Endometrium on the opposite side to the decidua basalis is the decidua parietalis.

The remainder of the decidua is termed the decidua parietalis or decidua vera.

As the chorion grows, the chorion laeve comes in contact with the decidua parietalis and these layers fuse.

Decidua parietalis - All other decidua on the uterine surface belongs to decidua parietalis.

The remainder of the decidua is termed the decidua parietalis or decidua vera.