Fetal blood is separated from syncytiotrophoblast with all the following except :

The decidua over the anembryonic pole is the decidua capsularis.As the chorionic cavity becomes larger, the decidua capsularis is streched and degenerates .The chorion leave now comes into close contact with the uterine wall on the opposite side,resulting in the formation of the decidua parietalis. For more information refer page no 59,60 and also fig.5,18 ,of textbook of obsteics,sheila balakrishnan,2 nd edition. layers of placental barrier from maternal to fetal side includes: maternal blood<syncytiotrophoblast<cytotrophoblast<connective tisssue stroma of villus<fetal blood vessel Reference: D C Dutta Text book of Obstetrics 7th edition page 34