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:
Alpha-Melanocyte-stimulating hormone melanotan II, the former of which being in phase-III clinical trials in the United States. Bremelanotide, another analogue of α-MSH, is currently under development not as a photoprotective agent, but instead for the treatment of sexual dysfunction. All of these drugs have significantly greater potencies than α-MSH, along with improved pharmacokinetics and distinctive selectivity profiles. Alpha-Melanocyte-stimulating hormone α-Melanocyte-stimulating hormone (α-MSH) is an endogenous peptide hormone and neuropeptide of the melanocortin family, with a tridecapeptide structure and the amino acid sequence Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val-NH. It is the most important of the melanocyte-stimulating hormones (MSHs) (also known as melanotropins) in stimulating melanogenesis, a process