The mesothelium, Teflon or Velcro?

Sampson's transplantation theory for the pathogenesis of peritoneal endomet riosis is widely accepted. The events that take place, however, on the cell ular and subcellular level during the transition of endometrial tissue in t he abdominal cavity into peritoneal endometriosis remain controversial. The mesothelium plays a central role in the debate on this subject,The interac tion between endometrium and peritoneum has been studied in an in-vitro mod el using amnion, peritoneum and mesothelial cells in culture on the one han d and cyclic and menstrual endometrium on the other hand. The results of th ese studies indicate that (i) an intact mesothelial lining prevents adhesio n of shed endometrial tissue, (ii) shed endometrial tissue adheres to the p eritoneal extracellular matrix and (iii) menstrual effluent creates its own adhesion sites by damaging the mesothelial lining thus exposing the extrac ellular matrix. Therefore we conclude that the mesothelium has the properti es of Teflon, while the extracellular matrix resembles Velcro.