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"Cytotrophoblast" is the name given to both the inner layer of the trophoblast (also called layer of Langhans) or the cells that live there. It is interior to the syncytiotrophoblast and external to the wall of the blastocyst in a developing embryo.
In the late blastocyst, the trophectoderm is known as the trophoblast. [2] The trophoblast gives rise to the chorion and amnion , the two fetal membranes that surround the embryo. The placenta derives from the embryonic chorion (the portion of the chorion that develops villi ) and the underlying uterine tissue of the mother.
On approximately the seventh day of development, the trophoblast (cells that make up the outer part of the blastocyst) divides to form two separate layers: an inner cytotrophoblast layer, and an outer syncytiotrophoblast layer. Using enzymes, the syncytiotrophoblast penetrates the tissues of the mother, then it attaches to these tissues by ...
The division of blastomeres from the zygote allows a single fertile cell to continue to cleave and differentiate until a blastocyst forms. The differentiation of the blastomere allows for the development of two distinct cell populations: the inner cell mass, which becomes the precursor to the embryo, and the trophectoderm, which becomes the precursor to the placenta.
The blastocoel further expands and the inner cell mass becomes positioned on one side of the trophoblast cells forming a mammalian blastula, called a blastocyst. The axis formed by the inner cell mass and the blastocoel is the first axis of symmetry of mammalian embryo and determines its attachment point to the uterus.
CPM occurs in one of two ways: Mitotic CPM - Mitotic non-disjunction can occur in a trophoblast cell or a non-fetal cell from the inner cell mass creating a trisomic cell line in the tissue which is destined to become the placental mesoderm. Meiotic CPM - Alternatively, CPM can occur through the mechanism of trisomic rescue. If a trisomic ...
Beginning on day eight, the amniotic sac is the first new cavity to form during the second week of development. [4] Fluid collects between the epiblast and the hypoblast, which splits the epiblast into two portions. The layer at the embryonic pole grows around the amniotic sac, creating a barrier from the cytotrophoblast.
Extravillous trophoblasts (EVTs), are one form of differentiated trophoblast cells of the placenta. They are invasive mesenchymal cells which function to establish critical tissue connection in the developing placental-uterine interface.