Editing Spleen (section)

== Function ==

=== Pulp ===
[[File:Spleen hyaloserositis - low mag.jpg|thumb|right|[[Micrograph]] of splenic tissue showing the red pulp (red), white pulp (blue nuclei in lighter background) and a [[hyaloserositis|thickened inflamed capsule]] (mostly pink – top of image). [[H&E stain]].]]

[[File:Red Pulp and White Pulp of the Spleen.jpg|thumb|right|The spleen contains two different tissues, white pulp (A) and red pulp (B). The white pulp functions in producing and growing immune and blood cells. The red pulp functions in filtering blood of antigens, microorganisms, and defective or worn-out red blood cells.]]

{| class="wikitable"
|-
! Area !! Function !! Composition
 |-
 | [[red pulp]] || Mechanical filtration of [[red blood cell]]s. In mice: Reserve of [[monocyte]]s<ref name="Swirski"/>||
* "[[Sinus (anatomy)|sinuses]]" (or "[[Sinusoid (blood vessel)|sinusoid]]s"), which are filled with blood
* "[[splenic cords]]" of [[reticular fiber]]s
* "[[marginal zone]]" bordering on white pulp
 |-
 | [[white pulp]] || Active immune response through humoral and cell-mediated pathways. || Composed of nodules, called [[White pulp|Malpighian corpuscle]]s. These are composed of:
* "[[lymphoid follicles]]" (or "follicles"), rich in [[B cell|B-lymphocytes]]
* "[[periarteriolar lymphoid sheaths]]" (PALS), rich in [[T cell|T-lymphocytes]]
|}

=== Other ===
Other functions of the spleen are less prominent, especially in the healthy adult:
*Spleen produces all types of blood cells during fetal life
* Production of [[opsonin]]s, [[properdin]], and [[tuftsin]].
* Release of [[neutrophil]]s following myocardial infarction.<ref>{{cite web|url=https://academic.oup.com/cardiovascres/advance-article/doi/10.1093/cvr/cvac012/6522118 |title=Rapid neutrophil mobilization by VCAM-1+ endothelial cell-derived extracellular vesicles &#124; Cardiovascular Research &#124; Oxford Academic |publisher=Academic.oup.com |date= |accessdate=2022-02-15}}</ref>
* Creation of [[red blood cell]]s. While the [[bone marrow]] is the primary site of [[hematopoiesis]] in the adult, the spleen has important hematopoietic functions up until the fifth month of gestation. After birth, [[Erythropoiesis|erythropoietic]] functions cease, except in some hematologic disorders. As a major lymphoid organ and a central player in the [[reticuloendothelial system]], the spleen retains the ability to produce lymphocytes and, as such, remains a hematopoietic organ.
* Storage of [[red blood cell]]s, [[lymphocyte]]s and other formed elements. The spleen of horses stores roughly 30 percent of the red blood cells and can release them when needed.<ref name="MSNBC2006-Carey">{{cite news | first=Bjorn | last=Carey | url=http://www.nbcnews.com/id/12648465 | archive-url=https://web.archive.org/web/20150415114535/http://www.nbcnews.com/id/12648465/ | url-status=dead | archive-date=April 15, 2015 | title=Horse science: What makes a Derby winner – Spleen acts as a 'natural blood doper,' scientist says | publisher=NBC News | date=May 5, 2006  | access-date=2006-05-09}}</ref> In humans, up to a cup (240 ml) of red blood cells is held within the spleen and released in cases of [[hypovolemia]]<ref name="Spleen: Information, Surgery and Functions">{{cite web |url=https://chp.edu/CHP/organs+spleen+functions |title=Spleen: Information, Surgery and Functions |publisher=Children's Hospital of Pittsburgh |website= Chp.edu |date=2010-11-17 |access-date=2011-04-03 |url-status=dead |archive-url=https://web.archive.org/web/20110926085253/http://www.chp.edu/CHP/organs+spleen+functions |archive-date=2011-09-26 }}</ref> and [[hypoxia (medical)|hypoxia]].<ref>{{cite journal|last1=Lodin-Sundström|first1=Angelica|last2=Schagatay|first2=Erika|title=Spleen contraction during 20 min normobaric hypoxia and 2 min apnea in humans|journal=Aviation, Space, and Environmental Medicine|date=June 2010|volume=8|issue=6|pages=545–49|doi=10.3357/ASEM.2682.2010|pmid=20540444}}</ref>  It can store [[platelets]] in case of an emergency and also clears old platelets from the circulation. Up to a quarter of [[lymphocytes]] are stored in the spleen at any one time.