Jump to content

Intestinal gland

From Wikipedia, the free encyclopedia
(Redirected fromIntestinal crypt)
Intestinal gland
Micrographof thesmall intestinemucosashowing theintestinal glands- bottom 1/3 of image.H&E stain.
Details
Identifiers
Latinglandula intestinalis
TA98A05.6.01.012
A05.7.01.008
TA22942,2969
FMA15052
Anatomical terminology

Inhistology,anintestinal gland(alsocrypt ofLieberkühnandintestinal crypt) is aglandfound in betweenvilliin theintestinal epitheliallining of thesmall intestineandlarge intestine(or colon). The glands and intestinal villi are covered byepithelium,which contains multiple types ofcells:enterocytes(absorbing water and electrolytes),goblet cells(secreting mucus),enteroendocrine cells(secreting hormones), cup cells,myofibroblast,tuft cells,and at the base of the gland,Paneth cells(secreting anti-microbial peptides) andstem cells.

Structure

[edit]

Intestinal glands are found in theepitheliaof thesmall intestine,namely theduodenum,jejunum,andileum,and in thelarge intestine(colon), where they are sometimes calledcolonic crypts.Intestinal glands of the small intestine contain a base of replicatingstem cells,Paneth cellsof theinnate immune system,andgoblet cells,which produce mucus.[1]In the colon, crypts do not have Paneth cells.[2]

Function

[edit]

Theenterocytesin the small intestinalmucosacontaindigestive enzymesthat digest specific foods while they are being absorbed through the epithelium. These enzymes includepeptidase,sucrase,maltase,lactaseand intestinallipase.This is in contrast to thegastric glandsof thestomachwherechief cellssecretepepsinogen.

Also, new epithelium is formed here, which is important because the cells at this site are continuously worn away by the passing food. The basal (further from theintestinal lumen) portion of the crypt contains multipotentstem cells.During eachmitosis,one of the two daughter cells remains in the crypt as a stem cell, while the other differentiates and migrates up the side of the crypt and eventually into thevillus.These stem cells can differentiate into either an absorptive (enterocytes) or secretory (Goblet cells,Paneth cells,enteroendocrine cells) lineages.[3]BothWntandNotchsignaling pathways play a large role in regulating cell proliferation and in intestinalmorphogenesisandhomeostasis.[4]

Loss of proliferation control in the crypts is thought to lead tocolorectal cancer.

Intestinal juice

[edit]

Intestinal juice (also calledsuccus entericus[5]) refers to the clear to pale yellow watery secretions from the glands lining thesmall intestinewalls. TheBrunner's glandssecrete large amounts of alkaline mucus in response to (1) tactile or irritating stimuli on the duodenal mucosa; (2) vagal stimulation, which increases Brunner's glands secretion concurrently with increase in stomach secretion; and (3) gastrointestinal hormones, especiallysecretin.[6]

Its function is to complete the process begun bypancreatic juice;theenzymetrypsinexists in pancreatic juice in the inactive formtrypsinogen,it is activated by the intestinalenterokinasein intestinal juice. Trypsin can then activate other protease enzymes and catalyze the reaction pro-colipase → colipase.Colipaseis necessary, along withbile salts,to enablelipasefunction.[citation needed]

Intestinal juice also containshormones,digestive enzymes,mucus,substances to neutralizehydrochloric acidcoming from thestomach.Variousexopeptidasewhich further digestspolypeptidesintoamino acidscomplete the digestion ofproteins.[citation needed]

Colonic crypts

[edit]
Colonic crypts (intestinal glands) within four tissue sections. In panel A, the bar shows 100μmand allows an estimate of the frequency of crypts in the colonic epithelium. Panel B includes three crypts in cross-section, each with one segment deficient for CCOI expression and at least one crypt, on the right side, undergoing fission into two crypts. Panel C shows, on the left side, a crypt fissioning into two crypts. Panel D shows typical small clusters of two and three CCOI deficient crypts (the bar shows 50 μm). The images were made from original photomicrographs, but panels A, B and D were also included in an article[7]

The intestinal glands in the colon are often referred to as colonic crypts. Theepithelialinner surface of the colon is punctuated by invaginations, the colonic crypts. The colon crypts are shaped like microscopic thick-walled test tubes with a central hole down the length of the tube (the cryptlumen). Four tissue sections are shown here, two (A and B) cut across the long axes of the crypts and two (C and D) cut parallel to the long axes.

In these images the cells have beenstainedto show a brown-orange color if the cells produce amitochondrialprotein calledcytochrome c oxidase subunit I(CCOI or COX-1). Thenucleiof the cells (located at the outer edges of the cells lining the walls of the crypts) are stained blue-gray withhaematoxylin.As seen in panels C and D, crypts are about 75 to about 110 cells long. The average crypt circumference is 23 cells.[8]From the images, an average is shown to be about 1,725 to 2530 cells per colonic crypt. Another measure was attained giving a range of 1500 to 4900 cells per colonic crypt.[9]Cells are produced at the crypt base and migrate upward along the crypt axis before being shed into the coloniclumendays later.[8]There are 5 to 6 stem cells at the bases of the crypts.[8]

As estimated from the image in panel A, there are about 100 colonic crypts per square millimeter of the colonic epithelium.[10]The length of the human colon is, on average 160.5 cm (measured from the bottom of the cecum to the colorectal junction) with a range of 80 cm to 313 cm.[11]The average inner circumference of the colon is 6.2 cm.[10]Thus, the inner surface epithelial area of the human colon has an area, on average, of about 995 cm2,which includes 9,950,000 (close to 10 million) crypts.

In the four tissue sections shown here, many of the intestinal glands have cells with amitochondrial DNAmutation in the CCOI gene and appear mostly white, with their main color being the blue-gray staining of the nuclei. As seen in panel B, a portion of the stem cells of three crypts appear to have a mutation in CCOI, so that 40% to 50% of the cells arising from those stem cells form a white segment in the cross cut area.

Overall, the percentage of crypts deficient for CCOI is less than 1% before age 40, but then increases linearly with age.[7]Colonic crypts deficient for CCOI reaches, on average, 18% in women and 23% in men, by 80–84 years of age.[7]

Crypts of the colon can reproduce by fission, as seen in panel C, where a crypt is dividing to form two crypts, and in panel B where at least one crypt appears to be fissioning. Most crypts deficient in CCOI are in clusters of crypts (clones of crypts) with two or more CCOI-deficient crypts adjacent to each other (see panel D).[7]

Clinical significance

[edit]
Main article:Cryptitis

Cryptinflammationis known ascryptitisand characterized by the presence ofneutrophilsbetween theenterocytes.A severe cryptitis may lead to a cryptabscess.

Pathologic processes that lead to Crohn's disease, i.e. progressive intestinal crypt destruction, are associated with branching of the crypts.

Causes of crypt branching include:

Research

[edit]

Intestinal glands contain adult stem cells referred to asintestinal stem cells.[12]These cells have been used in the field of stem biology to further understandstem cell niches,[13]and to generate intestinalorganoids.[12]

History

[edit]

The crypts of Lieberkühn are named after the eighteenth-century German anatomistJohann Nathanael Lieberkühn.

References

[edit]
  1. ^Deakin, Barbara Young; et al. (2006).Wheater's functional histology: a text and colour atlas.drawings by Philip J. (5th ed.). [Edinburgh?]: Churchill Livingstone/Elsevier.ISBN978-0-4430-6-8508.
  2. ^Gonçalves, Carlos; Bairos, Vasco (2010).Histologia, Texto e Imagens(in Portuguese) (3rd ed.). Imprensa da Universidade de Coimbra. p. 261.ISBN9789892600703.
  3. ^Umar S. Intestinal stem cells. Curr Gastroenterol Rep. 2010;12(5):340-348. doi:10.1007/s11894-010-0130-3
  4. ^Fre S, Pallavi SK, Huyghe M, Laé M, Janssen KP, Robine S, Artavanis-Tsakonas S, Louvard D. Notch and Wnt signals cooperatively control cell proliferation and tumorigenesis in the intestine. Proc Natl Acad Sci U S A. 2009 Apr 14;106(15):6309-14. doi: 10.1073/pnas.0900427106
  5. ^"succus entericus facts, information, pictures | Encyclopedia articles about succus entericus".encyclopedia.Retrieved2017-04-22.
  6. ^Guyton and Hall Textbook of Medical Physiology,11th edition, p. 805
  7. ^abcdBernstein C, Facista A, Nguyen H, Zaitlin B, Hassounah N, Loustaunau C, Payne CM, Banerjee B, Goldschmid S, Tsikitis VL, Krouse R, Bernstein H (2010)."Cancer and age related colonic crypt deficiencies in cytochrome c oxidase I".World J Gastrointest Oncol.2(12): 429–42.doi:10.4251/wjgo.v2.i12.429.PMC3011097.PMID21191537.
  8. ^abcBaker AM, Cereser B, Melton S, Fletcher AG, Rodriguez-Justo M, Tadrous PJ, Humphries A, Elia G, McDonald SA, Wright NA, Simons BD, Jansen M, Graham TA (2014)."Quantification of crypt and stem cell evolution in the normal and neoplastic human colon".Cell Rep.8(4): 940–7.doi:10.1016/j.celrep.2014.07.019.PMC4471679.PMID25127143.
  9. ^Nooteboom M, Johnson R, Taylor RW, Wright NA, Lightowlers RN, Kirkwood TB, Mathers JC, Turnbull DM, Greaves LC (2010)."Age-associated mitochondrial DNA mutations lead to small but significant changes in cell proliferation and apoptosis in human colonic crypts".Aging Cell.9(1): 96–9.doi:10.1111/j.1474-9726.2009.00531.x.PMC2816353.PMID19878146.
  10. ^abNguyen H, Loustaunau C, Facista A, Ramsey L, Hassounah N, Taylor H, Krouse R, Payne CM, Tsikitis VL, Goldschmid S, Banerjee B, Perini RF, Bernstein C (2010)."Deficient Pms2, ERCC1, Ku86, CcOI in field defects during progression to colon cancer".J Vis Exp(41).doi:10.3791/1931.PMC3149991.PMID20689513.
  11. ^Hounnou G, Destrieux C, Desmé J, Bertrand P, Velut S (2002). "Anatomical study of the length of the human intestine".Surg Radiol Anat.24(5): 290–4.doi:10.1007/s00276-002-0057-y.PMID12497219.S2CID33366428.
  12. ^abPastuła A, Middelhoff M, Brandtner A, Tobiasch M, Höhl B, Nuber AH, Quante M (2016)."Three-Dimensional Gastrointestinal Organoid Culture in Combination with Nerves or Fibroblasts: A Method to Characterize the Gastrointestinal Stem Cell Niche".Stem Cells International.2016:1–16.doi:10.1155/2016/3710836.PMC4677245.PMID26697073.
  13. ^Cannataro, Vincent; McKinley, Scott; St. Mary, Colette (2017)."The evolutionary trade-off between stem cell niche size, aging, and tumorigenesis".Evolutionary Applications.10(6): 590–602.doi:10.1111/eva.12476.PMC5469181.PMID28616066.
[edit]
Retrieved from "https://en.wikipedia.org/w/index.php?title=Intestinal_gland&oldid=1248391855"