Histological and Electron Microscopical Observations on Copper Poisoning in the Winter Flounder (Pseudopleuronectes americanus)

Abstract

Effects of high, medium, and low levels of copper on the morphology of winter flounder were investigated using routine histological techniques and electron microscope analyses.High and medium levels of copper resulted in fatty metamorphosis in the liver, necrosis in the kidney, destruction of the hemopoetic tissue, and gross changes in gill architecture. Seven other structures and organs were examined for copper-induced morphological changes but none were found.Light microscope studies showed that low levels of copper caused an extracted appearance in gill lamellae; the epithelial layer appeared vacuolated; the basi-lamellar region was reduced in thickness. Lamellar mucus cells were few compared with control specimens and chloride cells appeared in their stead.Electron microscope study of gill lamella from fish exposed to low levels of copper confirmed vacuolation in the epithelial layer. Also found were myelinlike figures, various membrane-bound vesicles, and apical homogeneous layers of reduced thickness. Increased amounts of particulate matter adhering to the external surface of the epithelial cells were apparent. Chloride cells were found instead of mucus cells.