The endometrium is the lining of the uterus. This tissue covers the inner wall of the uterus. At the beginning of each menstrual cycle, it thickens and becomes richly vascularized so that it can eventually accommodate an embryo during implantation. It is then sometimes called uterine lace.

Angiogenesis is essential for many physiological processes, including organ development, tissue repair and the female reproductive system. Human endometrial microvascular endothelial cells (HEMEC) are located in the inner lining of the uterus, called the endometrium. HEMECs are involved in endometrial angiogenesis during the menstrual cycle, with the rapid growth and fall of the endometrium. Angiogenesis in the endometrium occurs through the mechanisms of intussusception and vessel elongation. Studies have indicated that high proliferation of HEMEC in the endometrium can lead to disorders such as endometriosis and menorrhagia. Cultured HEMECs provide a useful model for elucidating the mechanisms of normal and pathological angiogenesis and developing treatments for disorders of the female reproductive system.