The ovaries, uterine tubes, and uterus of the sexually mature female undergo marked structural and functional changes related to neural activity and changes in hormone levels during each menstrual cycle and during pregnancy. These mechanisms also regulate the early development of the female reproductive system. The initiation of the menstrual cycle, referred to as the menarche, occurs in females between 9 and 14 years of age (the mean age of menarche is 12.7 years) and marks the end of puberty and the beginning of the reproductive life span. During this phase of life, the menstrual cycle averages about 28 to 30 days in length. Between 45 and 55 years of age (the mean age is 51.4 years), the menstrual cycle becomes infrequent and eventually ceases. This change in reproductive function is referred to as the menopause or climacterium (commonly called the “change of life”). The ovaries cease their reproductive function of producing oocytes and their endocrine function of producing hormones that regulate reproductive activity. Other organs (e.g., vagina and mammary glands) show varying degrees of reduced function, particularly secretory activity.
Production of gametes and steroid hormones are the two major functions of the ovary.
The ovaries have two interrelated functions: gametogenesis (the production of gametes) and steroidogenesis (the production of steroids). In women, the production of gametes is called oogenesis. Developing gametes are called oocytes; mature gametes are called ova.
Two major groups of steroid hormones—estrogens and progestogens—are secreted by the ovaries.
 Estrogens promote the growth and maturation of internal and external sex organs and are responsible for the female sex characteristics that develop at puberty. Estrogens also act on mammary glands to promote breast development by stimulating ductal and stromal growth and accumulation of adipose tissue.
 Progestogens prepare the internal sex organs, mainly the uterus, for pregnancy by promoting secretory changes in the endometrium (discussed in the section on cyclic changes in the endometrium). Progestogens also prepare the mammary gland for lactation by promoting lobular proliferation.
FIGURE 23.2 • Schematic drawing of a section through the ovary. This drawing shows stages of follicular development from the early primary follicle to the mature (Graafian) follicle. The maturation of the follicles occurs in the direction of the arrow. Changes in the follicle after ovulation lead to development of the corpus luteum and eventually the corpus albicans. Note the highly coiled blood vessels in the hilum and medulla of the ovary.
Both hormones play an important role in the menstrual cycle by preparing the uterus for implantation of a fertilized ovum. If implantation does not occur, the endometrium of the uterus degenerates and menstruation follows.
In nulliparas (women who have not borne children), the ovaries are paired, almond-shaped, pinkish white structures measuring about 3 cm in length, 1.5 cm in width, and 1 cm in thickness. Each ovary is attached to the posterior surface of the broad ligament by a peritoneal fold, the mesovarium (see Fig. 23.1). The superior (or tubal) pole of the ovary is attached to the pelvic wall by the suspensory ligament of the ovary, which carries the ovarian vessels and nerves. The inferior (or uterine) pole is attached to the uterus by the ovarian ligament. This ligament is a remnant of the gubernaculum, the embryonic fibrous cord that attaches the developing gonad to the floor of the pelvis. Before puberty, the surface of the ovary is smooth, but during reproductive life it becomes progressively scarred and irregular because of repeated ovulations. In postmenopausal women, the ovaries are about one-fourth the size observed during the reproductive period.
The ovary is composed of a cortex and a medulla.