Effects of estrogen, progesterone, and testosterone on the pituitary and ovary of catfish, <i>Heteropneustes fossilis</i> (Bloch)

Abstract

Abstract Estradiol benzoate (EB), testosterone propionate (TP) and progesterone have been administered orally over 45 days during the late preparatory period to intact female catfish showing ovarian recrudescence. EB or TP treatment brings about a reduction in the size and number of basophils in the pituitary, and inhibition of vitellogenesis in the ovaries. Progesterone administration causes partial ovarian regression without significantly altering pituitary cytology. The sexually dimorphic urogenital papilla which is inconspicuous and nonmuscular in the female is unaffected by hypophysectomy and/or EB treatment. TP induces complete masculinization of the female papilla, whereas progesterone is only marginally effective. EB injections over 15 days to intact catfish having ovaries containing yolk laden oocytes induce significant reduction in the number of pituitary basophils and extensive follicular atresia in the ovaries. Administration of EB to hypophysectomized catfish inhibits hypertrophy of the granulosa cells surrounding the yolky oocytes and thus delays the impending follicular atresia. The significance of these findings is discussed.