The endometrium is the inner lining of the uterine wall.
The inner lining of the uterine wall is called the endometrium. The uterus is a hollow muscular secondary sex organ of the female reproductive system. After fertilization, the egg implant itself in the endometrial lining of the uterus. The egg gets nourishment from the uterus and develops into a fetus.
The uterine wall consists of three layers: the innermost layer (endometrium), the middle layer (myometrium), and the outermost layer (perimetrium). The endometrium is lined with simple columnar epithelial cells and forms the uterine mucosa membrane of the uterus. The epithelial layer consists of two types of cells (i) ciliated columnar cells and (ii) secretory columnar cells. The epithelial layer is followed by the lamina propria which consists of the connective tissue layer.
Based on the function, the endometrium is divided into two layers (i) the basal layer called the stratum basale and (ii) the functional layer called the stratum functionale. The basal layer attaches to the smooth muscle layer (the myometrium) and stays unchanged. The basal layer provides an anchor to the endometrium. The functional layer is changed in response to the hormonal changes during the menstrual cycle. In this layer of the endometrium, the fertilized egg implant and develops into a fetus.