<unk> " 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. The<unk>  is considered to be the trophoblastic stem cell because the layer surrounding the blastocyst remains while daughter cells differentiate and proliferate to function in multiple roles. There are two lineages that<unk> ic cells may differentiate through: fusion and invasive. The fusion lineage yields syncytiotrophoblast and the invasive lineage yields interstitial<unk>  cells.<unk> ic cells play an important role in the implantation of an embryo in the uterus.
Cytotrophoblast
Syncytiotrophoblast
Extravillous trophoblast
Athelia 
Trophoblast
Hemangioblast
Nurse cell
Neuroblast