Mahatmasara Adhiwasa (0906550865)

Cytotrophoblast

The cytotrophoblast (or layer of Langhans) is the inner layer of the trophoblast, interior to the syncytiotrophoblast in an embryo. Trophoblasts have essential role in embryo implantation and interaction with the decidualised maternal uterus. The core of placental villi contain mesenchymal cells and placental blood vessels that are directly connected to the fetal circulation via the umbilical cord. This core is surrounded by two layers of trophoblast; a single layer of mononuclear cytotrophoblast that fuse together to form the overlying multinucleated syncytiotrophoblast layer that covers the entire surface of the placenta. The syncytiotrophoblast is in direct contact with the maternal blood that reaches the placental surface, and thus facilitates the exchange of nutrients, wastes and gases between the maternal and fetal systems

Cytotrophoblast in the tips of villi can differentiate into another type of trophoblast called the extravillous trophoblast. Extravillous trophoblast grow out from the placenta and penetrate into the decidualised uterus. This invasion of the maternal vessels by the cytotrophoblast leads to the destruction of the smooth muscle layer and to a partial replacement of the endothelial cells. It is responsible for the change in elasticity of the spiral arteries, whereby the blood circulation of this fetoplacental unit is adapted to the rapid growth of the fetus.

1.Syncytiotrophoblast (ST) 2.Cytotrophoblast (CT) 3.Endothelialcells 4.Smooth muscle cells

5.SpiralArteries 6.Endovascular cytotrophoblast

References:

1. Anonymous. Human Embryology Embriogenesis. Development of the Placental Vili. [Available Online] [cited from the URL http://www.embryology.ch/anglais/fplacenta/villosite03.html]

2. Anonymous. The development of Placenta. [Available Online] [cited from the URL https://courses.stu.qmul.ac.uk/smd/kb/microanatomy/humandev/placenta/index.htm]