 This layer elevates and closes dorsally, while the gut tube rolls up and closes ventrally to create a “tube on top of a tube.” The mesoderm, which is another layer of the trilaminar germ disc, holds the tubes together and the lateral plate mesoderm, the middle layer of the germ disc, splits to form a visceral layer associated with the gut and a parietal layer, which along with the overlying ectoderm, forms the lateral body wall.The space between the visceral and parietal layers of lateral plate mesoderm is the primitive body cavity.When the lateral body wall folds, it moves ventrally and fuses at the midline.