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Grey matter, or gray matter in American English, is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and unmyelinated axons), glial cells (astrocytes and oligodendrocytes), synapses, and capillaries.
Grey matter is composed of cell bodies, dendrites, unmyelinated axons, protoplasmic astrocytes (astrocyte subtype), satellite oligodendrocytes (non-myelinating oligodendrocyte subtype), microglia, and very few myelinated axons. White matter is composed of myelinated axons, fibrous astrocytes, myelinating oligodendrocytes, and microglia.
The outer part of the cerebrum is the cerebral cortex, made up of grey matter arranged in layers. It is 2 to 4 millimetres (0.079 to 0.157 in) thick, and deeply folded to give a convoluted appearance. [21] Beneath the cortex is the cerebral white matter. The largest part of the cerebral cortex is the neocortex, which has six neuronal layers.
Association fibers are axons (nerve fibers) that connect cortical areas within the same cerebral hemisphere. [1]In human neuroanatomy, axons within the brain, can be categorized on the basis of their course and connections as association fibers, projection fibers, and commissural fibers. [1]
Visually, the interior of the brain consists of areas of so-called grey matter, with a dark color, separated by areas of white matter, with a lighter color. Further information can be gained by staining slices of brain tissue with a variety of chemicals that bring out areas where specific types of molecules are present in high concentrations.
The grey columns, (three regions of grey matter) in the center of the cord, is shaped like a butterfly and consists of cell bodies of interneurons, motor neurons, neuroglia cells and unmyelinated axons. The anterior and posterior grey columns present as projections of grey matter and are also known as the horns of the spinal cord.
The neocortex consists of the grey matter, or neuronal cell bodies and unmyelinated fibers, surrounding the deeper white matter (myelinated axons) in the cerebrum. This is a very thin layer though, about 2–4 mm thick. [6] There are two types of cortex in the neocortex, the proisocortex and the true isocortex.
Gray matter, containing numerous cell bodies; White matter, primarily made up of myelinated axons This page was last edited on 8 ...