IMMUNOLOCALIZATION OF THE VASOCONSTRICTOR ENDOTHELIN IN HUMAN ENDOMETRIUM DURING THE MENSTRUAL-CYCLE AND IN UMBILICAL-CORD AT BIRTH

OBJECTIVE: Our objective was to determine the localization of immunoreactive endothelin in human cyclic endometrium and in umbilical cord during normal delivery and after cesarean section. STUDY DESIGN: Fixed dated endometrial tissue (n = 41) and umbilical cord (n = 6) were subjected to immunohistochemistry with an antiserum cross reacting with endothelin-1, -2 and -3. RESULTS: Low levels of stromal endometrial staining were seen throughout the cycle. The strongest staining was in luminal epithelium throughout the secretory phase and in glandular epithelium in the late-secretory phase. In umbilical cord the most intense immunoreactivity was present on the amnion cells on the outer cord, with some staining in intermittent cells in the Wharton's jelly and in umbilical vein cells. No differences were detected between cord from normal delivery or cesarean section. CONCLUSION: A paracrine role is suggested for endothelin in regulation of endometrial function and a role in vasoconstriction in the umbilical cord at birth.