A cyst is a fluid-filled mass. The ovary is a small organ of the female reproductive system, and its function is to create the egg during each cycle, as well as producing sperm (estrogen, progesterone). In very rare cases, these cysts can develop into cancer. There are two types of ovarian cyst: functional cysts, which can affect women of childbearing age, and organic cysts. The cause: hormonal disturbances in the woman, which may be due to the use of ovulation stimulants. Organic cysts cannot be digested and require surgical intervention.