Esophageal gland

In humans the glands are known as the esophageal submucosal glands and are a part of the human digestive system.{{cite journal |last1=Abdulnour-Nakhoul |first1=Solange |last2=Nakhoul |first2=Nazih L. |last3=Wheeler |first3=Scott A. |last4=Wang |first4=Paul |last5=Swenson |first5=Eric R. |last6=Orlando |first6=Roy C. |title=HCO 3 − secretion in the esophageal submucosal glands |journal=American Journal of Physiology. Gastrointestinal and Liver Physiology |date=April 2005 |volume=288 |issue=4 |pages=G736–G744 |doi=10.1152/ajpgi.00055.2004}} They are a small compound racemose exocrine glands of the mucous type.{{citation needed|date=May 2017}}

There are two types:

• Esophageal submucosal glands are compound tubulo-alveolar glands. Some serous cells are present. These glands are more numerous in the upper third of the esophagus.{{Cite book|title=Human Histology|last=Nemeskeri|first=Agnes|publisher=Apathy Istvan Foundation, Semmelweis University Budapest, Department of Human Morphology and Developmental Biology|location=Budapest|pages=16}} They secrete acid mucin for lubrication.{{citation needed|date=May 2017}}
• Esophageal cardiac glands- mucous glands located near the cardiac orifice (esophago-gastric junction) in the lamina propria mucosae. They secrete neutral mucin that protects the esophagus from acidic gastric juices. They are simple tubular or branched tubular glands.
• There are also mucous glands present at the pharyngo-esophageal junction in the lamina propria mucosae. These are simple tubular or branched tubular glands.

Each opens upon the surface by a long excretory duct.{{citation needed|date=May 2017}}

The esophageal gland is enlarged in large monoplacophoran species.{{Cite journal| doi = 10.1186/s12862-017-0917-z| pmid = 28249568| pmc = 5333402| issn = 1471-2148| volume = 17| issue = 1| pages = 62| last1 = Chen| first1 = Chong| last2 = Uematsu| first2 = Katsuyuki| last3 = Linse| first3 = Katrin| last4 = Sigwart| first4 = Julia D.| title = By more ways than one: Rapid convergence at hydrothermal vents shown by 3D anatomical reconstruction of Gigantopelta (Mollusca: Neomphalina)| journal = BMC Evolutionary Biology| date = 2017| doi-access = free}}

The esophageal gland or oesophageal pouch is a part of the digestive system of some gastropods. The esophageal gland or pouch is a common feature in so-called basal gastropod clades, including Patelloidea, Vetigastropoda, Cocculiniformia, Neritimorpha and Neomphalina.

The size of the esophageal gland of the scaly-foot gastropod Chrysomallon squamiferum (family Peltospiridae within Neomphalina) is about two orders of magnitude over the usual size. The scaly-foot gastropod houses endosymbiotic bacteria in the esophageal gland. Chrysomallon squamiferum was thought to be the only species of Peltospiridae, that has an enlarged esophageal gland, but later it was shown that both species Gigantopelta the gland also enlarged.{{cite journal | last1 = Chen | first1 = C. | last2 = Linse | first2 = K. | last3 = Roterman | first3 = C. N. | last4 = Copley | first4 = J. T. | last5 = Rogers | first5 = A. D. | year = 2015 | title = A new genus of large hydrothermal vent‐endemic gastropod (Neomphalina: Peltospiridae) | journal = Zoological Journal of the Linnean Society | volume = 175 | issue = 2| pages = 319–335 | doi = 10.1111/zoj.12279 | doi-access = free | url = http://nora.nerc.ac.uk/id/eprint/501741/1/Chen%20et%20al%20in%20press%20Gigantopelta.pdf }} In other peltospirids, the posterior portion of the oesophagus forms a pair of blind mid-oesophageal pouches or gutters extending only to the anterior end of the foot (Rhynchopelta, Peltospira, Nodopelta, Echinopelta, Pachydermia). The same situation is in Melanodrymia within the family Melanodrymiidae. Bathyphytophilidae and Lepetellidae are also known to have enlarged esophageal pouches, however, though not to the extent of Chrysomallon. Both are known to house endosymbiotic bacteria, in the case of bathyphytophilids most likely also in the esophageal glands but in the lepetellids the endosymbionts are spread in the hemocoel.

{{Gray's}}.

This article incorporates Creative Commons (CC-BY-4.0) text from the reference{{cite journal | last1 = Chen | first1 = C. | last2 = Copley | first2 = J. | last3 = Linse | first3 = K. | last4 = Rogers | first4 = A. | last5 = Sigwart | first5 = J. | year = 2015 | title = The heart of a dragon: 3D anatomical reconstruction of the 'scaly-foot gastropod' (Mollusca: Gastropoda: Neomphalina) reveals its extraordinary circulatory system | url =https://eprints.soton.ac.uk/378306/2/s12983-015-0105-1-s1.pdf | journal = Frontiers in Zoology | volume = 12 | page = 13 | doi = 10.1186/s12983-015-0105-1| pmid = 26085836 | pmc=4470333 | doi-access = free }}

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Category:Digestive system

Category:Glands