Digestive system of gastropods species that have undergone de-torsion, however, the oesophagus may open into the anterior of the stomach, which is therefore reversed from the usual gastropod arrangement. In "Tarebia granifera" the brood pouch is above the oesophagus. There is available an extensive rostrum on the anterior part of the oesophagus in all carnivorous gastropods. Some basal gastropod clades have oesophageal gland. In most species, the stomach itself is a relatively simple sac, and is the main site of digestion. In many herbivores, however, the hind part of the oesophagus is enlarged to form a crop, which, in terrestrial pulmonates, may even replace
Development of the digestive system develop as outgrowths of the endodermal epithelium of the upper part of the duodenum. Since the upper part of the foregut is divided by the tracheoesophageal septum into the esophagus posteriorly and the trachea and lung buds anteriorly, deviation of the septum may result in abnormal openings between the trachea and esophagus. The epithelial liver cords and biliary system growing out into the septum transversum differentiate into parenchyma. Hematopoietic cells (present in the liver in greater numbers before birth than afterward), Kupffer cells, and connective tissue cells originate in the mesoderm. The pancreas develops from a ventral bud and a