The menstrual cycle is the recurring cycle of physiological changes that occur in females and other primates of reproductive age. The menstrual cycle results from the coordinated actions of hormones made by the brain and pituitary gland acting on the ovaries and uterus in order to coordinate ovulation and fertilization. Hormones like FSH, LH, and activin made in the pituitary gland respond to and control the release of estrogen, progesterone, and inhibin by the ovary. These hormones then control and prepare the uterus for an egg, if fertilized. If the egg that is released each month is not fertilized, the uterine wall is shed. The shedding of the uterine wall is known as menstruation and is the more obvious external evidence of a functional reproductive cycle.