PROGESTERONE-RECEPTOR IMMUNOREACTIVITY AT THE MATERNOFETAL INTERFACE OF FIRST TRIMESTER PREGNANCY - A STUDY OF THE TROPHOBLAST POPULATION

The aim of our study was to localize oestrogen receptor (ER) and proge sterone receptor (PR) in the trophoblast population at the maternofeta l interface in early pregnancy, Rat monoclonal antibodies to human ER and PR were used to study 44 cases of chorionic villi and 82 cases of decidua using an immunocytochemical method, The PR-immunoreactive prod ucts were localized in the nuclei of syncytiotrophoblast and cytotroph oblast cells of the villi, Specific staining was also present in the c ytoplasm, Villous stroma and vessels were stained occasionally, Using cytokeratin staining in an adjacent section or double staining with PR and cytokeratin, the distribution of invading trophoblast cells and t heir PR expression were examined, In decidual stroma, a type of inters titial cell was identified which simultaneously expressed cytokeratin and PR in the cytoplasm, indicating that the invading trophoblast cell s may express PR, All extravillous populations at the interface were p ositive for PR, including the syncytial lining of the decidual surface , the cytotrophoblast column, the cytotrophoblast shell and the inters titial trophoblast. The immunoreactivity of PR was also localized in t he nuclei of vascular endothelial cells, whereas Factor VIII was local ized in the cytoplasm of the same cells, thus confirming their endothe lial nature, In contrast to PR, little ER could be detected in the tro phoblast cell population using anti-ER antibody D75 in our study.