The ovaries are female reproductive organs that are akin to the testes in men. They produce the ova (eggs) that, when fertilized, will develop into a fetus; they also generate the female sex hormones estrogen and progesterone. There are two ovaries, each of which is located within the pelvic region beside the uterus (womb).
The ovaries are oval-shaped and are approximately 1 1/2 inches in length. They are pinkish-gray in color and have an uneven surface. The ovaries are connected to the uterus by the fallopian tubes, or oviducts, which carry the eggs into the uterine cavity. Each ovary contains numerous Graafian follicles, egg-containing tubes that grow and develop between puberty, sexual maturation, and menopause, when the monthly menstrual cycle stops. When a woman is fertile, each month a Graafian follicle travels to the surface of the ovary, bursts, and releases an egg and its fluid contents into a fallopian tube.
The Graafian follicles are fixed in a network of supporting tissue (stroma) and blood vessels. They are covered by a clear, smooth, plasma-like membrane that develops from the peritoneumlining of the abdominal cavity. Also within the ovaries are small numbers of corpus luteathe remains of Graafian follicles that have released an egg and are in the process of being reabsorbed by ovarian tissue. Each month the corpus luteum (the scar tissue of a Graafian follicle) is responsible for the production of progesterone. Progesterone is the pregnancy hormone that readies the lining of the uterus for the arrival of a fertilized egg.
During the first half of a woman's menstrual cycleabout 2 weeks before ovulation, an egg is released. The hypothalamus in the brain sends a hormonal signal to the pituitary gland to release follicle-stimulating hormone (FSH) into the bloodstream. When the blood-borne FSH reaches the ovaries, it spurs the Graafian follicles to grow and produce estrogen. Additional estrogen is made by hormone-producing tissue within the stroma. One Graafian follicle in an ovary begins to outgrow the other follicles while the estrogen level is increasing.
Meanwhile, once the estrogen level has peaked, the pituitary gland stops the output of FSH and begins to release luteinizing hormone (LH). The LH causes the Graafian follicle to bubble out on the outside of the ovary, burst, and eject its egg into the fallopian tube. This process of ovulation occurs on or about the 14th day of the menstrual cycle. The ovulated egg travels through the fallopian tube for 5 to 7 days, after which it is released into the uterus.
Connective Tissue & the Ovaries
The ovaries are held in place by bands of fibrous tissue known as ligaments. The ligament of the ovary is a rounded cord that extends from the upper uterus to the lower, inner region of the ovary. The fimbria ovarica are fringe-like tissues that attach the ovaries to the fallopian tubes. The round ligaments are two cords, 4 to 5 inches in length, that connect with layers of the broad ligament (ligament that attaches to each side of the pelvic wall to support the uterus) in front of and below the fallopian tubes.
Blood Vessels, Nerves & the Ovaries
The ovarian arteries, which are offshoots of the abdominal aorta, furnish the ovaries and fallopian tubes with blood. They enter the ovary via an attached border, or hilus. The ovarian veins parallel the route of the arteries, forming a tangled network in the broad ligament known as the pampiniform plexus.
The nerves that supply the ovaries are branches of the inferior hypogastric nerve, the pelvic plexus (network), the ovarian plexus, and uterine nerves within the fallopian tubes.