The syncytiotrophoblast is a multinucleated layer without lateral cell borders, hence there is a single syncytiotro-phoblast covering all villi of a single placenta. Microvilli on its apical surface provide amplification of the surface (sevenfold) and are in direct contact to the maternal blood floating within the intervillous space (see Fig. 3.1c). Growth and maintenance of the syncytiotrophoblast is completely dependent on the fusion with the underlying cytotrophoblast, since syncytial nuclei do not display transcriptional activity.
Within the syncytiotrophoblast the incorporated nuclei first exhibit a large and ovoid shape, while during maturation they become smaller and denser. Finally, they display envelope convolution, increased packing density and increased heterochromatinization [19,20].
Syncytial fusion by far exceeds the needs for growth since the syncytiotrophoblast needs steady input for the maintenance of its functional and structural integrity. Consequently, the nuclei that are incorporated into the syncytium are accumulated and packed into protrusions of the apical membrane. These syncytial knots are then extruded into the maternal circulation .
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Once your pregnancy is over and done with, your baby is happily in your arms, and youre headed back home from the hospital, youll begin to realize that things have only just begun. Over the next few days, weeks, and months, youre going to increasingly notice that your entire life has changed in more ways than you could ever imagine.