Action of estradiol on the hermaphroditism induced by testicular graft in the female chick embryo

Abstract

Estradiol administered to female chick embryos bearing an embryonic testicular implant inhibits the activity of the graft on both gonads and Müllerian ducts of the host. In female embryos, an implant alone induces regression of Müllerian ducts and various degrees of gonadal hermaphroditism increasing from atrophy only (Type1) to right testis and left ovary (Type 2), right testis and left ovotestis (Type3), or two atrophic testes (Type 4) corresponding to total sexual inversion. In implanted females, estradiol prevents the development of hermaphroditism (Types 2–3–4), since only Type 1 embryos are obtained, and diminishes the influence of the testicular graft on the regression of Müllerian ducts. The action of estrogen can be explained by an inhibition of the secretion of the “antiMüllerian hormone” by the grafted testis, the hormone responsible for the Müllerian duct regression and for the induction of testes from the host's gonad anlagen. A similar mechanism could explain the intersexuality induced by estrogens in genetically male chick embryo.