Ultrastructural biomarker responses in gill tissues of Cirrhinus mrigala (Hamilton, 1822) through SEM after exposure to zinc sulphate

Abstract

Zinc is an essential trace element for the normal development and metabolism of living organisms. Mrigal (Cirrhinus mrigala) was exposed to sub-lethal concentrations 9.3, 13.2, 18.6 and 31 mg/l of zinc sulphate for 30 days and ultrastructural alterations were observed in the gills. The gill epithelium of the untreated group showed a normal architecture while zinc- treated groups showed certain marked changes in gill tissues such as fusion of secondary lamellae, edema, disruption of gill epithelium, hypertrophy, hyperplasia, broken and swollen microridges, broken tips and upliftment of gill rakers, heavy exudation of mucous and disorganization of secondary lamellae. These changes demonstrate the morphological responses of the fish when exposed to zinc sulphate. The present study clearly shows that gills are an important target organ for zinc toxicity in C. mrigala.

Keywords

• Mrigal
• Gills
• Ultrastructure
• Hypertrophy
• Secondary lamellae
• Hyperplasia