What does the endometrium look like?

Endometrium is a layer that constitutes the inner wall of mammalian uterus. It is normally divided into functional layer and basal layer. It has certain response to estrogen and progesterone. With the change of hormone level, periodic significant changes occur. The surface of the endometrium is the dense layer and the sponge layer, collectively referred to as the functional layer. With the changes of ovarian sex hormones, periodic changes occur, resulting in menstrual cramps. The basal layer refers to the 1/3 endometrium near the myometrium. This layer is not affected by sex hormones and will not undergo periodic changes. Under physiological conditions, the thickness of the endometrium fluctuates between 5-10 mm. Normally, before menstrual cramps, the endometrium is the thickest, close to 10 mm. At the end of menstruation, the endometrium should be 5mm thick, and the ovulation period is about 7-8 mm. If the endometrium is too thin, it is easy to cause the fertilized egg implantation failure.