Increased expression of endoglin in the eutopic endometrium of women with endometriosis.

OBJECTIVE: To compare the angiogenic activities of endothelial cells in the eutopic endometrium of women with and without endometriosis. DESIGN: Vessels with active angiogenesis were identified using the monoclonal antibody to endoglin. SETTING: University department of obstetrics and gynecology. PATIENT(S): Twenty women with histologically confirmed endometriosis after laparotomy or laparoscopy. Women with carcinoma in situ of uterine cervix, but no evidence of endometriosis (n = 20), served as control subjects. INTERVENTION(S): Formalin-fixed, paraffin-embedded archival tissues were sectioned and stained. MAIN OUTCOME MEASURE(S): Number of vessels stained with monoclonal antibody to endoglin. RESULT(S): For all menstrual phases, the mean number of vessels with endoglin expression was significantly greater in patients with endometriosis compared with control subjects. In each menstrual phase, a significant difference was observed only during the late secretory phase. Within the group with endometriosis, the mean numbers of vessels with endoglin expression in stages I and II were not different from the numbers in stages III and IV. CONCLUSION(S): This study shows the expression of endoglin in the eutopic endometrium of women with endometriosis is significantly increased and the increase is observed only in the late secretory phase. It is suggested from these findings that activation of angiogenesis in the eutopic endometrium might be a key factor in the pathogenesis of endometriosis.