Trophoblast

The trophoblast is a layer of flat to cubical cells forming the outer layer of the blastocyst epithelium (outer cell mass), which differentiates into the amniotic sac and the placenta (extraembryonic tissue of the embryo). It mediates the nidation of the egg (using trophoblast L-selectin binding to endometrial carbohydrate receptors, trophoblast integrins, laminin and endometrial intercellular mass fibronectin), then proliferates and differentiates into two layers:


 * inner layer: cytotrophoblast;
 * outer layer: syncytiotrophoblast.

Related articles

 * First week of embryonal development
 * Portal Embryology
 * Prenatal period
 * Amniotic sac and placenta
 * Placenta