and derived from their homologous structures. At 16 weeks post-conception, the genitalia are formed and distinct.

The masculinization of the embryonic reproductive structures occurs as a result of testosterone secreted by the embryonic testes. Testosterone, however, is not the active agent within these organs. Once inside the target cells, testosterone is converted by means of an enzyme called 5?-reductase into the dihydrotestosterone (DHT). DHT mediates the androgen effect in these organs.