Each ovary contains approximately 200,000 eggs of which 400 are shed during the fertility cycles. The release of these eggs are part of the process that can lead to pregnancy and are responsible for the monthly cycling of a woman's hormones and the shedding of the lining of the uterus commonly called the "period" or menstruation.

The ovaries are also responsible for producing the female hormones estrogen and progesterone.

Estrogen is responsible for many activities that go on in a woman's body, including the development of the breast tissue. It also helps increase bone growth at the time of puberty and helps to prepare the pelvis for childbearing. It helps in the monitoring of calcium and phosphate use and helps to increase the amount of protein our bodies use. It can cause a slight increase in the metabolic rate and can increase the amount of salt we retain.

Progesterone helps to develop the milk producing cells in the breast. The milk is produced by the action of the hormone known as prolactin. Progesterone can also increase the amount of salt and water retained by the body.