A hormone that plays a role in controlling sperm formation and the maturation of ovarian follicles by acting on the anterior pituitary to reduce secretion of follicle-stimulating hormone (FSH). In males, inhibin is produced by Sertoli cells in the testis, whereas in females it is secreted by the granulosa cells that surround the ovum in a developing follicle. In both cases, the inhibin acts as negative feedback mechanism to regulate FSH levels.