Gastrointestinal Tract - Pancreas Development: Difference between revisions
Line 122: | Line 122: | ||
== Abnormalities == | == Abnormalities == | ||
Listed below are a number of pancreatic developmental abnormalities, see also the 2003 article "Lifetime consequences of abnormal fetal pancreatic development"<ref><pubmed>16421630</pubmed></ref>. | |||
'''Accessory Pancreatic Tissue''' - pancreatic tissue located in associated gastrointestinal tract tissues/organs such as the wall of the stomach, duodenum, jejunum or Meckel's diverticulum. | '''Accessory Pancreatic Tissue''' - pancreatic tissue located in associated gastrointestinal tract tissues/organs such as the wall of the stomach, duodenum, jejunum or Meckel's diverticulum. | ||
Line 131: | Line 134: | ||
'''Tumours''' - Serous Cystadenoma (endocrine tumour), Somatostatinoma (tumour of delta cell origin), intraductal papillary-mucinous neoplasm | '''Tumours''' - Serous Cystadenoma (endocrine tumour), Somatostatinoma (tumour of delta cell origin), intraductal papillary-mucinous neoplasm | ||
Revision as of 07:12, 28 January 2011
Introduction
This section of notes gives an overview of how the pancreas develops as an exocrine organ associated with the gastrointestinal tract. There is a second description, similar in overview, in relation to the pancreas as an endocrine organ, see Endocrine - Pancreas Development.
At the foregut/midgut junction the septum transversum generates 2 pancreatic buds (dorsal and ventral endoderm) which will fuse to form the pancreas. The dorsal bud arises first and generates most of the pancreas. The ventral bud arises beside the bile duct and forms only part of the head and uncinate process of the pancreas.
Some Recent Findings
Pancreatic Duct[1] "The long-type accessory pancreatic duct represents a continuation of the main duct of the dorsal pancreatic bud. The short-type accessory pancreatic duct is probably formed by the proximal main duct of the dorsal pancreatic bud and its long inferior branch." SOX9[2] "We show that Sox9 maintains pancreatic progenitors by stimulating their proliferation, survival, and persistence in an undifferentiated state. Our finding that SOX9 regulates the Notch-effector HES1 suggests a Notch-dependent mechanism and establishes a possible genetic link between SOX factors and Notch." (More? OMIM Sox9 | Protein Sox9) |
Development Overview
- Functions- exocrine (amylase, alpha-fetoprotein) and endocrine (pancreatic islets)
- Pancreatic buds- endoderm, covered in splanchnic mesoderm
- Pancreatic bud formation - duodenal level endoderm, splanchnic mesoderm forms dorsal and ventral mesentery, dorsal bud (larger, first), ventral bud (smaller, later)
- Duodenum growth/rotation -brings ventral and dorsal buds together, fusion of buds
- Pancreatic duct - ventral bud duct and distal part of dorsal bud, exocrine function
- Islet cells- cords of endodermal cells form ducts, which cells bud off to form islets
- Week 7 to 20 - pancreatic hormones secretion increases, small amount maternal insulin
- Week 10 - glucagon (alpha) differentiate first, somatostatin (delta), insulin (beta) cells differentiate, insulin secretion begins
- Week 15 - glucagon detectable in fetal plasma
- Beta cells - stimulate fetal growth, continue to proliferate through to postnatal in infancy, most abundant
- Maternal diabetes mellitus - hypertrophy of fetal beta cells
Late Embryo Pancreas (Carnegie stage 22)
Pancreatic Duct
The pancreatic duct is associated with the gastrointestinal tract exocrine function of the pancreas and is covered in detail in [git9.htm#Pancreatic_Duct_Variations Gastrointestinal Tract Pancreas - Pancreatic Duct Variations].
The pancreatic duct(s) exist as a number of anatomical variations due to the embryological origin from the dorsal and ventral panceas buds formation and later fusion.
Pancreas Histology
File:Pan20he.jpg | File:Pan40ic.jpg |
(Human, H&E) | (Rat, immunohistochemistry) |
(More? [git9.htm#Histology Pancreas Exocrine Histology]) | (Images: Lutz Slomianka, [../People.htm#Blue_Histology UWA Blue Histology]) |
Pancreas History
1642 - main pancreatic duct (MPD) discovered by Johann Georg Wirsung (1589 - 1643) a German physician who worked as a prosector in Padua. The duct is also called Wirsung's duct.
1724 - accessory pancreatic duct (APD) dissected and delineated by Giovanni Domenico Santorini (1681 - 1737) an Italian anatomist. The duct is also called Santorini's duct.
1833 - Amylase, the form enzyme also found in exocrine pancreas, isolated from a malt solution by Anselme Payen.
1893 - Islets of Langerhans named in honour of Paul Langerhans (1847-1888) by Gustave-Edouard Laguesse (1861-1927) a french histopathologist.
1922 - discovery of insulin by Frederick Banting and John Macleod, two Canadian researchers, and they subsequently win the 1923 Nobel Prize in Medicine. Banting shared his part of the prize money with a younger coworker Charles Best.
1953 - glucagon, originally called "hyperglycemic glycogenolytic factor", purified by Staub, Sinn and Behrens.[3] [4][5]See also book JM. Howard and W, Hess (2002) "History of the Pancreas: Mysteries of a Hidden Organ".
- Links: Nobel Lecture, September 15, 1925 | Amazon - History of the Pancreas: Mysteries of a Hidden Organ | PDF Article - Purification and Crystallization of Glucagon |
Pancreas Digestive
The digestive function of the pancreas is covered in [git9.htm GIT Notes- Pancreas]
- Pancreatic buds- endoderm, covered in splanchnic mesoderm
- Pancreatic bud formation – duodenal level endoderm, splanchnic mesoderm forms dorsal and ventral mesentery, dorsal bud (larger, first), ventral bud (smaller, later)
- Duodenum growth/rotation – brings ventral and dorsal buds together, fusion of buds
- Pancreatic duct – ventral bud duct and distal part of dorsal bud, exocrine function
Functions - exocrine (amylase, alpha-fetoprotein)
Pancreatic amylase digests starch to maltose. Postnatally, a blood test to detect amylase can be used to diagnose and monitor acute or chronic pancreatitis (pancreas inflammation).
Pancreatic alpha-fetoprotein has been found to change in expression level (in rats) during developent and has been suggested to influence pancreas development.
Liu L, Guo J, Yuan L, Cheng M, Cao L, Shi H, Tong H, Wang N, De W. Alpha-fetoprotein is dynamically expressed in rat pancreas during development. Dev Growth Differ. 2007 Oct;49(8):669-81.
"Immunolocalization for AFP revealed that a positive reactivity was detectable at E15.5 pancreas, became stronger in the cytoplasm of mesenchyme cells at E18.5, and declined after birth to a nearly undetectable level in adults."
Duodenum/Pancreas Rotation
After the stomach the initial portion of the gastrointestinal tract tube is the duodenum which initially lies in the midline within the peritoneal cavity.
This region, along with the attached pancreas, undergoes rotation to become a retroperitoneal structure. This diagram shows the rotation with spinal cord at the top, vertebral body then dorsal aorta then pertioneal wall and cavity. Note this is a simplified diagram and the liver would push everything to the left during this rotation. |
Mouse Pancreas Development
- Pancreas develops from distinct dorsal and ventral primordia.
- Dorsal pancreas - midline endoderm in posterior foregut is a single layer of epithelial cells that contacts notochord, an axial mesoderm-derived structure
- Ventral pancreas - Laterally, endoderm fated to form ventral pancreas is adjacent to both splanchnic mesoderm and aortic endothelial cells but is not in direct contact with notochord.
- The notochord and dorsal prepancreatic endoderms remain in contact until about the 13-somite stage in mice, 8.5 d postcoitum (dpc), when midline fusion of the paired dorsal aortas occurs.
- The first indication of morphogenesis occurs at 22-25 somites in mice (9.5 dpc)
- dorsal mesenchyme condenses and underlying endoderm evaginates, forming a recognizable dorsal pancreatic bud
- the ventral bud appears later at ~30 somites (10.25-10.5 dpc). Stimulated by mesenchymal signals, pancreatic epithelial cells proliferate and branch.
- The accumulated evidence is consistent with the possibility that a unique cell gives rise to all pancreatic cell lineages. The existence of such a pancreatic "stem" cell remains debatable.
(text modified from Seung K. Kim and Matthias Hebrok Intercellular signals regulating pancreas development and function. Genes & Development 15:111-127 2001)
Duct Development
Abnormalities
Listed below are a number of pancreatic developmental abnormalities, see also the 2003 article "Lifetime consequences of abnormal fetal pancreatic development"[6].
Accessory Pancreatic Tissue - pancreatic tissue located in associated gastrointestinal tract tissues/organs such as the wall of the stomach, duodenum, jejunum or Meckel's diverticulum.
Annular Pancreas - (1 in 7,000 people) pancreas forms as a "ring" of tissue surrounding the duodenum which is subsequently narrowed.
Diabetes Mellitus - Maternal diabetes (and hyperglycaemia) have been shown to lead to increased fetal islet hyperplasia of the insulin producing beta cells and insulin secretion.
Intrauterine growth restriction - can lead to a delayed development of the insulin producing beta cells and low insulin secretion.
Tumours - Serous Cystadenoma (endocrine tumour), Somatostatinoma (tumour of delta cell origin), intraductal papillary-mucinous neoplasm
References
Journals
- Pancreas The official journal of the American Pancreatic Association and the Japan Pancreas Society
- Pancreatology Official Journal of the International Association of Pancreatology (IAP); European Pancreatic Club (EPC)and 16 other societies and study groups.
- Journal of the Pancreas electronic journal of pancreatology
Online Textbooks
Endocrinology: An Integrated Approach Nussey, S.S. and Whitehead, S.A. Oxford, UK: BIOS Scientific Publishers, Ltd; 2001. table of Contents
NIH Genes & Disease Chapter 41 - Endocrine
Pathophysiology of the Endocrine System The Endocrine Pancreas
Developmental Biology (6th ed) Gilbert, Scott F. Sunderland (MA): Sinauer Associates, Inc.; c2000.
Molecular Biology of the Cell (4th Edn) Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. New York: Garland Publishing; 2002. table 15-1. Some Hormone-induced Cell Responses Mediated by Cyclic AMP
Health Services/Technology Assessment Text (HSTAT) Bethesda (MD): National Library of Medicine (US), 2003 Oct.
Search NLM Online Textbooks- "pancreas development" : Endocrinology | Molecular Biology of the Cell | The Cell- A molecular Approach
Search Bookshelf Pancreas Development
Search Pubmed
Search Pubmed Now: Pancreas Development | Exocrine Pancreas Development
Glossary Links
- Glossary: A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z | Numbers | Symbols | Term Link
Cite this page: Hill, M.A. (2024, June 14) Embryology Gastrointestinal Tract - Pancreas Development. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Gastrointestinal_Tract_-_Pancreas_Development
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G