Abstract

Objective: Present study was aimed to study the cytopathological effects of almix herbicide in Indian freshwater teleost, Oreochromis niloticus (Linn.) both under field and laboratory exposure.

Methods: O. niloticus (Linn.) was exposed to almix herbicide at sublethal concentrations of 8 g/acre and 66.67 mg/L under field and laboratory conditions respectively for 30 days. Field experiment was performed in cage, submerged in the field pond. Cytopathological study both through light and electron microscopic (scanning electron microscopy and transmission electron microscopy) observations were based on gill, liver and kidney.

Results: Histopathological observations revealed hypertrophy and proliferation in gill epithelium, curling and fusion of secondary gill lamellae (SGL), distortion in chloride and pillar cells under laboratory experiment. Scanning electron microscopy displayed severe loss of normal array of concentric microridges, swelling of microridges, damage in epithelial cells and appearance of vacuoles on the stratified epithelium, while loss of regular pattern of microridges were observed under field condition. Transmission electron microscopic study of gill showed severe damages which included degenerative changes in mitochondria, cellular vacuolation, damage in tubule vascular system, presence of lipid droplets, elongated nucleus, but in case of field experiment dilated mitochondria and cytoplasmic vacuolation were more prominent. Degenerative hepatopancreas, necrosis in hepatocytes, severe cytoplasmic vacuolation and disarrangement of hepatic cords in liver of O. niloticus were prominent seen under light microscopy in the laboratory condition, but in field condition elongated hepatocytes with increased nuclei and vacuolation in cytoplasm of hepatocytes were prominent, while TEM study showed degeneration in mitochondria, dilation in rough endoplasmic reticulum, damage in nucleus and appearance of cytoplasmic vacuolation in hepatocytes under laboratory condition. In kidney, degenerative changes in PCT and DCT, shrinkage of glomerulus, vacuolation in the haematopoietic tissues and excess fat deposition were notable changes. In TEM study necrosis in nucleus, severe vacuolation, appearance of endoplasmic reticulum as whorl pattern, degeneration in mitochondria in kidney were serious after almix exposure.

Conclusion: Present study claimed the more profound responses under laboratory condition compared to field and different significant marked changes in these two conditions were prominent. Therefore, these responses in gill, liver and kidney of O. niloticus could be considered as potential of exposure of agrochemicals.

Keywords: Almix; Cytopathology; Chronic exposure; Gill; Liver; Kidney; O. niloticus