Gynaecology & Obstetrics In physiology of the menstrual cycle, all are true EXCEPT ? A Ovulation follows 36 hours after the onset of LH surge B Follicular phase is constant C Withdrawal of endogenous progesterone results in endometrial breakdown and subsequent menstruation D Average cycle length is 21-35 days 💡 Explanation In physiology of the menstrual cycle, all are true EXCEPT ? ✓ Correct Answer: B. Follicular phase is constant