Changes in luteinizing hormone-releasing hormone in human placenta throughout pregnancy

The distribution and content of luteinizing hormone-releasing hormone (LH-RH) in human placental tissues were detected by enzymatic antibody and immunofluorescence techniques. Anti-LH-RH was taken up strongly by cytotrophoblasts and the villous stroma at 8 weeks of pregnancy; the uptake decreased with the progress of pregnancy. Anti-LH-RH was not taken up at all by syncytiotrophoblasts throughout pregnancy. These findings suggest that LH-RH is synthesized in the cytotrophoblast and villous stroma. The role of placental LH-RH in the synthesis of human chorionic gonadotropin is discussed.