Pathogenesis of Endometriosis

Endometriosis is a condition characterized by the presence of endometrial tissue in ectopic foci outside the uterus. Despite being one of the most frequently encountered gynecologic diseases, the exact cause and pathogenesis of endometriosis is unclear. The pathogenesis of endometriosis has long been debated, but essentially theories can be divided into those that suggest (1) development in situ by metaplasia or (2) development as a consequence of the dissemination of endometrium (Table 1) . Research to date strongly suggests that the origin of epithelium is endometrium rather than the peritoneal mesothelium. This article critically examines the factors that may play a role in the cause and pathogenesis of endometriosis, with special emphasis on the potential immune mechanisms that may be involved.