testosterone plays a primary role in driving the fetal gonad towards becoming testes and the subsequent development of male genitalia. Jost discovered that if he removed the male embryonic gonads early in development, the fetus failed to grow a penis and scrotum and developed a vagina and clitoris instead. Removing the developing ovaries of a fetal female, on the other hand, did not obviously impact her sexual development. Oviducts, uterus, cervix and vagina all developed in an apparently automatic fashion without the need of her embryonic ovaries or their hormones to direct them.
