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
Topical progesterone of tissue exposure to progesterone with this route of administration. These findings provide a possible explanation for how some studies found antiproliferative and atrophic changes in the endometrium with topical progesterone. However, elevated levels of progesterone in the endometrium with topical progesterone have not yet been demonstrated. Concern has been raised regarding topical progesterone in that the effects of such supraphysiological levels of progesterone in tissues are unknown and hence the potential for harmful effects has not been ruled out. Salivary monitoring of progesterone levels in women using topical progesterone and adjustment of dosage as necessary has been suggested as