The Normal Histology of the Endometrium

Abstract

The endometrium of the corpus is composed of two layers: the basalis (the layer from which the endometrium regenerates after menstrual shedding) and the overlying functionalis. In the second half of the menstrual cycle, the functionalis may be differentiated into the superficial compacta and the underlying spongiosa, which extends to the basalis. During the menstrual cycle the endometrium varies from 1 mm (postmenstrual) to about 8 mm at the end of the 3rd week. Every layer consists of two major structures: the epithelial component, either as glands or as superficial epithelium, and the mesenchymal component of stromal cells. Both cellular components are pluripotential and can undergo various metaplastic changes.