Localization of luteinizing hormone-releasing factor in the human placenta.

Luteinizing hormone-releasing factor (LRF) has been found to be produced by the placenta. In the present study, the localization of this releasing factor was delineated by the use of an immunofluorescnece technique. Intense fluorescence was localized in the cytotrophoblast, along the outer surface layer of the syncytiotrophoblast, and in the villous stroma. The cytoplasm of the syncytiotrophoblast did not exhibit any fluorescence. It may be speculated that placental LRF plays a role in regulating the production of human chorionic gonadotropin.