The ovaries are part of the female reproductive system. They are located on each side of the uterus in the lower abdominal area. Women have two ovaries that produce eggs, as well as the hormones estrogen and progesterone. Sometimes, a fluid-filled sac called a cyst will develop on one of the ovaries. Many women will develop at least one cyst during their lifetime. In most cases, cysts are painless and cause no symptoms.