An egg being released from a mature follicle on the surface of the ovary.

Ovulation

Each month, a mature egg is released from one of the women's two ovaries -- this is called ovulation. Ovulation takes place about two weeks after the first day of the last menstrual period. The rare picture shown here is the clearest ever taken of human ovulation. Observing ovulation in humans is extremely rare, and previous images have been fuzzy.