Endometriosis

Endometriosis is a non-malignant, estrogen-dependent disease of females associated with pelvic pain and infertility, in which tissue similar to the inner lining of the uterus (endometrium) is found in unexpected locations, particularly on the pelvic peritoneum and the ovaries. The disease is thought to be caused by retrograde menstruation and transplantation of endometrial tissue into these ectopic sites, where it generates adhesions, neo-angiogenesis, chronic inflammatory response,  growth, and invasion into nearby surfaces. About 6–10% of women of reproductive age have some form of endometriosis, with rates possibly higher in some populations. Little else is known about the cause, and diagnosis is difficult. Endometriosis occures in some monkeys, but seems to be rare in great apes.