Colon nontumor
General
Histology


Topic Completed: 1 May 2013

Revised: 5 December 2019

Copyright: 2003-2019, PathologyOutlines.com, Inc.

PubMed Search: Colon nontumor histology

Hanni Gulwani, M.B.B.S.
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Cite this page: Gulwani H. Histology. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colonhistology.html. Accessed December 13th, 2019.
Definition / general
  • Composed of mucosa, submucosa, muscularis propria (externa) and serosa (perimuscular tissue in rectum)
  • Mucosa: epithelium, lamina propria and muscularis mucosa
  • Epithelium:
    • Low columnar to cuboidal cells
    • Tubules are tightly packed, have straight test tube shape (minimal branching), parallel to each other, straight luminal surface, rest on thin basement membrane, extend to muscularis mucosa; have absorptive cells and goblet cells
    • Crypts open into surface epithelium or into innominate grooves
    • Crypts are surrounded by pericryptal fibroblast sheath (fibroblasts or myofibroblasts, J Clin Pathol 1999;52:785)
    • Crypts also contain precursor cells, endocrine cells and Paneth cells in right sided colon
    • Intestinal crypt is a proliferative compartment, monoclonal, maintained by stem cells
    • Villus represents the differentiated compartment and is polyclonal as it receives cells from multiple crypts
    • Wnt signaling is important for cell proliferation, differentiation, apoptosis along the crypt-villus axis (Stem Cell Rev 2006;2:203, J Pathol 2002;197:492)
    • Paneth cells constitute the niche for Lgr5 stem cells in intestinal crypts (Transl Res 2010;156:180)
    • In colon crypts, CD24+ cells residing between Lgr5 stem cells may represent the Paneth cell equivalents (Nature 2011;469:415)
    • Colon cancer may emerge at niche of tissue stem cells (cancer stem cells) which are LGR5+, Nanong- (Acta Histochem 2013;115:320)
  • Positive stains: CDX2 (sensitive and specific for colon), CK8, CK18, CK19
  • Innominate grooves: mucosal area where several crypts open into one central crypt
  • Lamina propria:
    • Capillaries (uniform), lymphatics just above muscularis mucosa
    • Inflammatory cells present (see below)
  • Muscularis mucosa: thin and regular
  • Submucosa:
    • Loose connective tissue with submucosal plexus of Meissner
    • Minimal inflammatory infiltrate
    • Younger patients may have intramucosal lymphoid aggregates that disrupt muscularis mucosa
  • Muscularis propria: inner circular layer, myenteric plexus of Auerbach, outer longitudinal layer
  • Serosa: single layer of flat to low cuboidal mesothelial cells and adjacent fibroelastic tissue
Types of cells
  • Absorptive cells: eosinophilic cytoplasm, no mucin, shorter microvilli than small intestinal cells, basal nuclei
  • Endocrine cells:
    • Usually at base of crypts
    • Similar to cells in pancreas, lung, thyroid, urethra
    • Contain fine eosinophilic granules with secretory proteins
    • Nuclei are not basal but on luminal side of granules
    • Secretory granules are released at BASAL surface of endocrine cell or along lateral surface; NOT apical; products modulate digestive functions
  • Ganglion cells:
  • Goblet cells: contain ovoid mucoid vacuole
  • Inflammatory cells:
    • Lymphocytes (B & T), intraepithelial lymphocytes only rarely, plasma cells, histiocytes (may contain hemosiderin, mucin or "pseudomelanin" from laxatives), mast cells, occasional eosinophils (varies by geography, Mod Pathol 1997;10:363)
    • Lymphoglandular complexes when lymphoid follicles surround deep crypt epithelium extending into submucosa
    • Neutrophils not normally present
  • Interstitial cells of Cajal:
    • Associated with myenteric (Auerbach/intramuscular) plexus between circular and longitudinal muscle layers
    • Have pacemaker function which facilitates active propagation of electrical events and mediates neurotransmission
    • Have unique ultrastructure on EM with gap junctions between each other and smooth muscle cells
    • Have surface tyrosine kinase receptor c-Kit (CD117) which is essential for their development (Am J Surg Pathol 2003;27:228)
    • Kit ligand provided by neuronal cells or smooth muscle cells (J Physiol 2006;576:653, Sultan Qaboos Univ Med J 2012;12:411)
  • M cells:
  • Paneth cells:
    • Secretory epithelial cells at base of crypts in cecum and ascending colon
    • Considered metaplastic if present elsewhere in colon; granules contain antimicrobial peptides (Trends Microbiol 2004;12:394, J Biol Chem 2000;275:33969)
    • Have basophilic cytoplasm due to rough ER, numerous eosinophilic granules (larger than in endocrine cells)
  • Undifferentiated crypt cells:
    • At base of crypts
    • Precursor to other noninflammatory cells
    • Migration from crypts to surface takes 3 - 8 days
    • Process allows for rapid repair, but also makes cells sensitive to radiation and cancer chemotherapy
Diagrams / tables

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M cells

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Intestinal crypt

Microscopic (histologic) images

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MSH6

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PMS2

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Mucosa and submucosa

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Crypts

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Submucosal plexus of Meissner


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Normal mucosa

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Rectum

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Rectal folds of Morgagni



Pericryptal fibroblast sheath:
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Figures c & d

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Sheath is positive for high molecular weight caldesmon

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Sheath is positive for alpha smooth muscle actin

CDX2



Types of cells:
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Paneth cells

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Intestinal crypt

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