An egg the overy continues to mature. Just before the mid-cycle the mature egg moves to the surface of the overy. The lining of the uterus called endometrium becomes thicker in preparation for implantation of the fertilize egg 3. This occurs when fertilization does not take place. The utering lining begins to break down and bleeding results, a process called menstruation, which lasts for 3 to 7 days. 1. The matured egg is released. It travels to the Fallopian tube and moves toward the utums.​