Gastrointestinal Tract Development: Difference between revisions
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Revision as of 08:15, 13 May 2010
Introduction
The gastrointestinal tract (GIT) extending from the buccopharyngeal membrane to the cloacal membrane arises initially from the endoderm of the trilaminar embryo (week 2, 3). It later has contributions from all the germ cell layers.
During the 4th week the 3 distinct portions (fore-, mid- and hind-gut) extend the length of the embryo and will contribute different components of the GIT. The large mid-gut is generated by lateral embryonic folding which "pinches off" a pocket of the yolk sac, the 2 compartments continue to communicate through the vitelline duct. On this current page there is a brief developmental overview and stage 13/14 embryo overview.
The oral cavity (mouth) is formed following breakdown of the buccopharyngeal membrane (oropharyngeal or oral) and contributed to mainly by the pharynx lying within the pharyngeal arches. The opening of the GIT means that it contains amniotic fluid, which is also swallowed later in development. (More? Taste | Head and Neck Development - Tongue)
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 (More? Respiratory)
--Mark Hill 09:25, 14 April 2010 (EST) Page Template only - content from original UNSW Embryology site currently being edited and updated.
System Links: Introduction | Cardiovascular | Coelomic Cavity | Endocrine | Gastrointestinal Tract | Genital | Head | Immune | Integumentary | Musculoskeletal | Neural | Neural Crest | Placenta | Renal | Respiratory | Sensory | Birth |
Some Recent Findings
GIT Foregut
File:Gitbpmsm.gif | Foregut - beneath the transverse septum the tract grows rapildy, dilating and rotaing to form the primitive stomach. Growth and rotation generates curvatures, peritoneal sacs and a large attached omentum (More? [git10.htm Stomach Development]).
The hepatic diverticulum (liver bud) lies under the septum transversum and is the earliest associated GIT organ that has differentiated, and will occupy a substantial region of the abdomen during development. (More? [git7.htm Liver Development])
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GIT Midgut
File:Git17mm sm.jpg | Midgut - beneath the stomach the initial portion of the small intestine, the duodenum, and the associated pancreas now lie.
Much of the midgut is herniated at the umbilicus external to the abdomen through development. A key step in development is the rotation of this midgut that must occur to place the GIT in the correct abdominal position with its associated mesentry. The GIT itself differentiates to form significantly different structures along its length: oesophagus, stomach, duodenum, jejunum, iliem (small intestine), colon (large intestine). (More? [git13.htm Intestine Development]) The mesentries of the GIT are generated from the common dorsal mesentry, with the ventral mesentry contributing to the lesser omentum and falciform ligament.
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The pancreas arises from 2 sources: the hepatic diverticulum (ventral) and the duodenum (dorsal). The pancreas must also differentiate to establish specific cells for endocrine and exocrine function. (More? [git9.htm Pancreas Development])
The spleen arises in week 5 within the dorsal mesogastrium as proliferating mesenchyme. Cells required for its hemopoietic function arise from the yolk sac wall and near dorsal aorta. The spleen generates both red and white cells in the 2nd trimester. Note that many embryonic RBCs remain nucleated. (More? [git8.htm Spleen Development])
GIT Hindgut
File:Git17mm sm.jpg | Hindgut - distral transverse colon, descending colon, sigmoid colon, rectum and cloaca.
The cloaca is the common urogenital sinus which will later become partitioned into an anterior urinary and posterior GIT rectal component. (More? [urogen.htm Urogenital Development]) |
Reading
* Human Embryology (2nd ed.) Larson Ch9 p229-260
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File:Git17mm sm.jpg |
Objectives
- Name the adult structures developed from the fore-, mid- and hind-gut and list their arterial supply.
- Explain the elongation and rotation of the mid-gut and appreciate the consequences of malrotation.
- Describe the development of the nerve supply (enteric nervous system) of the gut.
- Describe the development of the associated organs, liver and pancreas, and state the functions of these organs in the embryo and fetus.
- Summarise the formation of the adult mesenteries of the gut.
- Describe the developmental abnormalities responsible for the following selected congenital malformations
- Meckel's diverticulum
- Intestinal malrotation (situs inversus)
- Hirschsprung's disease (aganglionic colon)
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 crestBlue 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.
Other Images: [git5.htm#gitrotate Simple cartoon of GIT Rotation] | [git10.htm#Greater_Omentum Greater Omentum] | [git10.htm#Duodenum/Pancreas_Rotation Duodenum/Pancreas Rotation] |
Carnegie stage 13/14 Embryo (Pig) 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. A full description of each image is on the [git3.htm#Pig stage13/14 page.] Clicking on sections below will open the original images.
File:Git.gif | |||
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. |
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
- Search NLM Online Textbooks "gastrointestinal tract" : Developmental Biology | Endocrinology | Molecular Biology of the Cell | The Cell- A molecular Approach
Reviews
- Young HM. On the outside looking in: longitudinal muscle development in the gut. Neurogastroenterol Motil. 2008 May;20(5):431-3.
- Neu J. Gastrointestinal development and meeting the nutritional needs of premature infants. Am J Clin Nutr. 2007 Feb;85(2):629S-634S.
- Anderson RB, Newgreen DF, Young HM. Neural crest and the development of the enteric nervous system. Adv Exp Med Biol. 2006;589:181-96.
- Costa RH, Kalinichenko VV, Holterman AX, Wang X. Transcription factors in liver development, differentiation, and regeneration. Hepatology. 2003 Dec;38(6):1331-47.
- de Santa Barbara P, van den Brink GR, Roberts DJ. Development and differentiation of the intestinal epithelium. Cell Mol Life Sci. 2003 Jul;60(7):1322-32.
- Johnson LR. Functional development of the stomach. Annu Rev Physiol. 1985;47:199-215. Review.
Articles
- Wilm B, Ipenberg A, Hastie ND, Burch JB, Bader DM. The serosal mesothelium is a major source of smooth muscle cells of the gut vasculature. Development. 2005 Dec;132(23):5317-28.
"Our studies show that the gut is initially devoid of a mesothelium but that serosal mesothelial cells expressing the Wilm's tumor protein (Wt1) move to and over the gut. Subsequently, a subset of these cells undergoes epithelial-mesenchymal transition (EMT) and migrates throughout the gut. ...these cells differentiate to smooth muscle of all major blood vessels in the mesenteries and gut."
Search Mar 2007 "gastrointestinal tract development" 29,361 reference articles of which 3,494 were reviews. (More? [../Refer/ncrest/select.htm Neural Crest Reviews References 1999])
Search PubMed
Search April 2010 "Gastrointestinal Tract Development" - All (35980) Review (4707) Free Full Text (8086)
Search Pubmed: Gastrointestinal Tract Development
Additional Images
Terms
Glossary Links
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Cite this page: Hill, M.A. (2024, June 10) Embryology Gastrointestinal Tract Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G