Editing Human brain (section)

===Microanatomy===
The human brain is primarily composed of [[neuron]]s, [[glial cell]]s, [[neural stem cell]]s, and [[blood vessel]]s. Types of neuron include [[interneuron]]s, [[pyramidal cell]]s including [[Betz cell]]s, [[motor neuron]]s ([[upper motor neuron|upper]] and [[lower motor neuron]]s), and cerebellar [[Purkinje cell]]s. Betz cells are the largest cells (by size of cell body) in the nervous system.{{sfn|Purves|2012|p=377}} The adult human brain is estimated to contain 86±8 billion neurons, with a roughly equal number (85±10 billion) of non-neuronal cells.<ref name=":1" /> Out of these neurons, 16 billion (19%) are located in the cerebral cortex, and 69 billion (80%) are in the cerebellum.<ref name="Bigos"/><ref name=":1">{{cite journal |last1=Azevedo |first1=F. |display-authors=etal |title=Equal numbers of neuronal and nonneuronal cells make the human brain an isometrically scaled-up primate brain |journal=The Journal of Comparative Neurology |date=April 10, 2009 |volume=513 |issue=5 |pages=532–541 |doi=10.1002/cne.21974 |quote=despite the widespread quotes that the human brain contains 100 billion neurons and ten times more glial cells, the absolute number of neurons and glial cells in the human brain remains unknown. Here we determine these numbers by using the isotropic fractionator and compare them with the expected values for a human-sized primate. We find that the adult male human brain contains on average 86.1 ± 8.1 billion NeuN-positive cells (“neurons”) and 84.6 ± 9.8 billion NeuN-negative (“nonneuronal”) cells. |pmid=19226510|s2cid=5200449 }}</ref>

Types of glial cell are [[astrocyte]]s (including [[Bergmann glia]]), [[oligodendrocyte]]s, [[ependymal cell]]s (including [[tanycyte]]s), [[radial glial cell]]s, [[microglia]], and a subtype of [[oligodendrocyte progenitor cell]]s. Astrocytes are the largest of the glial cells. They are [[stellate cell]]s with many processes radiating from their [[soma (biology)|cell bodies]]. Some of these processes end as perivascular [[endfeet]] on [[capillary]] walls.<ref>{{Cite book |last1=Pavel |first1=Fiala |last2=Jiří |first2=Valenta |title=Central Nervous System |url=https://books.google.com/books?id=LPlSBAAAQBAJ&pg=PA79 |publisher=Karolinum Press |page=79 |date=January 1, 2013|isbn=978-80-246-2067-1 }}</ref> The [[glia limitans]] of the cortex is made up of [[Astrocyte endfeet|astrocyte endfeet processes]] that serve in part to contain the cells of the brain.<ref name="Anatomy and Ultrastructure"/>

[[Mast cell]]s are [[white blood cell]]s that interact in the [[neuroimmune system]] in the brain.<ref name="Mast cell neuroimmmune system">{{cite journal | last1=Polyzoidis |first1=S. |last2=Koletsa |first2=T. |last3=Panagiotidou |first3=S. |last4=Ashkan |first4=K. |last5=Theoharides |first5=T.C. | title=Mast cells in meningiomas and brain inflammation | journal=Journal of Neuroinflammation | volume=12 | issue=1 | page=170 | year=2015 | pmid=26377554 | pmc=4573939 | doi=10.1186/s12974-015-0388-3 |doi-access=free }}</ref> Mast cells in the central nervous system are present in [[Mast cell#In the nervous system|a number of structures]] including the meninges;<ref name="Mast cell neuroimmmune system" /> they mediate neuroimmune responses in inflammatory conditions and help to maintain the blood–brain barrier, particularly in brain regions where the barrier is absent.<ref name="Mast cell neuroimmmune system" />{{sfn|Guyton & Hall|2011|pp=748–749}} Mast cells serve the same general functions in the body and central nervous system, such as effecting or regulating allergic responses, [[Innate immune system|innate]] and [[Adaptive immune system|adaptive immunity]], [[autoimmunity]], and [[inflammation]].<ref name="Mast cell neuroimmmune system" /> Mast cells serve as the main [[effector cell]] through which pathogens can affect the [[gut-brain axis|biochemical signaling that takes place between the gastrointestinal tract and the central nervous system]].<ref name="pmid24833851">{{cite journal | last1=Budzyński |first1=J |last2=Kłopocka |first2=M. | title=Brain-gut axis in the pathogenesis of Helicobacter pylori infection | journal=World J. Gastroenterol. | volume=20 | issue=18 | pages=5212–25 | year=2014 | pmid=24833851 | pmc=4017036 | doi=10.3748/wjg.v20.i18.5212 |doi-access=free }}</ref><ref name="Microbiome-CNS-ENS">{{cite journal | last1=Carabotti |first1=M. |last2=Scirocco |first2=A. |last3=Maselli |first3=M.A. |last4=Severi |first4=C. | title=The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems | journal=Ann Gastroenterol | volume=28 | issue=2 | pages=203–209 | year=2015 | pmid=25830558 | pmc=4367209}}</ref>

Some 400 [[gene]]s are shown to be brain-specific. In all neurons, [[ELAVL3]] is expressed, and in pyramidal cells, [[NRGN]] and [[REEP2]] are also expressed. [[GAD1]] – essential for the biosynthesis of the neurotransmitter [[GABA]] – is expressed in interneurons. Proteins expressed in glial cells include astrocyte markers [[Glial fibrillary acidic protein|GFAP]] and [[S100B]] whereas [[myelin basic protein]] and the transcription factor [[OLIG2]] are expressed in oligodendrocytes.<ref>{{Cite journal|last1=Sjöstedt|first1=Evelina|last2=Fagerberg|first2=Linn|last3=Hallström|first3=Björn M.|last4=Häggmark|first4=Anna|last5=Mitsios|first5=Nicholas|last6=Nilsson|first6=Peter|last7=Pontén|first7=Fredrik|last8=Hökfelt|first8=Tomas|last9=Uhlén|first9=Mathias|date=June 15, 2015|title=Defining the human brain proteome using transcriptomics and antibody-based profiling with a focus on the cerebral cortex|journal=PLOS ONE |volume=10|issue=6|page=e0130028 |doi=10.1371/journal.pone.0130028|pmid=26076492 |pmc=4468152|issn=1932-6203|bibcode=2015PLoSO..1030028S|doi-access=free}}</ref>