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 disorder Menstrual disorder A menstrual disorder is an abnormal condition in a woman's menstrual cycle. Disorders of ovulation include oligoovulation and anovulation: "Polymenorrhea" is the medical term for cycles with intervals of 21 days or fewer. "Irregular menstruation" is where there is variation in menstrual cycle length of more than approximately eight days for a woman. The term "metrorrhagia" is often used for irregular menstruation that occurs between the expected menstrual periods. "Oligomenorrhea" is the medical term for infrequent, often light menstrual periods (intervals exceeding 35 days). "Amenorrhea" is the absence of a menstrual period in a woman of reproductive age.