Ovum

The ovaries produce a female hormone, called estrogen, and store female sex cells (eggs or "ovum" - plural, ova) The female, unlike the male, does not manufacture the sex cells. A girl baby is born with about 60,000 of these cells, which are contained in sac-like depressions in the ovaries. Each of these cells may have the potential to mature for fertilization, but in actuality, only about 400 ripen during the woman's lifetime.