Editing Central nervous system (section)

===White and gray matter===
{{main article|Gray matter|White matter}}
[[Image:1202 White and Gray Matter.jpg|thumb|right|Dissection of a human brain with labels showing the clear division between white and gray matter.]]
Microscopically, there are differences between the neurons and tissue of the CNS and the [[peripheral nervous system]] (PNS).<ref>{{cite book | vauthors = Miller AD, Zachary JF | chapter=Nervous System | title = Pathologic Basis of Veterinary Disease. | date=10 May 2020 | pages = 805–907.e1 | doi=10.1016/B978-0-323-35775-3.00014-X | pmc = 7158194 | isbn = 9780323357753 }}</ref> The CNS is composed of [[white matter|white]] and [[gray matter]].<ref name="Kandel" /> This can also be seen macroscopically on brain tissue. The white matter consists of [[axon]]s and [[oligodendrocyte]]s, while the gray matter consists of [[neuron]]s and unmyelinated fibers. Both tissues include a number of [[glia]]l cells (although the white matter contains more), which are often referred to as supporting cells of the CNS. Different forms of glial cells have different functions, some acting almost as scaffolding for [[neuroblast]]s to climb during [[neurogenesis]] such as [[bergmann glia]], while others such as [[microglia]] are a specialized form of [[macrophage]], involved in the [[immune system]] of the brain as well as the clearance of various [[metabolite]]s from the [[brain tissue]].<ref name="Fitzgerald" /> [[Astrocyte]]s may be involved with both clearance of metabolites as well as transport of fuel and various beneficial substances to neurons from the [[capillary|capillaries]] of the brain. Upon CNS injury astrocytes will proliferate, causing [[gliosis]], a form of neuronal scar tissue, lacking in functional neurons.<ref name="Fitzgerald" />

The brain ([[cerebrum]] as well as [[midbrain]] and [[hindbrain]]) consists of a [[Cerebral cortex|cortex]], composed of neuron-bodies constituting gray matter, while internally there is more white matter that form [[Nerve tract|tract]]s and [[commissural fiber|commissures]]. Apart from cortical gray matter there is also [[subcortical gray matter]] making up a large number of different [[Nucleus (neuroanatomy)|nuclei]].<ref name="Kandel" />