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Remyelination is the process of propagating oligodendrocyte precursor cells to form oligodendrocytes to create new myelin sheaths on demyelinated axons in the Central nervous system (CNS). This is a process naturally regulated in the body and tends to be very efficient in a healthy CNS. [ 1 ]
Human axon growth rates can reach 2 mm/day in small nerves and 5 mm/day in large nerves. [4] The distal segment, however, experiences Wallerian degeneration within hours of the injury; the axons and myelin degenerate, but the endoneurium remains. In the later stages of regeneration the remaining endoneurial tube directs axon growth back to the ...
Myelin (/ ˈ m aɪ. ə l ɪ n / MY-ə-lin) is a lipid-rich material that surrounds nerve cell axons to insulate them and increase the rate at which electrical impulses (called action potentials) pass along the axon. [1] [2] The myelinated axon can be likened to an electrical wire (the axon) with insulating material (myelin) around it. However ...
Multiple sclerosis (MS) is a chronic disease of the nervous system that can lead to muscle weakness, vision loss, and paralysis. It occurs when the immune system attacks the myelin sheath that ...
In chronic MS lesions where remyelination is incomplete, there is evidence that there are oligodendrocytes with processes extending toward demyelinated axons, but they do not seem to be able to generate new myelin. [63] The mechanisms that regulate differentiation of OPCs into myelinating oligodendrocytes are an active area of research.
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.
A single oligodendrocyte can extend its processes to cover up to 40 axons, that can include multiple adjacent axons. [2] 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]
The unmyelinated, preterminal axons with very long varicose branches are present in small axon bundles and varicose terminal axons are present as single isolated axons. The small axon bundles run parallel to and between muscle bundles and the "en passage" varicose axons are the main sources of innervations to the gut smooth muscle bundles.