Endometrium the body with human chorionic gonadotropin (HCG). HCG provides continued feedback throughout pregnancy by maintaining the corpus luteum, which will continue its role of releasing progesterone and estrogen. The endometrial lining is either reabsorbed (estrous cycle) or shed (menstrual cycle). In the latter case, the process of shedding involves the breaking down of the lining, the tearing of small connective blood vessels, and the loss of the tissue and blood that had constituted it through the vagina. The entire process occurs over a period of several days. Menstruation may be accompanied by a series of uterine contractions; these help expel
Menstrual synchrony of northwestern California, according to one ethnographic study, "all of a household's fertile women who were not pregnant menstruated at the same time..." The phenomenon of menstrual synchrony is the closeness in time of the menstrual cycle onsets of two or more women. The phenomenon is not synchronization in the strict sense of concordance of menstrual cycle onsets but the term "menstrual synchrony" is still used perhaps misleadingly. As an undergraduate, Martha McClintock published the first study on menstrual synchrony; her report detailed the menstrual synchrony of undergraduate women living in a dormitory in Wellesley College. Since then, there have