Caption

Endometriosis. Computer artwork of endrometriomas, masses of cells from the lining of the uterus, thickening (right) and bleeding (bottom). Endometriosis is the movement of cells from the lining of the uterus to the abdominal cavity. The cells still respond to the menstrual cycle and so bleed once a month. However, the blood has no way of leaving the body and so causes pain, inflammation and scar tissue, and can lead to infertility.