Editing Lymphatic system (section)

===Other lymphoid tissue===
Lymphoid tissue associated with the lymphatic system is concerned with immune functions in defending the body against [[infection]]s and the spread of [[tumour]]s. It consists of [[connective tissue]] formed of [[reticular fiber]]s, with various types of [[leukocyte]]s (white blood cells), mostly [[lymphocyte]]s enmeshed in it, through which the lymph passes.<ref>{{DorlandsDict|eight/000109096|lymphoid tissue}}</ref> Regions of the lymphoid tissue that are densely packed with lymphocytes are known as ''lymphoid follicles''. Lymphoid tissue can either be structurally well organized as lymph nodes or may consist of loosely organized lymphoid follicles known as the [[mucosa-associated lymphoid tissue]] (MALT).

The [[central nervous system]] also has lymphatic vessels. The search for T cell gateways into and out of the [[meninges]] uncovered functional [[meningeal lymphatic vessels]] lining the [[dural venous sinuses|dural sinuses]], anatomically integrated into the membrane surrounding the brain.<ref name=Neural_immune_system>{{cite journal | vauthors = Louveau A, Smirnov I, Keyes TJ, Eccles JD, Rouhani SJ, Peske JD, Derecki NC, Castle D, Mandell JW, Lee KS, Harris TH, Kipnis J | display-authors = 6 | title = Structural and functional features of central nervous system lymphatic vessels | journal = Nature | volume = 523 | issue = 7560 | pages = 337–41 | date = July 2015 | pmid = 26030524 | pmc = 4506234 | doi = 10.1038/nature14432 | quote = we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction. | bibcode = 2015Natur.523..337L }}
* {{cite web |date=October 3, 2017 |title=NIH researchers uncover drain pipes in our brains |website=National Institutes of Health |url=https://www.nih.gov/news-events/news-releases/nih-researchers-uncover-drain-pipes-our-brains}}</ref>