[Immunoelectron microscopic localization of human chorionic gonadotropin in the syncytiotrophoblast of hydatidiform moles].

The immunocytochemical localization of hCG in the syncytiotrophoblast of hydatidiform moles was observed by means of the immunoglobulin gold technique with rabbit anti-human hCG serum. Immunoreactive gold particles of hCG are preferentially localized in the distal portion of the Golgi complexes, Golgi-derived secretory granules 200-300 nm in diameter, and large electron dense bodies 500-1,000 nm in diameter. The secretory granules exist throughout the cytoplasm above the nuclear region and are occasionally released by exocytosis from the syncytiotrophoblast. On the other hand, the large electron dense granules seem to be cytolysosomes in nature and are involved in uptake and storage of hCG.