Masculinization of the female fetus by androgens given to the mother is well established. The purpose of this study is to determine whether feminization in the male infant occurs when estrogens are administered in pregnancy.
Jones and Wilkins 1 have summarized recent concepts of the development of sexual structures. Experimental observations on a variety of mammals and marsupials were performed during the indifferent or bisexual phase of sexual differentiation.2 At this point the embryo has both wolffian and müllerian ducts. The external genitalia are underdeveloped and are capable of development in either direction, male or female. If gonadectomy is performed prior to a critical time in the male or female animals the wolffian ducts atrophy; the müllerian ducts and external genitalia develop into female structures. In other words, female development is the asexual norm. There is a parallel in the human with gonadal agenesis.
The genetic constitution determines whether