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Grey matter or gray matter is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astroglia and oligodendrocytes), synapses, and capillaries. Grey matter is distinguished from white matter, in that grey matter contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively very few cell bodies and is composed chiefly of long-range myelinated axon tracts. The color difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a very light grey color with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.〔Kolb & Whishaw: Fundamentals of Human Neuropsychology (2003) page 49〕 ==Structure== Grey matter refers to unmyelinated neurons and other cells of the central nervous system. It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord. Grey matter is distributed at the surface of the cerebral hemispheres (cerebral cortex) and of the cerebellum (cerebellar cortex), as well as in the depths of the cerebrum (thalamus; hypothalamus; subthalamus, basal ganglia – putamen, globus pallidus, nucleus accumbens; septal nuclei), cerebellar (deep cerebellar nuclei – dentate nucleus, globose nucleus, emboliform nucleus, fastigial nucleus), brainstem (substantia nigra, red nucleus, olivary nuclei, cranial nerve nuclei). Grey matter in the spinal cord is known as the grey column which travels down the spinal cord distributed in three grey columns that are presented in an "H" shape. The forward-facing column is the anterior grey column, the rear-facing one is the posterior grey column and the interlinking one is the lateral grey column. The grey matter on the left and right side is connected by the gray commissure. The grey matter in the spinal cord consists of interneurons, as well as cell bodies. File:Cervical_vertebra_english.png|Diagram of a spinal vertebra. The grey matter is in the central part of the spinal cord. File:Medulla spinalis - Section - English.svg|Cross-section of spinal cord with grey matter labelled. Grey matter undergoes development and growth throughout childhood and adolescence. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「grey matter」の詳細全文を読む スポンサード リンク
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