Development of the digestive system posterior abdominal wall. By the fifth week, the connecting tissue bridge has narrowed, and the caudal part of the foregut, the midgut, and a major part of the hindgut are suspended from the abdominal wall by the dorsal mesentery, which extends from the lower end of the esophagus to the cloacal region of the hindgut. In the region of the stomach, it forms the dorsal mesogastrium or greater omentum. In the region of the duodenum, it forms the dorsal mesoduodenum; and in the region of the colon, it forms the dorsal mesocolon. Dorsal mesentery, of the jejunal and ileal loops,
Human digestive system the duodenum. (The enzymes that digest polysaccharides, by contrast, are primarily produced by the walls of the intestines.) The cells are filled with secretory granules containing the precursor digestive enzymes. The major proteases, the pancreatic enzymes which work on proteins, are trypsinogen and chymotrypsinogen. Elastase is also produced. Smaller amounts of lipase and amylase are secreted. The pancreas also secretes phospholipase A2, lysophospholipase, and cholesterol esterase. The precursor zymogens, are inactive variants of the enzymes; which avoids the onset of pancreatitis caused by autodegradation. Once released in the intestine, the enzyme enteropeptidase present in the intestinal mucosa activates trypsinogen by