Many theories have been proposed to try and explain endometriosis. Most fail to explain every aspect of this highly variable condition.
In the 1920′s John Sampson of New York proposed that endometriosis resulted from retrograde menstruation. In other words some part of the menstrual loss flows up the Fallopian tubes and on to the surfaces of the pelvic organs rather than out of the body through the cervix. Since that time no-one has explained why this disturbance to the menstrual loss, occurs though many other theories have been advanced to try and explain the presence of the lining of the womb on the pelvic organs.
Spread through blood vessels and lymphatics was a possibility (The Lymphovascular theories). Simple (and magical) transformation of the peritoneal lining into endometrium was a possibiity (The Coelomic Metaplasia Theory). Finally, there have been many immunological and genetic theories though none suggest themselves as serious contenders. They are based on some weak associations between first degree relatives i.e. if your mother or sister has endometriosis then you are more likely to have it than someone else who is not a relative. These can easily be explained by diet or patterns of childbirth in your family.
The uterine denervation-reinnervation view does not explain every aspect of the condition though it uses general principles of tissue injury and repair to cover most clinical presentations. It explains the mechanism of retrograde menstruation, the attachment of endometriosis to injured peritoneal surfaces and the later development of gynaecological symptoms.