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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.
White matter is the tissue through which messages pass between different areas of grey matter within the central nervous system. The white matter is white because of the fatty substance (myelin) that surrounds the nerve fibers (axons). This myelin is found in almost all long nerve fibers, and acts as an electrical insulation.
In the CNS, grey matter, which contains the synapses, is important for information processing. White matter, containing myelinated axons, connects and facilitates nerve impulse between grey matter areas in the CNS. [14] In the PNS, the ganglion tissue, containing the cell bodies and dendrites, contain relay points for nerve tissue impulses. The ...
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). [11] The CNS is composed of white and gray matter. [9] This can also be seen macroscopically on brain tissue.
Being rich in lipid, myelin appears white, hence the name given to the "white matter" of the CNS. Both CNS white matter tracts (e.g. the optic nerve, corticospinal tract and corpus callosum) and PNS nerves (e.g. the sciatic nerve and the auditory nerve, which also appear white) each comprise thousands to millions of axons, largely aligned in ...
White matter, which is mostly composed of myelinated axons (hence its white color) and glial cells, is generally not considered to be a part of the neuropil. [citation needed] Neuropil (pl. neuropils) comes from the Greek: neuro, meaning "tendon, sinew; nerve" and pilos, meaning "felt". [2] The term's origin can be traced back to the late 19th ...
The central nervous system (CNS) is derived from the ectoderm—the outermost tissue layer of the embryo. In the third week of human embryonic development the neuroectoderm appears and forms the neural plate along the dorsal side of the embryo. The neural plate is the source of the majority of neurons and glial cells of the CNS.
The neurons of the cerebral cortex reside in a thin layer of gray matter, only 2–4 mm thick, at the surface of the brain. [2] Much of the interior volume is occupied by white matter, which consists of long axonal projections to and from the cortical neurons residing near the