Human intermediate trophoblasts express chorionic gonadotropin/luteinizing hormone receptor gene.

Human cyto- and synchtiotrophoblasts have recently been shown to contain functional hCG/LH receptors. The present study investigated whether human intermediate trophoblasts also contain these receptors. Six implantation sites from 4-8 wk of pregnancy were processed for in situ hybridization for hCG/LH receptors coupled with immunocytochemistry for human placental lactogen (hPL), an endocrine marker for intermediate trophoblasts. In addition, the sections were also double-immunostained for hCG/LH receptor and hPL proteins. The results showed that some but not all the intermediate trophoblasts contained hCG/LH receptors. The intermediate trophoblasts in endovascular locations contained more receptors than those in perivascular locations. Villus syncytiotrophoblasts contained the highest level of receptors, followed by intermediate trophoblasts in endovascular and perivascular locations and then villus cytotrophoblasts. These data, demonstrating the presence of hCG/LH receptors in intermediate trophoblasts, suggest a possible role for hCG in trophoblast invasion and maternal recognition of pregnancy.