Histopathological Effects of Fonofos on Gills of Zebrafish (Danio rerio)

Organophosphate pesticides are commonly used to increase agricultural efficiency worldwide. However, it has been proved that these chemicals generally do not show target specificity and non-target vertebrate organisms are adversely affected by pesticide exposure. The aim of the present study was to examine the potential harmful effects of fonofos, an organophosphate insecticide, on the gill tissues of zebrafish ( Danio rerio ). Adult zebrafish were exposed to 1, 2 and 4 mg/L fonofos for 96 hours. Gill tissues were removed, fixed with Bouin’s fluid and embedded in paraffin. 5 μm serial sections were stained with hematoxylin-eosin, Gomori trichrome or periodic acid-Schiff. Samples were investigated by light microscopy and histological alterations were compared with the 0.1% dimethyl sulfoxide (DMSO) exposed solvent control samples. Fonofos caused epithelial lifting, curling of secondary lamellae, desquamation, epithelial hyperplasia, and lamellar fusion in the gills. Gills showed distinct histopathological changes through fonofos exposure. It was determined that fonofos is a threat to non-target organisms living in aquatic ecosystems