Development of the digestive system As a result of the cephalocaudal and lateral folding of the embryo, a portion of the endoderm-lined yolk sac cavity is incorporated into the embryo to form the primitive gut. In the cephalic and caudal parts of the embryo, the primitive gut forms a tube, the foregut and hindgut, respectively. The middle part, the midgut, remains temporally connected to the yolk sac by means of the vitelline duct. The foregut gives rise to the esophagus, the trachea, lung buds, the stomach, and the duodenum proximal to the entrance of the bile duct. In addition, the liver, pancreas, and biliary apparatus
Human digestive system glands, all of which mainly serve the digestive process, and also play an important role in the maintenance of dental health and general mouth lubrication, without which speech would be impossible. The main glands are all exocrine glands, secreting via ducts. All of these glands terminate in the mouth. The largest of these are the parotid glands—their secretion is mainly serous. The next pair are underneath the jaw, the submandibular glands, these produce both serous fluid and mucus. The serous fluid is produced by serous glands in these salivary glands which also produce lingual lipase. They produce about 70% of