The mesentery is part of the peritoneum. Polyps may also grow in the stomach, duodenum, spleen, kidneys, liver, mesentery and small bowel. Peritoneal folds develop from the ventral and dorsal mesentery of the embryo. The spleen develops from mesenchymal cells between layers of the dorsal mesentery of the stomach. Arteries, veins, lymph vessels and nerves travel within the mesentery. The primitive gut is suspended from the posterior abdominal wall by the dorsal mesentery. It is a remnant of the embryonic ventral mesentery. It is also found in the mesentery which is surrounding the intestine. Migration from the hindgut along the gut and across the dorsal mesentery then takes place. Dorsal mesentery, of the jejunal and ileal loops, forms the mesentery proper. Benign fatty tumors known as lipomas can form on the mesentery. The part of the dorsal mesentery that suspends the colon is termed the mesocolon. The root of the mesentery extends from the duodenojejunal flexure to the ileocaecal junction. Specifically, the spleen forms within, and from, the dorsal mesentery. During these topographic changes, the dorsal mesentery undergoes corresponding changes.