Ovulation is the release of egg from the ovaries. In humans, this event occurs when the
de Graaf's follicles rupture and release the secondary oocyte
ovarian cells. After ovulation, during the
luteal phase, the egg will be available to be
fertilized by
sperm. In addition, the
uterine lining (
endometrium) is thickened to be able to receive a fertilized egg. If no conception occurs, the uterine lining as well as blood will be shed during
menstruation.