<prompt> Ovulation is primarily caused by preovulatory surge ofEstradiolLuteinizing hormoneProgesteroneFollicle stimulating hormone  <response>: Estrogen levels peak towards the end of the follicular phase. This causes a surge in levels of luteinizing hormone LH and follicle-stimulating hormone FSH. This lasts from 24 to 36 hours, and results in the rupture of the ovarian follicles, causing the oocyte to be released from the ovary the oviduct.Ref: Ganong;s review of medical physiology; 24th edition; page no:-406 