Histology of the Uterus

The uterus wall has three histological layers — the perimetrium, myometrium, and endometrium.

The outermost perimetrium is a thin serous membrane laterally continuous with the broad ligament, anchoring the uterus within the pelvic cavity.

The myometrium is the thickest middle layer, mainly composed of bundles of smooth muscle tissue.

Its contractions facilitate the expulsion of the uterine lining during menstruation or the fetus and the placenta during childbirth.

The endometrium is the innermost layer lining the uterine cavity, with simple columnar epithelial cells facing the lumen.

These cells are vascularized by straight and spiral arterioles in the underlying thick lamina propria region of areolar connective tissue.

The endometrium is subdivided into two distinct layers — the functional layer, or stratum functionalis, and the basal layer, or the stratum basalis.

The stratum functionalis changes in response to sex hormone levels. For instance, it thickens during the monthly menstrual cycle.

In contrast, the stratum basalis remains intact and regenerates the functional layer.