During their reproductive years, nonpregnant females usually experience a cyclical sequence of changes in their ovaries and uterus. Each cycle takes about one month and involves both oogenesis, the process of formation and development of the egg or ovum, and preparation of the uterus to receive a fertilized ovum. Hormones secreted by the hypothalamus, anterior pituitary gland and ovaries control the principal events. The ovarian cycle is a series of events in the ovaries that occur during and after the maturation of the oocyte. The uterine (menstrual) cycle is a concurrent series of changes in the endometrium of the uterus to prepare it for the arrival of a fertilized ovum that will develop in the uterus until birth. If fertilization does not occur, the stratum functionalis of the endometrium is shed. The general term female reproductive cycle encompasses the ovarian...