Lateral Plates
Lateral Plates
paired structures originating in the course of embryonic development in all chordates during the separation of the middle germ layer. The lateral plates consist of two sheets: outer (parietal), adjacent to the body wall, and inner (visceral), adjacent to the intestinal wall. A secondary body cavity or coelom develops between them. The serous membranes, smooth muscles, mesenchyma, blood vessels, heart, and mesentery are derived from the lateral plates during embryonic development.