CURRENT CONCEPTS OF THE MECHANISMS OF MENSTRUATION - A NORMAL PROCESSOF TISSUE DESTRUCTION

Current data support the contention that menstruation is the consequen ce of the actions of matrix metalloproteinases (MMPs) in the endometri um, and that these enzymes are stimulated by the products of an inflam matory process. A number of MMPs, capable of degrading both interstiti al matrix and basement membrane components, have been localized to per imenstrual endometrium, and the focal nature of their production sugge sts local regulation. Emphasis is placed on important relationships be tween cells of the immune system (specifically, mast cells, eosinophil s, neutrophils and macrophages), and the local production and activati on of MMPs, whose degradative actions lead to loss of integrity of blo od vessels, destruction of endometrial interstitial matrix and the res ultant bleeding characteristic of menstruation.