pubmed:abstractText |
In human pregnancies, trophoblasts, in contrast to placental connective tissue and the fetus itself, come into direct contact with the maternal allorecognizing system at special sites. Villous syncytiotrophoblasts washed around by maternal blood lack HLA class I proteins, whereas extravillous trophoblasts, which deeply invade maternal uterine tissues, express high amounts of HLA-G and also HLA-C, the latter to a lesser degree, however. A subpopulation of extravillous trophoblasts, the endovascular trophoblast, enters maternal spiral artery lumen and, like syncytiotrophoblast, comes into direct contact with maternal blood. Less is known about HLA class I distribution on this endovascular trophoblast subpopulation.
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