Human Anatomy Codexery

Epithelium

Protective layer of cells lining body surfaces and cavities.

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Epithelium is a tissue that lines body surfaces and cavities, with cells arranged in continuous sheets.[1][2] Cell shapes include squamous, cuboidal, and columnar, and layers can be simple (one cell thick) or stratified (multiple cells thick).[3][4]

Quick Facts

Classification
One of four basic animal tissue types
Cell shapes
  • Squamous
  • columnar
  • cuboidal
Layering types
  • Simple
  • stratified
  • pseudostratified
  • transitional
Derived from
All three embryological germ layers (ectoderm, endoderm, mesoderm)

Facts from the source article.

Key facts and history

Simple epithelium has every cell in direct contact with the basement membrane.[5] Stratified epithelium is multilayered and found where linings withstand mechanical or chemical insult.[6] Pseudostratified columnar epithelium appears stratified but is a single layer with nuclei at different heights.[7][8] Epithelia turn over rapidly, with cell division and death balanced mechanically.[9]

Originally, this name referred to the clear covering of small nipple-like tissue found on the lip.[10] Depending on the tension applied, transitional epithelium cells are capable of altering their shape from squamous to cuboidal.[11] In epithelial tissue, cells are arranged very closely together, leaving minimal gaps between them.[2] Following an injury, the basement membrane provides a framework that supports epithelial growth and repair.[12]

Epithelial tissues contain a high number of cell junctions, which control how cells interact with one another.[13]

What the research sources say

That same source states that biochemical markers like cytokeratin are often used to identify epithelial cells, especially when derived from tumors.[14][15] Cancer Research UK classifies carcinomas as cancers originating from epithelium, while sarcomas develop in connective tissue.[16][17] The "Human Anatomy and Physiology" book describes simple epithelium as a single layer where absorption and filtration occur.[18][5] The "Anatomy and Physiology" book explains that stratified epithelium cells flatten as layers become more apical.[19][6]

According to the "Culture of Epithelial Cells" book, when grown in culture, epithelial cells tend to form clusters and display a tight, pavement-like pattern.[14][15]

References

  1. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Anatomy & Physiology", Benjamin Cummings, 2011, p. 133 (original not read by us) en.wikipedia.org
  2. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: Iber, "3D Organisation of Cells in Pseudostratified Epithelia", Frontiers in Physics, 12 May 2022 (original not read by us) en.wikipedia.org
  3. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: Kurn, "Histology, Epithelial Cell", StatPearls, 2025 (original not read by us) en.wikipedia.org
  4. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Dellmann's Textbook of Veterinary Histology", Wiley-Blackwell, 2006, p. 18; "Human Anatomy and Physiology", Benjamin/Cummings, 1995, p. 103–104; "Color atlas of human anatomy: Locomotor system", Thieme, 2008, p. 8 (we also read that source) en.wikipedia.org
  5. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Human Anatomy and Physiology", Benjamin/Cummings, 1995, p. 103–104 (we also read that source) en.wikipedia.org
  6. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Anatomy and Physiology from Science to Life", John Wiley & Sons, 2013, p. 110–115 (we also read that source) en.wikipedia.org
  7. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "From cells to organs: a histology textbook and atlas", Springer, 2002; "Human Anatomy and Physiology", Benjamin/Cummings, 1995, p. 103–104 (we also read that source) en.wikipedia.org
  8. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Permar's oral embryology and microscopic anatomy: a textbook for students in dental hygiene", Lippincott Williams & Wilkins, 2000, p. 9 (original not read by us) en.wikipedia.org
  9. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Mechanical stretch triggers rapid epithelial cell division through Piezo1", Nature, March 2017, p. 118–121; "An epithelial cell destined for apoptosis signals its neighbors to extrude it by an actin- and myosin-dependent mechanism", Current Biology, November 2001, p. 1847–1857; "Crowding induces live cell extrusion to maintain homeostatic cell numbers in epithelia", Nature, April 2012, p. 546–549 (original not read by us) en.wikipedia.org
  10. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: Foster, "On the Term Endothelium", Quarterly Journal of Microscopical Science, 1874, p. 219–223; "Essential IVF: basic research and clinical applications", Kluwer Academic Publishers, 2004, p. 3; (original not read by us) en.wikipedia.org
  11. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Epithelial Cells", AnatomyOne (original not read by us) en.wikipedia.org
  12. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "The nature of disease: pathology for the health professions", Lippincott Williams & Wilkins, 2006, p. 55 (original not read by us) en.wikipedia.org
  13. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Molecular Biology of the Cell", Garland, 2002 (original not read by us) en.wikipedia.org
  14. Open Library record, ISBN 9780471401216 ("Culture of Epithelial Cells"). CC0 (metadata); book content not read. openlibrary.org
  15. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Culture of epithelial cells", John Wiley & Sons, 2002 (we also read that source) en.wikipedia.org
  16. "Types of cancer", Cancer Research UK, 28 October 2014. facts only, no text reused. cancerresearchuk.org
  17. Wikipedia, "Epithelium" (CC BY-SA 4.0), which cites: "Types of cancer", Cancer Research UK, 28 October 2014 (we also read that source) en.wikipedia.org
  18. Open Library record, ISBN 0805342818 ("Human anatomy and physiology"). CC0 (metadata); book content not read. openlibrary.org
  19. Open Library record, ISBN 9781118129203 ("Anatomy and Physiology"). CC0 (metadata); book content not read. openlibrary.org

Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Epithelium (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.

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Sources

Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.

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