<unk>  (from the Greek 'syn'- "together"; 'cytio'- "of cells"; 'tropho'- "nutrition"; 'blast'- "bud") is the epithelial covering of the highly vascular embryonic placental villi, which invades the wall of the uterus to establish nutrient circulation between the embryo and the mother. It is a multi-nucleate, terminally differentiated syncytium, extending to 13cm.
Syncytiotrophoblast
Cytotrophoblast
Extravillous trophoblast
Hemangioblast
Athelia 
Trophoblast
Elliptocyte
Neurilemma