Benign Diseases of the Endometrium

Abstract

The endometrium and the myometrium are of mesodermal origin and are formed secondary to fusion of the müllerian (paramesonephric) ducts between the 8th and 9th postovulatory weeks. The cervix is generally considered to be of müllerian origin, although it has been claimed that its mucous membrane is derived from the urogenital sinus; however, the exact contribution of müllerian and sinus tissue to the cervix remains uncertain [47]. Until the 20th week of gestation, the endometrium consists of a single layer of columnar epithelium supported by a thick layer of fibroblastic stroma. After the 20th gestational week, the surface epithelium invaginates into the underlying stroma, forming glandular structures that extend toward the underlying myometrium. At birth, the uterus, which is made up of the uterine corpus and uterine cervix, measures approximately 4 cm in length, the majority of which is made up of the cervix. The endometrium measures less than 0.5 mm in thickness, and the surface and glands are lined by a low columnar to cuboidal epithelium devoid of either proliferative or secretory activity, which resembles the inactive endometrium of postmenopausal women.