Short-term culture of peritoneum explants confirms attachment of endometrium to intact peritoneal mesothelium

Objective: To evaluate the initial adhesion of endometrium to the peritoneu m. Design: Descriptive study using light and confocal laser-scanning microscop y, immunohistochemistry, and transmission electron microscopy. Setting: Uni versity-based laboratory. Patient(s): Women without endometriosis undergoing surgery for benign condi tions. Intervention(s): None. Main Outcome Measure(s): Explants of peritoneum (n = 20), prepared from fou r patients, were cultured for I hour with mechanically dispersed proliferat ive or secretory endometrium. Peritoneum was cultured with endometrium from the same patient. Specimens were fixed and serially sectioned for hematoxy lin and eosin stain, immunohistochemistry using an anti-cytokeratin monoclo nal antibody, and transmission electron microscopy. Result(s): In 17 of 20 explants, endometrium was adherent to intact mesothe lium. There was no evidence of transmesothelial invasion at any sites of at tachment. Although in most cases endometrium was adherent to mesothelium vi a endometrial stroma, there were many sites of endometrial epithelium-mesot helium attachment. Confocal laser scanning microscopy demonstrated an intac t monolayer of cytokeratin-positive cells below the sites of endometrial im plantation. Transmission electron microscopy demonstrated intact, viable, m esothelial cells below sites of attachment. Conclusion(s): This study demonstrates that endometrium rapidly adheres to intact peritoneal mesothelium. In addition, this study demonstrates that en dometrial epithelial cells. as well as stroma, can attach to mesothelium. F urther studies are needed that characterize the mechanism of endometrial-me sothelial cell adhesion. (C)2001 by American Society for Reproductive Medic ine.