Menstruation and endometrial repair

Menstruation is the process by which the functionalis layer of the endometrium is shed and restored during each menstrual cycle in women, without scarring or loss of function. The trigger for menstruation is withdrawal of hormonal support in a nonconception cycle, which induces highly controlled inflammatory mechanisms starting with influx and activation of specific leukocyte subsets and release of bioactive mediators, including degradative enzymes. Tissue breakdown and repair occur simultaneously in different/adjacent areas of the tissue. Re-epithelialization rapidly covers the degraded surface, independently of hormone (estrogen) support: full regeneration of the endometrial functionalis follows with estrogen support during the ensuing proliferative phase