cadmium induced histopathology in the olfactory epithelium of a snakehead fish, channa punctatus (bloch)

histopathology on the olfactory organ of a snakehead fish, channa punctatus (bloch, 1793) were assessed after exposing the fish to 2.5 mg/l and 5mg/l of cdcl 2 for 15 days, 30 days and 45 days. cellular organization of the epithelium was affected severely with degeneration of sensory and supporting cells and hyperplasia of basal cells and mucous cells. mucous cell proliferation indicates the upregulation of mucous secretion to protect the epithelium from toxic effect of cadmium. the olfactory epithelium was endowed with the multipotent basal cells which differentiate into sensory cells, supporting cells and other cell types of the epithelium during normal cells turn over and in the event of cell death.  however, due to cadmium exposure proliferating basal cells failed to differentiate into normal cells and the undifferentiated proliferated cell formed lump and intraepithelial lesion altering the composition of the entire epithelium. present study indicates that in prolonged exposure to cadmium chloride olfactory functions of the fish might be impaired due to loss of all sensory cells.