In this investigation, effect of cadmium chloride (25 μg/l) on oogenesis of freshwater prawn, Macrobrachium rosenbergii was studied. In vivo experiments were performed with both intact and eyestalk ablated prawns. The intact, cadmium-exposed prawns exhibited decrease in Gonado Somatic Index (GSI) and ovarian development compared to controls. Whereas, ablated treated ovary showed reduction of yolk material and oocyte membrane thickness at the end of 15 days exposure. Interestingly, the control prawn showed normal cellular architecture of gills, hepatopancreas and ovary with mature oocytes. But, the gills of treated prawns showed lamellar hypertrophy, cuticular dystrophy and irregular arrangement of epithelial cells. Hepatopancreas showed reduction in both tubular diameter and basement membrane thickness. Conspicuously, ovary showed hypertrophied primary oocytes with more vacuoles in intact-treated group. Cadmium had increased gonad inhibiting hormone (GIH) secretion and decreased gonad stimulating hormone (GSH) release as evident with the retardation of gonadal maturation in the intact prawns.
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