The mesentery is a fold of membranous tissue that arises from the posterior wall of the peritoneal cavity and attaches to the intestinal tract.Within it are the arteries and veins that supply the intestine.he embryologic forerunner of the gastrointestinal tract is suspended from the posterior abdominal wall by the dorsal mesentery. The gastrointestinal tract and associated dorsal mesentery are subdivided into foregut, midgut and hindgut regions based on the respective blood supply.