Menstrual Cycle

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Menstrual cycle: Lining of uterus thickens and egg is released
Menstrual cycle: Uterine lining is shed

During the follicular phase of the menstrual cycle, the lining of the uterus thickens. An egg becomes ready to be released inside a sac (follicle) on the surface of an ovary. During the luteal phase, the egg is released (ovulation). If the egg is fertilized by sperm, it may attach to the lining of the uterus (implant), and pregnancy begins. If the egg is not fertilized or a fertilized egg doesn't implant, the lining of the uterus is shed as blood during the menstrual period (below), and the cycle starts over.

Current as of: August 2, 2022

Author: Healthwise Staff
Medical Review:
Sarah Marshall MD - Family Medicine
Martin J. Gabica MD - Family Medicine
Kathleen Romito MD - Family Medicine
Rebecca Sue Uranga MD - Obstetrics and Gynecology
JoLynn Montgomery PA - Family Medicine




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