Chorion(绒毛膜) Formed by trophoblast +extraembryonic mesoderm chorion frondosum(丛密绒毛膜) embryonic pole Chorion laeve(平滑绒毛膜) abembryonic pole Decidua basalis Decidua Chorion parietalis frondosum connecting Chorion cavity. Decidua capsularIs UterineChorion（绒毛膜） •Formed by trophoblast +extraembryonic mesoderm •Chorion frondosum（丛密绒毛膜）- embryonic pole •Chorion laeve（平滑绒毛膜）- abembryonic pole