Specialized zones in the trophoblast of the human term placenta.

摘要: Abstract The trophoblast of the free chorionic villi in human term placenta has been studied by a combined technique topography light microscopy and electron same regions. Two principal zones are recognized: alpha zones, which thinner, present characteristic ultrastructure cells specialized absorption or active transport substances. Mainly formed syncytium, they have microvilli, pinosomes, apical canaliculi, phagosomes, lysosomes, basal infoldings. beta thicker, with numerous nuclei presence both syncytium cytotrophoblast. These show great development organelles related to cellular synthesis, i.e., ergastoplasm, ribosomes, polysomes, mitochondria, Golgi, vesicles. Speculations offered as possible structural location synthesis gonadotropin, estrogens, progesterone. As working hypothesis, mechanism interrelationship is proposed between cyto- syncytiotrophoblast at term, explains apparent discrepancy low level gonadotropin high levels estrogen progesterone term.