[Compared action of norethindrone and various steroids on Müller ducts of the female chick embryo].

Treatment of female chick embryo with norethindrone (NET), a potent progesterone-like steroid, caused caudal agenesia and cephalic regression of Mullerian ducts as the normal regression induced by anti-Mullerian-hormone in the male embryo. The comparative study of five other progesterone-like steroids shows that only lynestrenol which is metabolized into NET at least in man, possesses the same properties as NET. The four others, i.e. medroxyprogesterone, medrogestone, norgestrienone and 17 alpha hydroxyprogesterone are only able to induce agenesia, an unspecific property, which was observed with many steroidal hormones, as norethandrolone here studied.