, Michel Canis 2

BACKGROUND: Recent studies have indicated new physiological roles for erythropoietin (Epo) unrelated to erythropoiesis. We previously demonstrated that the Epo concentrations in peritoneal ¯uid from patients with stage I endometriosis were signi®cantly higher than those with stages II, III and IV of the disease. Therefore, we hypothesized that Epo may play a role in the pathogenesis of endometriosis, particularly during the early stages of the disease. METHOD: We investigated the localization of Epo and the Epo receptor (Epo-R) in peritoneal endometriosis and eutopic endometrium, using immunohistochemistry. RESULTS: We detected Epo and Epo-R localized within glandular epithelial cells in both peritoneal endometriosis and eutopic endometrium. There was no signi®cant difference in Epo expression between red and black peritoneal lesions, whereas Epo-R expression was signi®cantly lower in black peritoneal lesions when compared to red lesions. Epo and Epo-R expression levels within red peritoneal lesions were comparable to those of eutopic endometrium from patients with endometriosis. CONCLUSION: The present ®ndings suggest that Epo may play a role in the pathophysiology of endometriosis. Key words: black endometriotic lesions/erythropoietin/erythropoietin-receptor/red endometriotic lesions