The upper gastrointestinal (GI) tract is composed of the oral cavity and salivary glands, the esophagus, stomach, and small intestine (duodenum, jejunum, and ileum). In all three species, the basic mural structure of the tract is maintained. The tract is essentially a smooth muscle-enveloped tube with an innermost mucosa (barrier epithelium, lamina propria, and muscularis mucosae), submucosa, tunica muscularis, and variable serosa or adventitia. The functions of the upper GI tract include transport of the swallowed food bolus, enzymatic digestion, and absorption of nutrients, in addition to protective barrier function against the external environment. The morphological appearance of the different sections of the upper digestive tract reflects the primary function of each segment and is variable between the species.
|Title of host publication||Comparative Anatomy and Histology: a Mouse, Rat and Human Atlas|
|Editors||Piper M. Treuting, Suzanne M. Dint, Kathleen S. Montine|
|Publication status||Published - 22 Sep 2017|