<Tr> <Th> FMA </Th> <Td> 17742 </Td> </Tr> <Tr> <Td_colspan="2"> Anatomical terminology (edit on Wikidata) </Td> </Tr> <P> The endometrium is the inner epithelial layer, along with its mucous membrane, of the mammalian uterus . It has a basal layer and a functional layer; the functional layer thickens and then is sloughed during the menstrual cycle or estrous cycle . During pregnancy, the glands and blood vessels in the endometrium further increase in size and number . Vascular spaces fuse and become interconnected, forming the placenta, which supplies oxygen and nutrition to the embryo and fetus . The presence of commensal bacteria in the uterus and endometrium has been identified . </P> <P> The endometrium consists of a single layer of columnar epithelium plus the stroma on which it rests . The stroma is a layer of connective tissue that varies in thickness according to hormonal influences . Simple tubular uterine glands reach from the endometrial surface through to the base of the stroma, which also carries a rich blood supply of spiral arteries . In a woman of reproductive age, two layers of endometrium can be distinguished . These two layers occur only in endometrium lining the cavity of the uterus, not in the lining of the uterine (Fallopian) tubes: </P>

The functional layer of the endometrium is shed in response to