Editing Lymphatic system (section)

====Spleen====
{{Main|Spleen}}
The main functions of the spleen are:
# to produce [[immune cell]]s to fight [[antigen]]s
# to remove [[particulate matter]] and aged blood cells, mainly [[red blood cell]]s
# to produce blood cells during fetal life.

The spleen synthesizes [[antibodies]] in its [[white pulp]] and removes antibody-coated bacteria and antibody-coated blood cells by way of blood and [[lymph node]] circulation. The white pulp of the spleen provides immune function due to the lymphocytes that are housed there. The spleen also consists of red pulp which is responsible for getting rid of aged red blood cells, as well as pathogens. This is carried out by macrophages present in the red pulp. A study published in 2009 using mice found that the spleen contains, in its reserve, half of the body's [[monocyte]]s within the [[red pulp]].<ref name="Swirski">{{cite journal | vauthors = Swirski FK, Nahrendorf M, Etzrodt M, Wildgruber M, Cortez-Retamozo V, Panizzi P, Figueiredo JL, Kohler RH, Chudnovskiy A, Waterman P, Aikawa E, Mempel TR, Libby P, Weissleder R, Pittet MJ | display-authors = 6 | title = Identification of splenic reservoir monocytes and their deployment to inflammatory sites | journal = Science | volume = 325 | issue = 5940 | pages = 612–6 | date = July 2009 | pmid = 19644120 | pmc = 2803111 | doi = 10.1126/science.1175202 | bibcode = 2009Sci...325..612S }}</ref> These monocytes, upon moving to injured tissue (such as the heart), turn into [[dendritic cell]]s and [[macrophage]]s while promoting tissue healing.<ref name="Swirski" /><ref name="Jia">{{cite journal | vauthors = Jia T, Pamer EG | title = Immunology. Dispensable but not irrelevant | journal = Science | volume = 325 | issue = 5940 | pages = 549–50 | date = July 2009 | pmid = 19644100 | pmc = 2917045 | doi = 10.1126/science.1178329 | bibcode = 2009Sci...325..549J }}</ref><ref>{{cite web |url=https://www.nytimes.com/2009/08/04/science/04angier.html |title=Finally, the Spleen Gets Some Respect |first=Natalie |last=Angier | name-list-style = vanc |work=The New York Times |date=August 3, 2009 |url-status=live |archive-url=https://web.archive.org/web/20180127113051/https://www.nytimes.com/2009/08/04/science/04angier.html |archive-date=2018-01-27}}</ref> The spleen is a center of activity of the [[mononuclear phagocyte system]] and can be considered analogous to a large lymph node, as its absence causes a predisposition to certain [[infection]]s. Notably, the spleen is important for a multitude of functions. The spleen removes pathogens and old erythrocytes from the blood (red pulp) and produces lymphocytes for immune response (white pulp). The spleen also is responsible for recycling some erythrocytes components and discarding others. For example, hemoglobin is broken down into amino acids that are reused.

Research on [[bony fish]] has shown that a high concentration of T cells are found in the white pulp of the spleen.<ref name="Koppang"/>

Like the [[thymus]], the spleen has only [[efferent lymphatic vessels]]. Both the [[short gastric arteries]] and the [[splenic artery]] supply it with blood.<ref>{{Cite book | publisher = Lippincott Williams & Wilkins | isbn = 978-0-7817-7076-7 | last = Blackbourne | first = Lorne H | name-list-style = vanc | title = Surgical recall | date = 2008-04-01 | page = [https://archive.org/details/surgicalrecall00blac/page/259 259] | url = https://archive.org/details/surgicalrecall00blac/page/259 }}</ref> The [[germinal centers]] are supplied by [[arteriole]]s called ''penicilliary radicles''.<ref>{{cite web |url=http://medical-dictionary.thefreedictionary.com/penicilliary+radicles |title=Penicilliary radicles |work=Saunders Comprehensive Veterinary Dictionary |edition=3rd |year=2007 |publisher=Elsevier, Inc. |via=The Free Dictionary by Farlex |access-date=2011-04-03 |archive-url=https://web.archive.org/web/20160304110148/http://medical-dictionary.thefreedictionary.com/penicilliary+radicles |archive-date=2016-03-04 |url-status=dead }}</ref>

In the human until the fifth month of [[prenatal development]], the spleen creates [[red blood cells]]; after birth, the [[bone marrow]] is solely responsible for [[hematopoiesis]]. As a major lymphoid organ and a central player in the reticuloendothelial system, the spleen retains the ability to produce lymphocytes. The spleen stores [[red blood cells]] and lymphocytes. It can store enough blood cells to help in an emergency. Up to 25% of lymphocytes can be stored at any one time.<ref name="Spleen: Information, Surgery and Functions">{{cite web |url=https://chp.edu/CHP/organs+spleen+functions |archive-url=https://web.archive.org/web/20110926085253/http://www.chp.edu/CHP/organs+spleen+functions |url-status=dead |archive-date=2011-09-26 |title=Spleen: Information, Surgery and Functions |publisher=Children's Hospital of Pittsburgh - Chp.edu |date=2010-11-17 |access-date=2011-04-03 }}</ref>