Figure 6. Development of male external genitalia in the human embryo. At the 8-wk-end embryo the external genitalia of both sexes are identical and have the capacity to differentiate in both directions: male or female. DHT stimulates growth of the genital tubercle and induces fusion of urethral folds and labioscrotal swellings. It also inhibits growth of the vesicovaginal septum, preventing development of the vagina.