The intermediate dense line of the myelin sheath is preferentially accessible to cations and is stabilized by cations

1990 ◽  
Vol 19 (2) ◽  
pp. 242-252 ◽  
Author(s):  
S. Ropte ◽  
P. Scheidt ◽  
R. L. Friede
Keyword(s):  
Myelin Sheath ◽  
Dense Line

scholarly journals Myelin sheath structure and regeneration in peripheral nerve injury repair

2019 ◽  
Vol 116 (44) ◽  
pp. 22347-22352 ◽  
Author(s):  
Bin Liu ◽  
Wang Xin ◽  
Jian-Rong Tan ◽  
Rui-Ping Zhu ◽  
Ting Li ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Nerve Injury ◽  
Myelin Sheath ◽  
Peripheral Nerves ◽  
Basic Protein ◽  
Neurological Diseases ◽  
Oculomotor Nerve ◽  
Dense Line ◽  
Transmission Electron ◽  
Sheath Structure

Observing the structure and regeneration of the myelin sheath in peripheral nerves following injury and during repair would help in understanding the pathogenesis and treatment of neurological diseases caused by an abnormal myelin sheath. In the present study, transmission electron microscopy, immunofluorescence staining, and transcriptome analyses were used to investigate the structure and regeneration of the myelin sheath after end-to-end anastomosis, autologous nerve transplantation, and nerve tube transplantation in a rat model of sciatic nerve injury, with normal optic nerve, oculomotor nerve, sciatic nerve, and Schwann cells used as controls. The results suggested that the double-bilayer was the structural unit that constituted the myelin sheath. The major feature during regeneration was the compaction of the myelin sheath, wherein the distance between the 2 layers of cell membrane in the double-bilayer became shorter and the adjacent double-bilayers tightly closed together and formed the major dense line. The expression level of myelin basic protein was positively correlated with the formation of the major dense line, and the compacted myelin sheath could not be formed without the anchoring of the lipophilin particles to the myelin sheath.

scholarly journals The Structure of Myelin Sheaths in the Central Nervous System of Xenopus laevis (Daudin)

1960 ◽  
Vol 7 (1) ◽  
pp. 121-126 ◽  
Author(s):  
A. Peters
Keyword(s):  
Xenopus Laevis ◽  
Myelin Sheath ◽  
Cytoplasmic Process ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
Outer Line ◽  
Myelin Sheaths ◽  
Dense Line ◽  
Central Myelin ◽  
The Central Nervous System

The structure of myelinated nerve fibres has been studied in the spinal cord and optic nerve of the tadpoles of Xenopus laevis. Potassium permanganate-fixed material was examined with the electron microscope. The myelin sheath itself is made up of spirally arranged lamellae in which the intraperiod and dense lines alternate. Inside the myelin sheath an inner cytoplasmic process surrounds the axon and where the external surfaces of its bounding membrane come together an internal mesaxon is formed. The intraperiod line begins within the mesaxon and the dense line usually begins in the same region by apposition of the cytoplasmic surfaces of the membrane. The width of each lamella is 140 A. The outer line in the sheath is the dense line and this terminates in a tongue where the cytoplasmic surfaces of the myelin-forming glial cell separate. Thus, central myelin in Xenopus tadpoles is arranged in the same way as peripheral myelin, the only difference being that in central fibres, cytoplasm on the outside of the sheath is confined to that present in the tongue. For this reason adjacent central sheaths come into apposition without any intervening material being present. When this occurs an intraperiod line is formed between them.

Triple Fixation For Electron Microscopy

1968 ◽  
Vol 26 ◽  
pp. 90-91 ◽  
Author(s):  
M. A. Hayat
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Electron Beam ◽  
Plasma Membrane ◽  
Myelin Sheath ◽  
Good Deal ◽  
Granular Structure ◽  
Oxidizing Agent ◽  
Fixation Technique ◽  
Large Clusters

Potassium permanganate has been successfully employed to study membranous structures such as endoplasmic reticulum, Golgi, plastids, plasma membrane and myelin sheath. Since KMnO4 is a strong oxidizing agent, deposition of manganese or its oxides account for some of the observed contrast in the lipoprotein membranes, but a good deal of it is due to the removal of background proteins either by dehydration agents or by volatalization under the electron beam. Tissues fixed with KMnO4 exhibit somewhat granular structure because of the deposition of large clusters of stain molecules. The gross arrangement of membranes can also be modified. Since the aim of a good fixation technique is to preserve satisfactorily the cell as a whole and not the best preservation of only a small part of it, a combination of a mixture of glutaraldehyde and acrolein to obtain general preservation and KMnO4 to enhance contrast was employed to fix plant embryos, green algae and fungi.

scholarly journals The Current Challenges for Drug Discovery in CNS Remyelination

2021 ◽  
Vol 22 (6) ◽  
pp. 2891
Author(s):  
Sonia Balestri ◽  
Alice Del Giovane ◽  
Carola Sposato ◽  
Marta Ferrarelli ◽  
Antonella Ragnini-Wilson
Keyword(s):  
Drug Screening ◽  
Myelin Sheath ◽  
Time Window ◽  
In Vitro Models ◽  
Adult Brain ◽  
Pharmacological Intervention ◽  
Cellular Models ◽  
New Findings ◽  
Myelin Injury

The myelin sheath wraps around axons, allowing saltatory currents to be transmitted along neurons. Several genetic, viral, or environmental factors can damage the central nervous system (CNS) myelin sheath during life. Unless the myelin sheath is repaired, these insults will lead to neurodegeneration. Remyelination occurs spontaneously upon myelin injury in healthy individuals but can fail in several demyelination pathologies or as a consequence of aging. Thus, pharmacological intervention that promotes CNS remyelination could have a major impact on patient’s lives by delaying or even preventing neurodegeneration. Drugs promoting CNS remyelination in animal models have been identified recently, mostly as a result of repurposing phenotypical screening campaigns that used novel oligodendrocyte cellular models. Although none of these have as yet arrived in the clinic, promising candidates are on the way. Many questions remain. Among the most relevant is the question if there is a time window when remyelination drugs should be administrated and why adult remyelination fails in many neurodegenerative pathologies. Moreover, a significant challenge in the field is how to reconstitute the oligodendrocyte/axon interaction environment representative of healthy as well as disease microenvironments in drug screening campaigns, so that drugs can be screened in the most appropriate disease-relevant conditions. Here we will provide an overview of how the field of in vitro models developed over recent years and recent biological findings about how oligodendrocytes mature after reactivation of their staminal niche. These data have posed novel questions and opened new views about how the adult brain is repaired after myelin injury and we will discuss how these new findings might change future drug screening campaigns for CNS regenerative drugs.

Adolescents and Inhalant Abuse: How Huffing Affects the Myelin Sheath

2012 ◽  
Vol 23 (2) ◽  
pp. 129-131 ◽  
Author(s):  
Carolyn A. Baird ◽  
Maxim W. Furek
Keyword(s):  
Myelin Sheath ◽  
Inhalant Abuse
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