Editing Macrophage (section)

== Development ==
Macrophages that reside in adult healthy tissues either derive from circulating [[Monocyte|monocytes]] or are established before birth and then maintained during adult life independently of monocytes.<ref>{{cite journal | vauthors = Perdiguero EG, Geissmann F | title = The development and maintenance of resident macrophages | journal = Nature Immunology | volume = 17 | issue = 1 | pages = 2–8 | date = January 2016 | pmid = 26681456 | pmc = 4950995 | doi = 10.1038/ni.3341 }}</ref><ref>{{cite journal | vauthors = Ginhoux F, Guilliams M | title = Tissue-Resident Macrophage Ontogeny and Homeostasis | journal = Immunity | volume = 44 | issue = 3 | pages = 439–449 | date = March 2016 | pmid = 26982352 | doi = 10.1016/j.immuni.2016.02.024 | doi-access = free }}</ref> By contrast, most of the macrophages that accumulate at diseased sites typically derive from circulating monocytes.<ref>{{cite journal | vauthors = Pittet MJ, Nahrendorf M, Swirski FK | title = The journey from stem cell to macrophage | journal = Annals of the New York Academy of Sciences | volume = 1319 | issue = 1 | pages = 1–18 | date = June 2014 | pmid = 24673186 | pmc = 4074243 | doi = 10.1111/nyas.12393 | bibcode = 2014NYASA1319....1P }}</ref> [[Leukocyte extravasation]] describes [[monocyte]] entry into damaged tissue through the [[endothelium]] of [[blood vessels]] as they become macrophages. Monocytes are attracted to a damaged site by chemical substances through [[chemotaxis]], triggered by a range of stimuli including damaged cells, pathogens and [[cytokines]] released by macrophages already at the site. At some sites such as the testis, macrophages have been shown to populate the organ through proliferation.<ref>{{cite journal | vauthors = Wang M, Yang Y, Cansever D, Wang Y, Kantores C, Messiaen S, Moison D, Livera G, Chakarov S, Weinberger T, Stremmel C, Fijak M, Klein B, Pleuger C, Lian Z, Ma W, Liu Q, Klee K, Händler K, Ulas T, Schlitzer A, Schultze JL, Becher B, Greter M, Liu Z, Ginhoux F, Epelman S, Schulz C, Meinhardt A, Bhushan S | title = Two populations of self-maintaining monocyte-independent macrophages exist in adult epididymis and testis | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 118 | issue = 1 | pages = e2013686117 | date = January 2021 | pmid = 33372158 | pmc = 7817195 | doi = 10.1073/pnas.2013686117 | bibcode = 2021PNAS..11813686W | doi-access = free }}</ref> Unlike short-lived [[Neutrophil granulocyte|neutrophils]], macrophages survive longer in the body, up to several months.