The layer of the mononucleated cytotrophoblast cells is the basal layer of villous trophoblast and located underneath the multinucleated syncytiotrophoblast (see Fig. 3.1c). These stem cells rest on a basement membrane, maintaining their proliferative activity throughout gestation. Hence, the total number of villous cytotrophoblast cells continuously increases during pregnancy, from about 1 x 109 at 13-16 weeks to about 6 x 109 at 37-41 weeks of gestation.
During gestation, cytotrophoblast cells are prevented from coming into direct contact with maternal blood. Damaged areas of syncytiotrophoblast are filled with fibrin-type fibrinoid (a blood clot product) to cover the exposed cytotrophoblast cells and to separate them and to keep them from coming into direct contact with maternal blood .
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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.