[Immunohistochemical localization of human chorionic gonadotropin and human placental lactogen in placentas of various ages].

By means of the peroxidase-anti-peroxidase reaction it was possible to identify HCG and HPL in placentas between the 6th and 40th weeks in the syncytiotrophoblast, though not in the cytotrophoblast, the villous stroma or in vascular endothelia. A cytophotometric extinction measurement at 425 nm revealed a strong reaction intensity for HCG during the first trimester, a reduction to half this value in the second and further reduction in term placentas. In the 6th and 10th weeks of pregnancy only low quantities of HPL were demonstrable; the amount increased in the second trimester, attaining a maximum in the 24th week. In the third trimester the reaction intensity also decreased for HPL. Irrespective of the gestational age the identification decreased in the syncytiotrophoblast for both hormones in the following order; proliferation buds, necleated portions of epithelium, non-nucleated epithelial squamae, syncytiocapillary membranes, epithelium in cases with fibrosis of the villous stroma, epithelial nodes with nuclear pyknosis.