Histopathological Studies on Tilapia zillii and Solea vulgaris from Lake Qarun, Egypt

Abstract

Lake Qarun is an inland lake occupies the lowest part of El-Faiyoum depression. It receives large amounts of contaminated drainage water from Faiyoum Province. The study was conducted to investigate the histological structures of the muscles, liver, gills, kidney and intestine of Tilapia zillii and Solea vulgaris obtained from Lake Qarun, Egypt during summer 2007 and winter 2008. Several histological alterations were observed in the muscles of both fish, including degeneration in muscle bundles with focal areas of necrosis, atrophy of muscle bundles and edema between muscle bundles. The liver showed vacuolar degeneration in the hepatocytes, focal areas of necrosis and fibrosis, aggregations of inflammatory cells between the hepatocytes, dilation and congestion in blood sinusoids and thrombosis formation in the central veins. In the gills, the pathological alterations included proliferative, degenerative and necrotic changes in the epithelium of gil l filaments and secondary lamellae, edema in secondary lamellae, dilation and congestion in blood vessels of gill filaments and mucous cells proliferation. The kidney showed vacuolar degeneration in the epithelium of renal tubules, focal areas of necrosis, haemorrhage and haemosiderin between the renal tubules and edema in Bowman's capsules with atrophy in the glomeruli. In the intestine, degenerative and necrotic changes in submucosa and mucosa with edema between them, dilation in blood vessels of serosa and atrophy in th e muscularis and submucosa are noticed. It was concluded that the environmental contamination of Lake Qarun induced several histopathological alterations in the tissues of T. zillii and S. vulgaris.