Source:http://linkedlifedata.com/resource/umls/id/C0025344
MSH: The periodic shedding of the ENDOMETRIUM and associated menstrual bleeding in the MENSTRUAL CYCLE of humans and primates. Menstruation is due to the decline in circulating PROGESTERONE, and occurs at the late LUTEAL PHASE when LUTEOLYSIS of the CORPUS LUTEUM takes place.,NCI: Periodic discharge of blood and tissue from the uterus. From puberty until menopause, menstruation occurs about every 28 days when a woman is not pregnant.,GO: The cyclic, physiologic discharge through the vagina of blood and endometrial tissues from the nonpregnant uterus. [GOC:curators, PMID:8693059],MEDLINEPLUS: <p>Menstruation, or period, is a woman's monthly bleeding. Every month, your body prepares for pregnancy. If no pregnancy occurs, the uterus sheds its lining. The menstrual blood is partly blood and partly tissue from inside the uterus, or womb. It passes out of the body through the vagina. Periods usually start around age 12 and continue until <a href='http://www.nlm.nih.gov/medlineplus/menopause.html'>menopause</a>, at