<unk>  or, abbreviated,<unk> , are one form of differentiated<unk>  cells of the placenta. They are invasive mesenchymal cells which function to establish critical tissue connection in the developing placental-uterine interface.<unk> s derive from progenitor cytotrophoblasts (CYT), as does the other main<unk>  subtype, syncytiotrophoblast (SYN).<unk> s that derive from CYT cells on the surface of placental villi that come into contact with the uterine wall - at the placental bed - begin to express the HLA-G antigen. These interstitial subtype of<unk> s then have the ability to invade and implant into the maternal decidua, where they anchor the developing placenta. The endovascular<unk> s remodel maternal spiral arteries to control blood perfusion and oxygenation in the developing placenta.<unk>  are a low-incidence (<5% of<unk> s), but critical and multifunctional, subtype of<unk>  in the placenta.
Extravillous trophoblast
Cytotrophoblast
Syncytiotrophoblast
Athelia 
Hemangioblast
Neointima
Placental cotyledon
Stratified squamous epithelium