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A layer of ectodermal epithelium covering the outer surface of the chorion and chorionic villi of many mammals.



the exterior layer of cells in the embryos of mammals. The trophoblast is isolated in the blastocyst stage and makes possible contact between the embryo and the mother’s system by allowing nutrients to pass from the mother to the embryo. The part of the trophoblast located above the embryonic shield is called Rauber’s layer. The trophoblast that is lined internally with mesenchymal cells is called the chorion. The trophoblast plays a role in the implantation of the embryo in the uterine wall and the formation of the placenta.

References in periodicals archive ?
In placenta, the trophoblast cells are characterized by elevated expression of coagulation components, such as TF and TM, which are not only involved in hemostasis, but also in the differentiation of blood vessels of the placenta (21).
UMR-106, rat osteosarcoma cells and HTR8/SVneo, human trophoblast cells, were grown in Dulbecco modified Eagle medium (DMEM) supplemented with 10% FBS, 2 mM glutamine, 100 Units/ml penicillin and 100 [micro]g/ml streptomycin.
Stimulation of 2',5'-oligoadenylate synthetase activity in sheep endometrium during pregnancy, by intrauterine infusion of ovine trophoblast protein-1, and by intramuscular administration of recombinant bovine interferon-alpha I1.
Divergent trophoblast invasion and apoptosis in placental bed spiral arteries from pregnancies complicated by maternal anemia and early-onset preeclampsia/intrauterine growth restriction.
b) alterations in trophoblast turnover differ between PE and IUGR.
At least two mechanistic hypotheses have been used to explain higher embryonic mortality in IVP pregnancies: (a) failure in extraembryonic membrane formation and attachment: suboptimal IVP conditions impair development, leading to conceptus growth retardation, delayed attachment and placentation, further restricting growth, and leading to death for reduced transfer capacity between the embryo and the maternal system (28, 30, 32); and (b) expression of surface antigens from the MHC I complex in the trophoblast of SCNT-derived concepti, which may lead to rejection of the allograft (37).
Much of the increase in cellular mass of the embryo is attributed to growth of the trophectoderm, which is known as the trophoblast in later stages of embryogenesis.
The final part of the effort is to perform morphologic, endocrine, and molecular assessments of the villous placenta, trophoblast, conceptus membranes, and maternal decidua.
Natural killer cells keep a check on the trophoblast, the part of the embryo destined to become the unborn baby's placenta, which penetrates the wall of the womb after implantation.
It consists of two parts B: the outer layer of cells called the trophoblast and an inner cell mass consisting of about 30-150 cells.