EFFECTS OF GONADOTROPIC HORMONES ON MALE HYPOPHYSECTOMIZED LAKE CHUB, COUESIUS PLUMBEUS

Abstract

In lake chub, Couesius plumbeus, hypophysectomy causes marked regression in the testes, suppresses the mitotic ability of the spermatogonia, completely blocks their transformation into spermatocytes, and affects the normal secretory activity of the lobule boundary cells. Spermatogenesis is largely reinitiated and secretory activity of lobule boundary cells is restored by injections of a partially purified salmon pituitary extract, by mammalian luteinizing hormone, and by crude extracts of whole pituitary of salmon. The gonadotropin responsible for testicular maturation is similar to mammalian luteinizing hormone; a factor like mammalian follicle-stimulating hormone is probably not physiologically active in this fish. Although gonadotropin is primarily responsible for gonadal maturation, other factors such as thyrotropin and somatotropin probably have a stimulatory effect by acting synergistically with the gonadotropin. The paper presents details of a technique for hypophysectomy.