This section of notes gives an introductory overview of intestinal development. In studying this part of the GIT much emphasis is placed upon the initial herniation of the midgut loop during development and its subsequent rotations to achieve the correct anatomical position (More? Abnormalities - Intestinal Malrotation). There is more than the physical looping and you should also consider the differentiating physiological functions of the small and large intestine, their associated vascularisation and mesenteries and associated specialized regions (immune Peyers patches). Finally, consider the early postnatal maturation that occurs with population of the gut with colonizing microbiota (Enterococcus faecalis, etc.) and the role in early immune function in absorbtion of maternal immunoglobulin. (More? Postnatal) |
(Images: modified from Gray's Anatomy) |
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Early GIT structure |
Later GIT structure |
Page Links: Introduction | Some Recent Findings | Midgut Herniation | Duodenum/Pancreas Rotation | GIT Rotation Cartoon | Midgut Mesentery Attachment | Arterial Supply to Mesentery | Peyer's Patches | Enteroendocrine | Postnatal | Movies | References | WWW Links | Glossary
Sangiorgi E, Capecchi MR. Bmi1 is expressed in vivo in intestinal stem cells. Nat Genet. 2008 Jul;40(7):915-20.
"Unexpectedly, the distribution of Bmi1-expressing stem cells along the length of the small intestine suggested that mammals use more than one molecularly distinguishable adult stem cell subpopulation to maintain organ homeostasis."
Natasza A. Kurpios, Marta Ibañes, Nicole M. Davis, Wei Lui, Tamar Katz, James F. Martin, Juan Carlos Izpisúa Belmonte, and Clifford J. Tabin. The direction of gut looping is established by changes in the extracellular matrix and in cell:cell adhesion PNAS 2008 105: 8499-8506; published online on June 23, 2008
"The counterclockwise coiling of the intestines is initiated by a leftward tilt of the primitive gut tube, imparted by left–right asymmetries in the architecture of the dorsal mesentery. ...We find that the dorsal mesentery extracellular matrix is indeed left–right asymmetric and moreover that the adhesion molecule N-cadherin is expressed exclusively on the left side."
Are A, Aronsson L, Wang S, Greicius G, Lee YK, Gustafsson JA, Pettersson S, Arulampalam V. Enterococcus faecalis from newborn babies regulate endogenous PPAR{gamma} activity and IL-10 levels in colonic epithelial cells. Proc Natl Acad Sci U S A. 2008 Jan 30)
After the stomach the initial portion of the GIT tube is the duodenum which initially lies in the midline within the peritoneal cavity, but then (along with the attached pancreas) undergoes rotation to become a retroperitoneal structure.
The diagram below shows this rotation with spinal cord at the top, vertebral body then dorsal aorta then pertioneal wall and cavity.
Rotation of the Duodenum
About the Movie
View from left hand side of embryo facing left. Sequence spans approx 6-11 weeks of development. There is an initial 90 degree rotation followed by 2 more 90 degree rotations to give 270 degrees total. The upper GIT is shader light green, the red vessel is the superior mesenteric artery off the dorsal aorta.
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The diagram shows the anatomical position of mesentery atachment to the posterior peritoneal wall of the small intestine. (More? Intestinal Malrotation) |
outer submucous plexus - (OSP, Meissner’s plexus, Schabadasch plexus) A gastrointestinal tract intrinsic neral network, one of two (inner and outer) within the submucosa involved in intestinal secretion and gut motility in large mammals. Smaller animals have only a single submucous plexus.
Abnormalities
Intestinal neuronal dysplasia type B - (IND B) a disease of the submucous plexus of the intestine. An unknown aetiology theories include fetal/postnatal an intestinal obstruction reaction or inflammatory disease.
Peyer's Patch, adult (Image: UWA Blue Histology)
Fetal Tract Development
Week 11 - villi begin to appear in small intestine, goblet cells
Week 16 - villi in entire intestine
Week 20 - Peyer's patches in small intestine (the adult intestinal immune system includes: Peyer's patches, isolated lymphoid follicles, cryptopatches and mesenteric lymph nodes)
Veiga-Fernandes H, Coles MC, Foster KE, Patel A, Williams A, Natarajan D, Barlow A, Pachnis V, Kioussis D. Tyrosine kinase receptor RET is a key regulator of Peyer's patch organogenesis. Nature. 2007 Mar 29;446(7135):547-51.
Finke D, Kraehenbuhl JP. Formation of Peyer's patches. Curr Opin Genet Dev. 2001 Oct;11(5):561-7.
"Peyer's patches appear around embryonic day 15.5, when the endoderm has undergone transition to a simple epithelium, the lymphatic vessels have reached the intestinal mucosa, and mesenchymal cells have started to form clusters."
Desai S, Loomis Z, Pugh-Bernard A, Schrunk J, Doyle MJ, Minic A, McCoy E, Sussel L. Nkx2.2 regulates cell fate choice in the enteroendocrine cell lineages of the intestine. Dev Biol. 2008 Jan 1;313(1):58-66. Epub 2007 Oct 3.
"Nkx2.2 regulates cell fate choices within the intestinal enteroendocrine population;
...The remaining intestinal cell populations, including the paneth cells, goblet cells and enterocytes appear to be unaffected by the loss of Nkx2.2."
Gut microbiota colonization
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The adult gut contains approx 400 species of commensal bacteria present mainly in the in the colon and ileum. Early postnatally the intestine is still immature and requires population of the gut with colonizing microbiota (Enterococcus faecalis, etc.) which appear to have a role in interacuvely signalling maturation of the gut. (Image: ARS (USA) Photo Library) |
Enterococcus faecalis |
(More? Are A, Aronsson L, Wang S, Greicius G, Lee YK, Gustafsson JA, Pettersson S, Arulampalam V. Enterococcus faecalis from newborn babies regulate endogenous PPAR{gamma} activity and IL-10 levels in colonic epithelial cells. Proc Natl Acad Sci U S A. 2008 Jan 30) |
Gut Immune Function
Maternal passive immunity initially through the placenta is now postnatally replaced by maternal milk immunoglobulin which is absorbed through the gastrointestinal tract, prior to the establishment of a functioning neonatal immune system.
Link: Maternal Immunologic Agents Transferred to the Recipient Infant
Reviews
Rubin DC. Intestinal morphogenesis. Curr Opin Gastroenterol. 2007 Mar;23(2):111-4. Review.
Rautava S, Walker WA. Commensal bacteria and epithelial cross talk in the developing intestine. Curr Gastroenterol Rep. 2007 Oct;9(5):385-92. Review.
Articles
Are A, Aronsson L, Wang S, Greicius G, Lee YK, Gustafsson JA, Pettersson S, Arulampalam V. Enterococcus faecalis from newborn babies regulate endogenous PPAR{gamma} activity and IL-10 levels in colonic epithelial cells. Proc Natl Acad Sci U S A. 2008 Jan 30)
Desai S, Loomis Z, Pugh-Bernard A, Schrunk J, Doyle MJ, Minic A, McCoy E, Sussel L. Nkx2.2 regulates cell fate choice in the enteroendocrine cell lineages of the intestine. Dev Biol. 2008 Jan 1;313(1):58-66. Epub 2007 Oct 3.
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This section of gastrointestinal tract notes gives an overview of intestinal development.
There are many different aspects to be considered when studying intestinal development, olny a few can be covered briefly on this current page.
Please email Dr Mark Hill if you wish to make a comment about this current project.
Lesser Sac 
Lesser Sac