These structures correspond to the embryonic foregut. This is a process called foregut fermentation. The esophagus develops as part of the foregut tube. The foregut is split into the cardiac foregut and pyloric foregut. Foregut fermentation is a form of digestion that occurs in the foregut of some animals. Carcinoid tumors, particularly those derived from the embryologic foregut, occur in isolated cases. These receptors are commonly found on tumors located in the foregut, midgut, and hindgut. The junction between the embryological foregut and midgut lies just below the major duodenal papilla. It can be divided into the foregut, midgut and hindgut. These cysts originate from the ventral foregut that forms the respiratory system. Each joins with the foregut through a duct. The junction between the foregut and midgut occurs directly below the major duodenal papilla. The jaw is opposite to the radula and reinforces part of the foregut. These structures usually reside in the thorax, adjacent to the foregut. The contents of the abdomen can be divided into the foregut, midgut, and hindgut.