Histopathological and Ultrastructure Alteration Of Gills in Common Carp (Cyprinuscarpio L.) After Long Time Exposure to Zinc Oxide Nano particles .

Abstract

This study aimed to assess the toxicity and severity of zinc oxide nanoparticle (ZnO-NPs) in the tissues of gills. Therefore, carp fish (Cyprinus carpio) were subjected to sub-lethal concentration of (ZnO-NPs) 9mg/l for periods of (7, 14, 21, 28, 35, 42) days that led to a histopathological and ultrastructural alteration in gills tissue. Microscopic examination showed the occurrence of bleeding and the pyramidal form (clump shape) of the epithelial cells lining the secondary gill filament after the lapse of 7 and 14 days after the treatment, and hyperplasia in mucus cells with hypertrophy of pillar cells at 28 days of treatment. At day 42, the lesions were characterized by basement thickening in the secondary gill filament with edema and vacuolar degeneration of pillar cells. While ultrastructural examination showed the presence of cloudy swelling of chloride cells and condensation of micro organelles at seven days of exposure increased with increasing duration of exposure and, therefore, at day 14 of exposure to the (ZnO-NPs). The electron microscope examination showed a thickening of blood vessels wall, hyperplasia of mucous cells with vacuolar degeneration of chloride cells. Ultra-structural changes in gills tissue of fish that exposed to N-ZnO for 42 days revealed microvilli and adhesion of micro ridge with degeneration of epithelial cells lining the secondary gill filaments. In conclusion, ZnO-NPs are toxic in a concentration of 9mg/l in a common carp (Cyprinus carpio), that lead to histopathological and ultra-structure alteration in gills and there was a positive relationship between the severity of lesions and time of exposure (7, 14, 21, 28,35 and42) days.

Keywords

• zinc oxide nanoparticles
• gill
• ultrastructure
• cyprinus carpio