Effects of teleost gonadotropins and their antibodies on gonadal histology in winter flounder

Abstract

The gonadotropic actions of teleost vitellogenic and maturational hormones were studied in flounder hypophysectomized shortly after reinitiation of vitellogenesis and spermatogenesis in August. Maturational hormone alone was able to stimulate formation of yolky oocytes, but vitellogenic hormone required the action of estrogen before it could stimulate production of yolky oocytes. An antiserum to vitellogenic hormone induced atresia of yolky oocytes and lowered the gonadosomatic index in vitellogenic flounder whereas an antiserum to maturational hormone did not affect ovarian histology or gonadosomatic index to any great extent. Preincubation of flounder ovarian sections with vitellogenic hormone, followed by incubation with antiserum to vitellogenic hormone and fluorescein isothiocyanate-labeled goat-anti-rabbit γ-globulin in succession, resulted in immunofluorescence in ooplasm of both large immature and vitellogenic oocytes, and in follicular envelopes of vitellogenic oocytes. Preincubation of ovarian sections with maturational hormone resulted in fluorescence in the interstitial tissue, and the follicular envelopes and the perinuclear regions of yolky oocytes. Maturational hormone stimulated spermatogenesis in hypophysectomized male flounder. The significance of these results in relation to previous studies was discussed.