GONADOTROPHIC EFFECTS OF EXOGENOUS SEX HORMONES ON THE TESTES OF SPARROWS¹

Abstract

THE MECHANISM by which exogenous androgens act to maintain spermatogenesis or to cause spermatogenesis to go to completion in the regressed testis is not understood. It would seem that the androgen does not act through the hypophysis in mammals since it maintains spermatogenesis in the hypophysectomized rat (Nelson, 1941; Walch, Cuyler and McCullach, 1934) and stimulates spermatogenesis in ground squirrels hypophysectomized during the non-breeding season (Wells, 1942). Until the present investigation was completed, the only evidence that androgens stimulate the bird testis had been presented by Chu (1940) who found testis stimulation in 3 hypophysectomized pigeons. On the other hand, it had been reported for fowl (Morató-Manaro, Albrieux and Bruño, 1938) and Starlings (Burger, 1944) that androgen caused regression of the testes. However, recently androgen was shown to cause an increase in the size of the dove testis (Lahr and Riddle, 1944) and to stimulate spermatogenesis in Starling testes which had reached the spermatocyte stage before treatment was begun (Burger, 1945).