An expanded region of the vertebrate alimentary tract that serves as a food storage compartment and digestive organ. A stomach is lined, in whole or in part by a glandular epithelium.
An expanded region of the vertebrate alimentary tract that serves as a food storage compartment and digestive organ. A stomach is lined, in whole or in part by a glandular epithelium.
Portion of alimentary canal with increased circular and longitudinal smooth muscle. Bounded posteriorly by the pyloric sphincter. Mucosal lining has increased folding.[AAO]
obo_purl:UBPROP_0000003
It appears that the stomach has an ancient origin. The stomach first appears in the fish lineage. The prevertebrate chordates do not have a true stomach, whereas the cartilaginous and bony fish do. Although most fish do have a true stomach, some fish species appear to have lost the stomach secondarily. The remaining vertebrate lineages do have a true stomach (at least in the adult animal), although there is great variation in the size and shape of the stomach.[well established][VHOG]
obo_purl:UBPROP_0000008
We restrict this to the vertebrate specific structure - see the grouping class 'food storage organ' for analogous structures in other species. Teleosts: Zebrafish is functionally stomach-less, but may retain ontogenic footprint. Although the precise shape and size of the stomach varies widely among different vertebrates, the relative positions of the oesophageal and duodenal openings remain relatively constant. As a result, the organ always curves somewhat to the left before curving back to meet the pyloric sphincter. However, lampreys, hagfishes, chimaeras, lungfishes, and some teleost fish have no stomach at all, with the oesophagus opening directly into the intestine. The gastric lining is usually divided into two regions, an anterior portion lined by fundic glands, and a posterior with pyloric glands. Cardiac glands are unique to mammals, and even then are absent in a number of species. The distributions of these glands vary between species, and do not always correspond with the same regions as in man. Furthermore, in many non-human mammals, a portion of the stomach anterior to the cardiac glands is lined with epithelium essentially identical to that of the oesophagus. Ruminants, in particular, have a complex stomach, the first three chambers of which are all lined with oesophageal mucosa
