Gastrointestinal Tract - Mouth Development
Embryology - 16 Jun 2024 Expand to Translate |
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Introduction
The gastrointestinal tract (GIT) arises initially during the process of gastrulation from the endoderm of the trilaminar embryo (week 3) and extends from the buccopharyngeal membrane to the cloacal membrane. The tract and associated organs later have contributions from all the germ cell layers. During the 4th week three distinct regions (fore-, mid- and hind-gut) extend the length of the embryo and will contribute different components of the GIT.
The oral cavity (mouth) is formed following breakdown of the buccopharyngeal membrane (oropharyngeal or oral membrane) and contributed to mainly by the pharynx lying within the pharyngeal arches (More? Head Development). Loss of buccopharyngeal membrane opens the tract to amniotic fluid through the remainder of development, and during the fetal period is actively swallowed.
This current page provides an introductory overview, use the links below for descriptions of specific components and regions as well as developmental abnormalities.
Note that in historic texts the term entoderm is used to describe endoderm and other terminology may also differ from current descriptions.
Some Recent Findings
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More recent papers |
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This table allows an automated computer search of the external PubMed database using the listed "Search term" text link.
More? References | Discussion Page | Journal Searches | 2019 References | 2020 References Search term: Mouth Embryology <pubmed limit=5>Mouth Embryology</pubmed> <pubmed limit=5>Oral Cavity Embryology</pubmed> |
Textbooks
- Human Embryology Larson Chapter 9 p229-260
- The Developing Human: Clinically Oriented Embryology (6th ed.) Moore and Persaud Chapter 12 p271-302
- Before We Are Born (5th ed.) Moore and Persaud Chapter 13 p255-287
- Essentials of Human Embryology Larson Chapter 9 p123-146
- Human Embryology Fitzgerald and Fitzgerald Chapter 19,20 p119-123
More? References | Online Textbooks | Historic Textbooks
UNSW Students | |
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You have access the following online Embryology textbooks through the UNSW Library. | |
Moore, K.L. & Persuad, T.V.N. (2008). The Developing Human: clinically oriented embryology (8th ed.). Philadelphia: Saunders.
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Schoenwolf, G.C., Bleyl, S.B., Brauer, P.R. and Francis-West, P.H. (2009). Larsen’s Human Embryology (4th ed.). New York; Edinburgh: Churchill Livingstone.
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Objectives
- Understanding of germ layer contributions to the early gastrointestinal tract (GIT)
- Understanding of the folding of the GIT
- Understanding of three main GIT embryonic divisions
- Understanding of associated organ development (liver, pancreas, spleen)
- Brief understanding of mechanical changes (rotations) during GIT development
- Brief understanding of gastrointestinal abnormalities
Germ Layer Contributions
- Endoderm - epithelium and associated glands
- Mesoderm (splanchnic) - mesentry, connective tissues, smooth muscle, blood vessels
- Ectoderm (neural crest) - enteric nervous system (neural tube) - extrinsic innervation
Both endoderm and mesoderm will contribute to associated organs.
Gastrointestinal Tract Movies
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Stage 13 (week 5) | Stage 22 (week 8) | Stage 23 (week 8) | GIT Abnormalities Ultrasound |
Foregut
From the oral cavity the next portion of the foregut is initially a single gastrointestinal (oesophagus) and respiratory (trachea) common tube, the pharynx which lies behind the heart. Note that the respiratory tract will form from a ventral bud arising at this level.
- Oral cavity
- Pharynx (esophagus, trachea)
- Respiratory tract
- Stomach
Development Overview
GIT shown in green anchored by dosal and ventral mesogastrium. The space ouside this will be the peritoneal cavity.
Red ring-neural tube with neural crest Blue ring- notocordOrange- somites
Differentiation of associated organs at the level of the forming stomach occurs both dorsally (spleen) and ventrally (liver).
Large blue ring- dorsal aortaDark green ring- Liver
Continued growth of the GIT and the organs leads to organ movements and bending of tract.
Carnegie stage 13 Embryo Overview
Below is an overview of the sections starting at the level of pharynx compressed dorsoventrally, following the GIT through to the rectum. The most obvious feature is that of a continuous tube initially, attached by dorsoventral mesentry. Outside this tube and mesentry (at the levels below the lung buds) is the intraembryonic coelom that will form the peritoneal cavity. The hepatic diverticulum (liver bud) lies under the septum transversum is the earliest associated GIT organ that has differentiated, and now occupies a substantial region of the abdomen. Clicking on sections below will open the original images.
Bifurcation of the pharynx into anterior respiratory and posterior oesophagous. | The stomach forming beneath the lung buds and adjacent to the developing liver. | Below the stomach the GIT has a large dorsal mesogastrium and finer ventral mesogastrium. Associated with the tract is the large portal blood vessel derived from the vitelline circulation. | At the bottom curvature of the embryo the mesentry association with the GIT shows extensive vitelline vessels running out through the umbilicus. The hindgut can then be seen, ending at the common urogenital sinus, the cloaca. |
Innervation
Neural History
- 1857 Meissner was the first to describe a nerve plexus in the submucosa of the bowel wall.
- 1864 Auerbach described the myenteric plexus between the longitudinal and circular muscle layers.
- 1981 LeDouarin describes neural crest contribution to both plexuses.
Molecular
The endoderm of the developing gastrointestinal tract is a source for patterning signals for both within the tract and also for the surrounding organs and tissues.
- Sox2 - expressed in the anterior part of the primitive gut[2]
- Cdx2 - expressed in the posterior part of the primitive gut[2]
- GDNF - regulate migration of enteric neural crest cells[3]
- endothelin - regulate migration of enteric neural crest cells[3]
References
Online Textbooks
- Developmental Biology (6th ed) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000. The Digestive Tube and Its Derivatives | Endodermal development of a human embryo
- The Gastrointestinal Circulation Peter R. Kvietys. San Rafael (CA): Morgan & Claypool Publishers; 2010. Table of Contents
- Motor Function of the Pharynx, Esophagus, and its Sphincters. Mittal RK. San Rafael (CA): Morgan & Claypool Life Sciences; 2011. Table of Contents
- Search NLM Online Textbooks "gastrointestinal tract" : Developmental Biology | Endocrinology | Molecular Biology of the Cell | The Cell- A molecular Approach
Historic Textbooks
- The Elements of Embryology by Foster, M., Balfour, F. M., Sedgwick, A., & Heape, W. (1883) The Alimentary Canal and its Appendages
- Text-Book of the Embryology of Man and Mammals by Dr Oscar Hertwig (1892) The Organs of the Inner Germ-Layer The Alimentary Tube with its Appended Organs
- Atlas of the Development of Man Volume 2 by Julius Kollmann (1907) Gastrointestinal
- Text-Book of Embryology by Bailey, F.R. and Miller, A.M. (1921) Alimentary tube and organs
Historic Disclaimer - information about historic embryology pages |
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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding. (More? Embryology History | Historic Embryology Papers) |
Reviews
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Articles
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Search PubMed
Search Pubmed: Mouth Development | Oral Cavity Development
Additional Images
Terms
Gastrointestinal Tract Terms | ||
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Glossary Links
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Cite this page: Hill, M.A. (2024, June 16) Embryology Gastrointestinal Tract - Mouth Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_-_Mouth_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G