IMMUNOHISTOCHEMICAL LOCALIZATION OF ENDOTHELIN-1 IN PLACENTA AND FETAL MEMBRANES IN TERM AND PRETERM HUMAN-PREGNANCY

PROBLEM: The aim of the study was to determine the ET-1 localization o n human placenta and fetal membranes and to compare its distribution b etween term and preterm pregnancies in laboring and non-laboring tissu es. METHODS: Tissues obtained from nine term elective resarean section , eight spontaneous vaginal term delivery, and 13 preterm delivery fro m both cesarean section (N = 6) and vaginal delivery (N = 7) were stud ied by immunohistochemistry.RESULTS: Immunoreactive ET-1 (IR-ET-1) was detected in villous and nonvillous trophoblast in all groups, althoug h laboring tissues showed strong staining in the syncytiotrophoblast o f the villi. ET-1 immunostaining of endothelial cells was observed in all placental villous vessels with a considerable variability within g roups. In the fetal membranes, intensive immunopositive staining was o bserved in the chorionic trophoblast following vaginal deliveries in t erm and preterm tissues. CONCLUSIONS: This is the first study to repor t the localization of IR-ET-1 in human fetal membranes and placenta, a nd suggests that amnion and trophoblast represents a source of ET-1 pr oduction or, alternatively, a site for ET-1 binding.