Ovaries are gonads that release eggs and rewrite hormones
In humans each ovary is a gonad: it ripens and releases egg cells while secreting sex hormones and inhibin that brakes pituitary FSH. Paired glands flank the uterus, linked by fallopian tubes and steadied by ovarian and suspensory ligaments inside the pelvic bowl.
The name comes from the Latin ovarium, meaning egg, and the organ has two jobs. As a gonad it makes sex hormones, and it also governs how egg cells mature and are released. Its follicles, the small sacs that each hold an oocyte, secrete inhibin, a hormone that damps the effect of follicle-stimulating hormone from the anterior pituitary. The ovary changes through many stages from before birth to menopause, and much of its structure is shared with other mammals and vertebrates.
There are two, one on each side of the uterus, linked to it by the fallopian tubes. At puberty each is roughly 3 cm long, 1.5 cm wide and 1 cm thick. It rests in the ovarian fossa, a hollow of about 4 by 3 by 2 cm in the side wall of the pelvis, with the external iliac vessels above it, the obliterated umbilical artery in front and the ureter behind. A fibrous cord, the ovarian ligament, ties it to the uterus, and the suspensory ligament, an extension of the broad ligament, tethers it to the body wall. The fold of broad ligament that holds it is the mesovarium.
Inside, a dense capsule called the tunica albuginea encloses an outer cortex and an inner medulla, and a skin of cuboidal to columnar cells, the germinal epithelium, covers the surface. The boundary between cortex and medulla is blurry, but follicles normally live in the cortex, not the core.
The medulla is richly supplied with blood and lymph vessels, immune cells and nerves, and forms the hilum where the ovarian ligament attaches and vessels enter. The cortex holds many primary oocytes, each in its own follicle. After puberty these follicles mature in stages, gaining layers such as granulosa cells, the zona pellucida and the theca, plus follicular fluid. Once ovulation releases the egg, what remains of the follicle becomes the corpus luteum.
Source: Ovary
