Ovary

Ovary, in anatomy, organ of female animals, including humans, that produces reproductive cells called eggs, or ova (see Reproductive System). In humans they are oblong, flattened, ductless glands, about 3.8 cm (1.5 in) long, on either side of the uterus, to which they are connected by the Fallopian tubes. Each ovary is composed of two portions: an external, or cortical portion, and a deep, medullary portion. The cortical portion in the adult contains an enormous number of follicles, or sacs, varying in size: these contain the ova, the female reproductive cells. In each menstrual cycle one of the follicles enlarges and begins to secrete elevated levels of oestrogen. It is then known as a Graafian follicle, from which the ovum will be shed during ovulation in mid-cycle. The ovary secretes hormones that, together with secretions from the pituitary gland, contribute to secondary female sexual characteristics and also regulate menstruation. The union of the male sperm cell with the ovum, usually in the Fallopian tube, results in fertilization.

The ovary may be the site of acute and chronic inflammation; this may arise from injuries during labour, operations in the pelvic area, or gonorrheal infection spreading from the vagina. The ovary also may be affected by several varieties of neoplasms (tumours). Ovarian cysts are fluidic enlargements of one or more Graafian follicles and may reach an enormous size. Other growths, of a solid nature, are known as dermoid cysts, and often contain hair and teeth. These enlargements, although usually benign, occasionally prove to be cancerous (see Cancer). For a discussion of ovaries in plants, see Flower; Fruit; Ovule; Hormone Replacement Therapy.