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In the PNS, myelin protein zero (MPZ or P0) has a similar role to that of PLP in the CNS in that it is involved in holding together the multiple concentric layers of glial cell membrane that constitute the myelin sheath. The primary lipid of myelin is a glycolipid called galactocerebroside. The intertwining hydrocarbon chains of sphingomyelin ...
Neurons are the excitable cells of the brain that function by communicating with other neurons and interneurons (via synapses), in neural circuits and larger brain networks. The two main neuronal classes in the cerebral cortex are excitatory projection neurons (around 70-80%) and inhibitory interneurons (around 20–30%). [ 2 ]
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.
Myelin basic protein (MBP) is a protein believed [weasel words] to be important in the process of myelination of nerves in the nervous system. The myelin sheath is a multi-layered membrane, unique to the nervous system, that functions as an insulator to greatly increase the velocity of axonal impulse conduction . [ 5 ]
The neurilemma is underlain by the myelin sheath (also known as the medullary sheath). In the central nervous system, axons are myelinated by oligodendrocytes, thus lack neurilemma. The myelin sheaths of oligodendrocytes do not have neurilemma because excess cytoplasm is directed centrally toward the oligodendrocyte cell body.
The myelin sheath is not continuous but is segmented along the axon's length at gaps known as the nodes of Ranvier. In the peripheral nervous system the myelination of axons is carried out by Schwann cells. [1] Oligodendrocytes are found exclusively in the CNS, which comprises the brain and spinal cord.
Myelin is formed by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.Therefore, the first stage of myelinogenesis is often defined as the differentiation of oligodendrocyte progenitor cells (OPCs) or Schwann cell progenitors into their mature counterparts, [4] followed by myelin formation around axons.
The myelin sheath is a multi-layered membrane, unique to the nervous system, that functions as an insulator to greatly increase the efficiency of axonal impulse conduction. [ 2 ] In humans, point mutations in PLP are the cause of Pelizaeus–Merzbacher disease (PMD), a neurologic disorder of myelin metabolism.