ovary

The ovary is the female gonad, the paired almond-sized organ that does two jobs at once: it stores and releases eggs, and it acts as an endocrine gland producing the major female sex hormones. Picture it as both a seed vault and a hormone factory housed in the same small structure on each side of the pelvis.

Each ovary contains thousands of ovarian follicles, each a tiny fluid-filled sac sheltering one immature egg surrounded by hormone-making cells. A woman is born with her entire lifetime supply of eggs; this pool steadily declines with age. Across each menstrual cycle, a cohort of follicles grows under the pituitary hormones FSH and LH, usually one matures fully and releases its egg at ovulation, and the remnant becomes the corpus luteum.

As an endocrine organ the ovary secretes estradiol and progesterone (and smaller amounts of androgens and inhibin), participating in the hypothalamic-pituitary-gonadal axis through feedback to the brain. A key caveat is finiteness: unlike the testis, which makes new sperm continuously, the ovary cannot generate new eggs, so its reproductive and much of its hormonal function naturally winds down at menopause.