Ovulation
![](/Images/godic/202502/04/Figure_28_00_013637.JPG")
![Ovulation occurs about midway through the menstrual cycle, after the follicular phase, and is followed by the luteal phase. Note that ovulation is characterized by a sharp spike in levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH), resulting from the peak of estrogen levels during the follicular phase.](/Images/godic/202502/04/MenstrualCycle2_en.svg3638.png")
![This diagram shows the hormonal changes around the time of ovulation, as well as the inter-cycle and inter-female variabilities in its timing.](/Images/godic/202502/04/Hormones_estradiol,_progesterone,_LH_and_FSH_during_menstrual_cycle3638.png")
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.