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Menstrual Cycle

Picture of menstrual cycle: Lining of uterus thickens and egg is released

During the follicular phase of the menstrual cycle, the lining of the uterus thickens to prepare for pregnancy. 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 (implant in) the lining of the uterus, and pregnancy begins. If the egg is not fertilized or does not implant, the lining of the uterus is shed as blood during the menstrual period (below), and the cycle starts over.

Picture of menstrual cycle: Uterine lining is shed
By Healthwise Staff
Primary Medical Reviewer Sarah Marshall, MD - Family Medicine
Specialist Medical Reviewer Kirtly Jones, MD - Obstetrics and Gynecology
Last Revised November 10, 2010

Last Revised: November 10, 2010

Author: Healthwise Staff

Medical Review: Sarah Marshall, MD - Family Medicine & Kirtly Jones, MD - Obstetrics and Gynecology

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