Histology of gonads in Oreochromis niloticus (Trewavas) fed pawpaw (Carica papaya) seed meal diets.

Pawpaw (Carica papaya) seed meal (PSM) was added to a basal diet 350g crude protein and 18.5MJ gross energy/kg diet) at 0, 0.5, 1.0, 1.5 or 2.0 g/kg diets and fed to O eoch omis niloticus for 60 days to evaluate the effects on histology of the gonads. O. niloticus fed 0g PSM/kg diet showed normal testicular tissues and no lesions were observed. Fish fed 0.5g PSM/kg diet showed slight increase in interstitial cells. Fish fed 1.0g PSM/kg diet showed swollen sperm cells nuclei, increased interstitial cells and focal necrosis. Fish fed 1.5g PSM/kg diet exhibited atrophy of seminiferous tubules and in fish fed 2.0g PSM/kg diet, there were severe pathological changes as disintegration of sperm cells and necrosis of the testicular cells. Ovaries in fish fed with control diet (0g PSM/kg diet) showed normal ovary histology. No pathological lesions were observed. Typical bilateral lobes of the ovaries were evident and with normal olive green colour of ovaries. Fish fed 1.0g PSM/kg diet revealed ovarian colour change, hydropic degeneration, ruptured follicle, granulomatous inflammation in the insterstitium and necrosis. Ovaries in fish fed 2.0g PSM/kg diet showed severe atretic follicle. Histology of gonads in O. niloticus fed high dietary PSM revealed that pawpaw seeds may be effective as sterility-inducing agents. r r