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
Navicular cell Navicular cell Navicular cell is a boat-shaped benign epithelial cell seen in Pap smear. They are seen in pregnancy (most prominently during smears taken in the second trimester), second half of menstrual cycle, during menopause and in women using medroxyprogesterone acetate (depo-provera) for contraception. Navicular cells have folded edges, with a thickened outer rim of cytoplasm and an eccentric nucleus. They contain abundant glycogen in the cytoplasm, giving it a central yellow halo. The cytoplasm appears golden, refractile and granular under the microscope. In depo-provera users, the high progesterone levels result in more exfoliation of superficial squamous cells, thereby causing