Immunocytochemistry of the estrogen receptor in spontaneous endometriosis in rhesus macaques

Immunocytochemical, biochemical, and histologic analysis of endometriotic lesions and endometria from rhesus macaques with endometriosis revealed several distinctions between ectopic and eutopic endometrium. In lesions, unlike endometrium, neither the mean percentages of estrogen receptor positive (ER+) cells nor the total ER content changed significantly during the menstrual cycle. In eutopic endometria, ER staining in both stromal and epithelial cells increased and decreased synchronously during the cycle, but in endometriotic lesions, such synchrony was lacking. Moreover, in lesions, unlike endometria, the percentage of ER+ cells was low in the stroma and highly variable in epithelium throughout the cycle. These data, taken together, indicate a defect in the hormonal regulation of ER in endometriotic lesions of monkeys.