What Is The Outermost Layer Of The Fetal Membrane?

What Is The Outermost Layer Of The Fetal Membrane? The chorion is a membrane comprised of four layers, particularly the cellular layer, the reticular layer, the basement membrane, and the trophoblast layer. The trophoblast is the outermost layer. The chorion and the amnion form the amniotic sac. What are the two layers of fetal membranes?