Trophoblast(redirected from chorionic ectoderm)
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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.