Follicle-stimulating hormone (FSH) is a hormone synthesized and secreted by gonadotropes in the anterior pituitary gland in mammals. In the ovary, follicle-stimulating hormone FSH stimulates the growth of immature Graafian follicles to maturation. As the follicle grows it releases inhibin, which shuts off the FSH production. In men, FSH enhances the production of androgen-binding protein by the Sertoli cells of the testes and is critical for spermatogenesis. FSH is a major constituent of fertility drugs, used to treat failure of ovulation and decreased sperm production.