Biology of Reproduction, Vol 11, 398-405, Copyright © 1974 by Society for the Study of Reproduction

Effects of Testosterone and Estradiol on the Development of Sexual Characters in Young Rana nigromaculata

¹ Biological Institute, Niigata University, Niigata 950-21, Japan

Testosterone or estradiol, or both were administered to first-year autumn frogs of Rana nigromaculata, and the effects of these hormones on the reproductive tracts and the thumb pad were examined histologically. The Wolffian duct was stimulated remarkably by the injection of testosterone irrespective of sex. The simultaneous application of estradiol induced a more striking response on the Wolffian duct. A remarkable hypertrophy of the Müllerian duct was observed in estradiol-treated frogs. This response was slightly inhibited by the simultaneous injection of testosterone, though the Müllerian duct was somewhat stimulated by the administraton of testosterone alone. Considerable development of the thumb pad was induced by testosterone, and this development was more stimulated by the simultaneous administration of estradiol, though the injection of estradiol alone showed no influence on the development of the thumb pad. Thus, the combined action of sex hormones differed in each target organ.