Editing Anatomy (section)

===Epithelium===
[[File:Normal gastric mucosa low mag.jpg|thumb|right|Gastric mucosa at low magnification ([[H&E stain]])]]
[[Epithelial tissue]] is composed of closely packed cells, bound to each other by [[cell adhesion molecule]]s, with little intercellular space. Epithelial cells can be [[Squamous epithelial cell|squamous]] (flat), [[Simple cuboidal epithelium|cuboidal]] or [[Columnar epithelial cell|columnar]] and rest on a [[basal lamina]], the upper layer of the [[basement membrane]],<ref>{{cite book|last=Dorland's|title=Illustrated Medical Dictionary|date=2012|publisher=Elsevier Saunders|isbn=978-1-4160-6257-8|page=203}}</ref> the lower layer is the reticular lamina lying next to the connective tissue in the extracellular matrix secreted by the epithelial cells.<ref>{{cite book|last=Dorland's|title=Illustrated Medical Dictionary|date=2012|publisher=Elsevier Saunders|isbn=978-1-4160-6257-8|page=1002}}</ref> There are many different types of epithelium, modified to suit a particular function. In the [[respiratory tract]] there is a type of [[pseudostratified ciliated columnar epithelium|ciliated]] epithelial lining; in the small intestine there are [[microvilli]] on the epithelial lining and in the large intestine there are [[intestinal villi]]. Skin consists of an outer layer of [[keratin]]ized stratified squamous epithelium that covers the exterior of the vertebrate body. [[Keratinocyte]]s make up to 95% of the cells in the [[epidermis (skin)|skin]].<ref>McGrath, J.A.; Eady, R.A.; Pope, F.M. (2004). Rook's Textbook of Dermatology (7th ed.). Blackwell Publishing. pp. 3.1–3.6. {{ISBN|978-0-632-06429-8}}.</ref> The epithelial cells on the external surface of the body typically secrete an extracellular matrix in the form of a [[cuticle]]. In simple animals this may just be a coat of [[glycoproteins]].<ref name="Ruppert60" /> In more advanced animals, many [[gland]]s are formed of epithelial cells.<ref>{{cite web |url=https://www.bio.davidson.edu/people/kabernd/BerndCV/Lab/EpithelialInfoWeb/Glandular%20Epithelium.html |title=Glandular epithelium |last=Bernd |first=Karen |year=2010 |work=Epithelial Cells |publisher=Davidson College |access-date=25 June 2013 |archive-url=https://web.archive.org/web/20200128053412/https://www.bio.davidson.edu/people/kabernd/BerndCV/Lab/EpithelialInfoWeb/Glandular%20Epithelium.html |archive-date=28 January 2020 |url-status=live }}</ref>