Ovaries store between 200,000 and 400,000 follicles, tiny sacs, present from birth, that nurture immature eggs, or ova. The egg travels down the fallopian tube into the uterus, where it either is fertilized by a man's sperm or, if unfertilized, breaks down and is excreted as part of the menstrual cycle.
Ovaries also secrete the important reproductive hormones estrogen and progesterone.
Ovarian Cancers Ovarian cancers are potentially life-threatening malignancies, that develop in one or both ovaries. Germ cell tumors. These cancers develop in a layer of cube-shaped cells known as the germinal epithelium , which surrounds the outside of the ovaries. Germ Cell Tumors. They occur most often in teenagers and young women.