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KMID : 0376219820190020185
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Chonnam Medical Journal
1982 Volume.19 No. 2 p.185 ~ p.203
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The Fine Structure of the Trophoblast of Human Chorionic Villus
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Abstract
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Electron microscopic studies were made on the trophoblast of chorionic villi of human placenta from 6 gestational week to full-term and attempts were made to correlate the fine structure of trophoblasts with its possible functions.
The syncytiotrophoblasts and cytotrophoblasts differed widely in their fine structures: syncytiotrophoblast has well-developed cytoplasmic organelles and more cytoplasmic electron-density than cytotrophoblast and always bordered the intervillous space.
The microvilli, caveolae, endoplasmic reticulum, mitochondria and lipid droplets of the trophoblasts in the early periods differed considerably from those of the later periods.
At full-term, several cilia-like structures (250~320nm in diameter) were observed in some of the syncytiotrophoblast.
In the syncytiotrophoblast cytoplasm of the earlier periods, the cell membrane, desmosomes and vesicles existed before cell fusion were noted as the remnants, and cytoplasmic organelles such as endoplasmic reticulum were grouped together. And the cell membrane between syncytio and cytotrophoblast were often partially lost. These findings suggest that cytotrophoblast differentated into syncytiotrophoblast.
Between two neighboring trophoblasts, there were relatively uniform intercellular spaces, about 20~40nm wide, which were modified by desmosomes and rarely by tight junctions, and further, by expansions of intercellular spaces in which microvilli were noted.
Subtrophoblastic basal lamina increased in thickness from 85´120nm in earlier periods to 115-215nm in later periods. Some area of basal cell membrane of the trophoblast showed basal in folding or microvillous projections.
Regional aggregations of many syncytial nuclei(syncytial knots) bulged slightly into the intervillous space at full term.
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