Histopathological analysis of sublethal toxicity induced by lead nitrate to the accessory respiratory organs of the air-breathing teleost, Heteropneustes fossilis (Bloch)

Abstract

Toxicity of sublethal concentration of lead nitrate solution (92.5 ppm: 10 % of 96 h LC50) causes severe damages to the air-breathing organs (ABO) of Heteropneustes fossilis leading to its asphyxiation and death. The prominent damages included haemorrhage into the lumen following necrosis and sloughing of the respiratory epithelium. The RBCs lysed, degenerated and often got accumulated in the lumen causing their decreased density. A large number of blood vessels (BV) appeared in the sub-epithelial connective tissue. Frequently, individual cells from the inner lining of these BV showed pinocytosis and shed into the lumen. Periodic fluctuations in the density of the mucous cells which start staining for sulphated mucopolysaccharides were also observed at various stages of exposure.