Sexual differentiation in humans development can only occur when the fetal testis secretes key hormones at a critical period in early gestation. The testes begin to secrete three hormones that influence the male internal and external genitalia: they secrete anti-müllerian hormone (AMH), testosterone, and dihydrotestosterone (DHT). Anti-müllerian hormone causes the paramesonephric ducts to regress. Testosterone converts the mesonephric ducts into male accessory structures, including the epididymis, vas deferens, and seminal vesicle. Testosterone will also control the descending of the testes from the abdomen into the scrotum. Many other genes found on other autosomes, including"WT-1", "SOX9", "SF-1" also play a role in gonadal development. Females:
Male lactation where male lactation occurs and it is not well understood what evolutionary factors control the development of this trait. The phenomenon of male lactation occurs in some species, notably the Dayak fruit bat ("Dyacopterus spadiceus"), and the lactating males may assist in the nursing of their infants. In addition, male goats are known to lactate on occasion. Human male breastfeeding is possible, but production of the hormone prolactin is necessary to induce lactation, so male lactation does not occur under normal conditions. Domperidone is a drug that can be used to increase lactation. Male lactation has also been seen during