Pathogenesis of Endometriosis

Endometriosis was described as a disease process over 300 years ago. In the late 17th century it was recognized as peritoneal ‘ulcers’ occurring on the surface of the bladder, intestine, and surface of the uterus.1 In the 18th century physicians associated endometriosis with scarring, tissue damage, and pelvic pain. With improvements in microscopy, 19th century investigators identified the growth of ectopic endometrial tissue as the cause of these lesions. However, although it has been extensively investigated, the cause of growth of ectopic endometrial tissue (i.e. glands and stroma) outside the uterus has remained undefined.