Histochemistry of some enzymes in human embryonic and fetal placentae

Activities of the following enzymes were assessed in cryostat sections of human embryonic and fetal placentae aged 7 to 22 weeks of the intrauterine life using the standard methods recommended by Lojda et al. (1978): alkaline phosphatase (AIP), and acid phosphatase (AcP), non-specific esterase (ANE), ATP-cleaving enzymes (ATP-ase), beta-glucuronidase, thiamine pyrophosphatase, dipeptidylaminopeptidase IV (DPP IV), aminopeptidase A and M (APA, APM), gamma-glutamyltransferase (GGT), glycero-3-phosphate dehydrogenase and succinate dehydrogenase (alpha-GPDH, SDH). Since week 7 high activity of AIP has been proved in the apical zone of the plasmodiotrophoblast. At the same time the DPP IV activity appeared in the plasmodiotrophoblast, in the stroma of villi, and, latter on, in vascular endothelium. In the fetal placenta the APA activity was pronounced both in the cytotrophoblast and the stroma of villi. The activities of AcP and ANE were relatively weak. In the course of development the activities of most enzymes were gradually increasing.