The localization of sodium and calcium to Schwann cell paranodal loops at nodes of Ranvier and of calcium to compact myelin

1980 ◽  
Vol 9 (2) ◽  
pp. 185-205 ◽  
Author(s):  
Mark H. Ellisman ◽  
Peter L. Friedman ◽  
W. J. Hamilton
Keyword(s):  
Schwann Cell ◽  
Nodes Of Ranvier

scholarly journals Immunoelectron microscopic localization of neural cell adhesion molecules (L1, N-CAM, and MAG) and their shared carbohydrate epitope and myelin basic protein in developing sciatic nerve.

1986 ◽  
Vol 103 (6) ◽  
pp. 2439-2448 ◽  
Author(s):  
R Martini ◽  
M Schachner
Keyword(s):  
Cell Adhesion ◽  
Schwann Cell ◽  
Adhesion Molecules ◽  
Schwann Cells ◽  
Cell Adhesion Molecules ◽  
Basic Protein ◽  
Staining Pattern ◽  
Nodes Of Ranvier ◽  
Carbohydrate Epitope ◽  
Neural Cell Adhesion

The cellular and subcellular localization of the neural cell adhesion molecules L1, N-CAM, and myelin-associated glycoprotein (MAG), their shared carbohydrate epitope L2/HNK-1, and the myelin basic protein (MBP) were studied by pre- and post-embedding immunoelectron microscopic labeling procedures in developing mouse sciatic nerve. L1 and N-CAM showed a similar staining pattern. Both were localized on small, non-myelinated, fasciculating axons and axons ensheathed by non-myelinating Schwann cells. Schwann cells were also positive for L1 and N-CAM in their non-myelinating state and at the onset of myelination, when the Schwann cell processes had turned approximately 1.5 loops. Thereafter, neither axon nor Schwann cell could be detected to express the L1 antigen, whereas N-CAM was found in the periaxonal area and, more weakly, in compact myelin of myelinated fibers. Compact myelin, Schmidt-Lanterman incisures, paranodal loops, and finger-like processes of Schwann cells at nodes of Ranvier were L1-negative. At the nodes of Ranvier, the axolemma was also always L1- and N-CAM-negative. The L2/HNK-1 carbohydrate epitope coincided in its cellular and subcellular localization most closely to that observed for L1. MAG appeared on Schwann cells at the time L1 expression ceased. MAG was then expressed at sites of axon-myelinating Schwann cell apposition and non-compacted loops of developing myelin. When compaction of myelin occurred, MAG remained present only at the axon-Schwann cell interface; Schmidt-Lanterman incisures, inner and outer mesaxons, and paranodal loops, but not at finger-like processes of Schwann cells at nodes of Ranvier or compacted myelin. All three adhesion molecules and the L2/HNK-1 epitope could be detected in a non-uniform staining pattern in basement membrane of Schwann cells and collagen fibrils of the endoneurium. MBP was detectable in compacted myelin, but not in Schmidt-Lanterman incisures, inner and outer mesaxon, paranodal loops, and finger-like processes at nodes of Ranvier, nor in the periaxonal regions of myelinated fibers, thus showing a complementary distribution to MAG. These studies show that axon-Schwann cell interactions are characterized by the sequential appearance of cell adhesion molecules and MBP apparently coordinated in time and space. From this sequence it may be deduced that L1 and N-CAM are involved in fasciculation, initial axon-Schwann cell interaction, and onset of myelination, with MAG to follow and MBP to appear only in compacted myelin. In contrast to L1, N-CAM may be further involved in the maintenance of compact myelin and axon-myelin apposition of larger diameter axons.

scholarly journals Gliomedin Mediates Schwann Cell-Axon Interaction and the Molecular Assembly of the Nodes of Ranvier

Neuron ◽  
2005 ◽  
Vol 47 (2) ◽  
pp. 215-229 ◽  
Author(s):  
Yael Eshed ◽  
Konstantin Feinberg ◽  
Sebastian Poliak ◽  
Helena Sabanay ◽  
Offra Sarig-Nadir ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Molecular Assembly ◽  
Nodes Of Ranvier ◽  
Cell Axon

scholarly journals Myelination of peripheral nerves is controlled by PI4KB through regulation of Schwann cell Golgi function

2020 ◽  
Vol 117 (45) ◽  
pp. 28102-28113 ◽  
Author(s):  
Takashi Baba ◽  
Alejandro Alvarez-Prats ◽  
Yeun Ju Kim ◽  
Daniel Abebe ◽  
Steve Wilson ◽  
...  
Keyword(s):  
Schwann Cell ◽  
Peripheral Nerves ◽  
Large Diameter ◽  
Small Diameter ◽  
Nerve Fibers ◽  
Protein Glycosylation ◽  
Mutant Mice ◽  
Nodes Of Ranvier ◽  
Golgi Compartment ◽  
Sciatic Nerves

Better understanding myelination of peripheral nerves would benefit patients affected by peripheral neuropathies, including Charcot–Marie–Tooth disease. Little is known about the role the Golgi compartment plays in Schwann cell (SC) functions. Here, we studied the role of Golgi in myelination of peripheral nerves in mice through SC-specific genetic inactivation of phosphatidylinositol 4-kinase beta (PI4KB), a Golgi-associated lipid kinase. Sciatic nerves of such mice showed thinner myelin of large diameter axons and gross aberrations in myelin organization affecting the nodes of Ranvier, the Schmidt–Lanterman incisures, and Cajal bands. Nonmyelinating SCs showed a striking inability to engulf small diameter nerve fibers. SCs of mutant mice showed a distorted Golgi morphology and disappearance of OSBP at the cis-Golgi compartment, together with a complete loss of GOLPH3 from the entire Golgi. Accordingly, the cholesterol and sphingomyelin contents of sciatic nerves were greatly reduced and so was the number of caveolae observed in SCs. Although the conduction velocity of sciatic nerves of mutant mice showed an 80% decrease, the mice displayed only subtle impairment in their motor functions. Our analysis revealed that Golgi functions supported by PI4KB are critically important for proper myelination through control of lipid metabolism, protein glycosylation, and organization of microvilli in the nodes of Ranvier of peripheral nerves.

Membrane Specializations in Developing Nodes of Ranvier

1980 ◽  
Vol 38 ◽  
pp. 626-627
Author(s):  
J.H. Tao-Cheng ◽  
J. Rosenbluth
Keyword(s):  
Schwann Cell ◽  
Freeze Fracture ◽  
Structural Features ◽  
Nerve Fibers ◽  
Nodes Of Ranvier ◽  
Myelinated Nerve ◽  
Thin Sections ◽  
Frog Tadpole ◽  
Cell Layers ◽  
Mature Node

Mature myelinated nerve fibers exhibit distinctive structural features at nodes of Ranvier and the adjacent paranodal regions. In order to obtain information about the interrelationships between these specializations during development, thin sections and freeze-fracture replicas of immature peripheral nerve fibers from grass frog tadpole hind legs were examined during the period of myelinogenesis. Early in myelination axons are enwrapped individually by a few loose Schwann cell layers whose edges overhang each other forming "terminal loops" against the axolemma. Unlike those of the mature node, these loops are widely sepa-rated and irregularly spaced (Fig.l), and similarly the presumptive nodal region between successive developing myelin segments is usually much longer than adult nodes of Ranvier. The presumptive nodal axolemma may exhibit a cytoplasmic "undercoating." However, the density of this coating is highly variable. Usually it is much lower than at adult nodes, and in some cases the undercoating is not distinguishable. The outermost layers of the Schwann cell are usually the first to form axoglial junctional specializations character¬ized by the presence of "transverse bands" and ER cisternae applied to the junctional Schwann cell membrane. In some instances the outermost layer con¬tacts the axon over an extensive area and forms multiple small junctional specializations at widely separated intervals along the length of the axolemma.

Sign in / Sign up

Export Citation Format

Share Document