These receptors are commonly found on tumors located in the foregut, midgut, and hindgut. Interspersed in the midgut epithelium are nests of stem cells. The contents of the abdomen can be divided into the foregut, midgut, and hindgut. It can be divided into the foregut, midgut and hindgut. It traverses the peritrophic membrane of the mosquito midgut and crosses the midgut epithelium. The areas supplied by these arteries are used to define the midgut, hindgut and foregut. The areas supplied by these arteries are used to define the foregut, midgut, and hindgut. Carcinoid tumors of the midgut (jejunum, ileum, appendix, and cecum) are associated with carcinoid syndrome. The digestive system is typical of insects, with Malpighian tubules discharging into the midgut. After blood meal ingestion, proteases are active only in the posterior midgut. The small intestine develops from the midgut of the primitive gut tube. The junction between the embryological foregut and midgut lies just below the major duodenal papilla. All posterior midgut activity is restricted to the posterior midgut lumen. The microfilariae retain the sheath until they are digested in the mosquito midgut. In the mosquito, the gametocytes move along with the blood meal to the mosquito's midgut.