Editing Connective tissue (section)

==Function==
{{See also|Epithelial-mesenchymal transition}}
[[File:Hypermobility-10.jpg|thumb|Hypermobility as a result of an [[Ehlers-Danlos syndromes|inherited connective tissue defect]]]]

Connective tissue has a wide variety of functions that depend on the types of cells and the different classes of fibers involved. [[Loose connective tissue|Loose]] and [[dense irregular connective tissue]], formed mainly by [[fibroblast]]s and [[collagen|collagen fiber]]s, have an important role in providing a medium for oxygen and nutrients to diffuse from [[capillaries]] to cells, and carbon dioxide and waste substances to diffuse from cells back into circulation. They also allow organs to resist stretching and tearing forces. [[Dense regular connective tissue]], which forms organized structures, is a major functional component of [[tendon]]s, [[ligament]]s and [[aponeuroses]], and is also found in highly specialized organs such as the [[cornea]].<ref name="Ross">{{Cite book |last=Ross |first=Michael H. |title=Histology: a text and atlas ; with correlated cell and molecular biology |last2=Pawlina |first2=Wojciech |date=2011 |publisher=Lippincott Williams & Wilkins |isbn=978-0781772006 |edition=6., international |location=Philadelphia, Pa. London |pages=158–173}}</ref> [[Elastic fiber]]s, made from [[elastin]] and [[fibrillin]], also provide resistance to stretch forces.<ref name="Ross" /> They are found in the walls of large blood vessels and in certain ligaments, particularly in the [[ligamenta flava]].<ref name="Ross" />

In [[hematopoiesis|hematopoietic]] and [[lymphatic system|lymphatic]] tissues, [[reticular fiber]]s made by [[reticular cell]]s provide the [[Stroma (animal tissue)|stroma]]—or structural support—for the [[parenchyma]] (that is, the bulk of functional substance) of the organ.<ref name="Ross" />

[[Mesenchyme]] is a type of connective tissue found in the [[Organogenesis|developing organs]] of an [[embryo]] that is capable of [[cellular differentiation|differentiation]] into all types of mature connective tissue.<ref name="wheater">{{Cite book |title=Wheater's Functional Histology: A Text and Colour Atlas |vauthors=Young B, Woodford P, O'Dowd G |publisher=Elsevier |year=2013 |isbn=978-0702047473 |edition=6th |page=65}}</ref> Another type of relatively undifferentiated connective tissue is the '''mucous connective tissue''' known as [[Wharton's jelly]], found inside the [[umbilical cord]].<ref name="Ross" /> This tissue is no longer present after birth, leaving only scattered mesenchymal cells throughout the body.<ref name="Openstax Anatomy & Physiology attribution">{{CC-notice|cc=by4|url=https://openstax.org/books/anatomy-and-physiology/pages/4-3-connective-tissue-supports-and-protects}} {{Cite book |last=Betts |first=J Gordon |title=Anatomy & Physiology |last2=Desaix |first2=Peter |last3=Johnson |first3=Eddie |last4=Johnson |first4=Jody E |last5=Korol |first5=Oksana |last6=Kruse |first6=Dean |last7=Poe |first7=Brandon |last8=Wise |first8=James |last9=Womble |first9=Mark D |date=June 26, 2023 |publisher=OpenStax CNX |isbn=978-1-947172-04-3 |location=Houston |at=4.3 Connective Tissue supports and protects |last10=Young |first10=Kelly A}}</ref>

Various types of specialized tissues and cells are classified under the spectrum of connective tissue, and are as diverse as [[brown adipose tissue|brown]] and [[white adipose tissue]], [[blood]], [[cartilage]] and [[bone]].<ref name="Ross" /> Cells of the immune system—such as [[macrophage]]s, [[mast cell]]s, [[plasma cell]]s, and [[eosinophil]]s—are found scattered in loose connective tissue, providing the ground for starting [[inflammation|inflammatory]] and [[immune system|immune]] responses upon the detection of [[antigen]]s.<ref name="Ross" />