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[L. ovarium, ovary]
One of two almond-shaped glands in the female that produces the reproductive cell, the ovum, and three hormones: estrogen, progesterone, and inhibin. The ovaries lie in the fossa ovarica on either side of the pelvic cavity, attached to the uterus by the utero-ovarian ligament, and close to the fimbria of the fallopian tube. Each ovary is about 4 cm long, 2 cm wide, and 8 mm thick and is attached to the broad ligament by the mesovarium and to the side of the pelvis by the suspensory ligament. At menarche, the surface of the ovary is smooth; at menopause, the rupture and atrophy of follicles make it markedly pitted.
Each ovary consists of two parts. The outer portion (cortex) encloses a central medulla, which consists of a stroma of connective tissue containing nerves, blood and lymphatic vessels, and some smooth muscle tissue at region of hilus. The cortex consists principally of follicles in various stages of development (primary, growing, and mature or graafian). Its surface is covered by a single layer of cells, the germinal epithelium, beneath which is a layer of dense connective tissue, the tunica albuginea. Each of the 400,000 follicles present in the ovaries at birth has the potential for maturity, but fewer than 600 mature during a woman's reproductive years (usually one per cycle). Other structures (corpus luteum, corpus albicans) may be present. The blood supply is mainly derived from the ovarian artery, which reaches the ovary through the infundibulopelvic ligament.
SEE: fertilization for illus.; SEE: oogenesis for illus
The functional activity of the ovary is controlled primarily by gonadotropins of the hypophysis, follicle-stimulating hormone (FSH), and luteinizing hormone (LH). The hormones produced are estrogen, progesterone, and inhibin. Estrogen is secreted by the developing follicle and by the corpus luteum if the ovum is fertilized. Estrogen stimulates development of the secondary sexual characteristics, growth of the mammary glands, and growth of the endometrium for possible implantation of a fertilized egg. Progesterone is secreted by the corpus luteum; it contributes to growth of the endometrium and mammary glands. Inhibin is secreted by cells of the follicle and the corpus luteum; it decreases the secretion of FSH.