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This organization demands a tight developmental control and the formation of a variety of specialized zones of contact between different areas of the myelinating cell membrane. Each node of Ranvier is flanked by paranodal regions where helicoidally wrapped glial loops are attached to the axonal membrane by a septate-like junction.
After hip replacement, hip prosthesis zones are regions in the interface between prosthesis material and the surrounding bone. These are used as reference regions when describing for example complications including hip prosthesis loosening on medical imaging .
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.
Subacute combined degeneration of spinal cord, also known as myelosis funiculus, or funicular myelosis, [1] also Lichtheim's disease, [2] [3] and Putnam-Dana syndrome, [4] refers to degeneration of the posterior and lateral columns of the spinal cord as a result of vitamin B 12 deficiency (most common).
The process of generating myelin is called myelination or myelinogenesis. In the CNS, oligodendrocyte progenitor cells (OPCs) differentiate into mature oligodendrocytes, which form myelin. In humans, myelination begins early in the 3rd trimester, [ 11 ] although only little myelin is present in either the CNS or the PNS at the time of birth.
Following terminal differentiation in vivo, mature oligodendrocytes wrap around and myelinate axons. In vitro , oligodendrocytes create an extensive network of myelin-like sheets. The process of differentiation can be observed both through morphological changes and cell surface markers specific to the discrete stage of differentiation, though ...
Myelin debris, present in CNS or PNS, contains several inhibitory factors. The prolonged presence of myelin debris in CNS could possibly hinder the regeneration. [ 22 ] An experiment conducted on newts , animals that have fast CNS axon regeneration capabilities, found that Wallerian degeneration of an optic nerve injury took up to 10 to 14 days ...
Myelination is a process by which axons are covered with a protective substance called myelin that drastically increases the signaling efficiency of the neuron. [7] The arcuate fasciculus is heavily myelinated in healthy adult brains. The density of this myelination has been found to predict the accuracy and speed to which one can comprehend ...