Co-localization of the myelin-associated glycoprotein and the microfilament components, F-actin and spectrin, in Schwann cells of myelinated nerve fibres

1989 ◽  
Vol 18 (1) ◽  
pp. 47-60 ◽  
Author(s):  
Bruce D. Trapp ◽  
S. Brian Andrews ◽  
Albert Wong ◽  
Maureen O'Connell ◽  
John W. Griffin
Keyword(s):  
Schwann Cells ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
Myelin Associated Glycoprotein

The fine structure and morphological organization of non-myelinated nerve fibres

1956 ◽  
Vol 144 (917) ◽  
pp. 496-506 ◽  
Keyword(s):  
Fine Structure ◽  
Schwann Cell ◽  
Peripheral Nerve ◽  
Schwann Cells ◽  
Myelin Sheath ◽  
Peripheral Nerves ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
Morphological Organization ◽  
Myelinated Fibres

The fine structure and morphological organization of non-myelinated nerve fibres were studied by ultra-thin sectioning and electron microscopy in peripheral nerves, autonomic nerves and dorsal roots. Several non-myelinated fibres share the cytoplasm of a Schwann cell. The Schwann cells of non-myelinated fibres form a syncytium. The fibres are incompletely sur­rounded by Schwann cell cytoplasm and are suspended in the cytoplasm by mesaxons formed by the plasma membranes of the Schwann cell. The various relationships of mesaxon and nerve fibre are described. Non-myelinated fibres which do not share a Schwann cell are seen very frequently in the sciatic nerve of a new-born mouse but become less common as myelination proceeds and are rare in adults. It is therefore suggested that in developing peripheral nerves, the non­ myelinated fibres that are destined to myelinate are not organized into groups within a single Schwann cell, even before their myelin sheath has appeared; they are, at least for the ages examined here, individuals in relation to a surrounding individual Schwann cell. It is also suggested that the non-myelinated fibres that will never acquire a myelin sheath are organized in a developing peripheral nerve in the same manner as in the adult nerve—several fibres sharing a single Schwann cell that is part of a syncytial system of Schwann cells. Thus, in a developing peripheral nerve, it appears that two types of non-myelinated fibres are present—one destined to myelinate and lying alone in its own Schwann cell and the other, destined to remain unmyelinated and sharing, along with other non-myelinated fibres of the same type, a Schwann cell. The significance of these observations is discussed in relation to the development of nerve fibres and possible physiological importance.

Effect of the flavoid phloretin on Ca2+-activated K+ channels in myelinated nerve fibres of Xenopus laevis

1994 ◽  
Vol 165 (1-2) ◽  
pp. 167-170 ◽  
Author(s):  
Duk-Su Koh ◽  
Gordon Reid ◽  
Werner Vogel
Keyword(s):  
Xenopus Laevis ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
K Channels

Abnormal skin development in pupoid foetus (pf/pf) mutant mice

Development ◽  
1985 ◽  
Vol 87 (1) ◽  
pp. 47-64
Author(s):  
Chris Fisher ◽  
Edward J. Kollar
Keyword(s):  
Blood Vessels ◽  
Schwann Cells ◽  
Cell Population ◽  
Epidermal Cell ◽  
Basal Lamina ◽  
Mutant Mice ◽  
Nerve Fibres ◽  
Skin Development ◽  
Cell Layers

At 13 days of development the epidermis of mice homozygous for the pupoid foetus (pf/pf) mutation varies in thickness between one and ten cell layers. By 16 days of development cells from the dermis have invaded the epidermis and may be found throughout the epidermis and on its surface. Among these cells are nerve fibres and Schwann cells as well as other unidentified cells. Antibodies directed against fibronectin bind to these abnormal groups of cells in the mutant epidermis and on its surface. A basal lamina, as determined by ultrastructure and by the immuno-fluorescent localization of laminin, was always found at the interface of the mutant epidermis and the invading cell population. By 19 days of development the mutant epidermis is thickened and is permeated by a network of cells including nerve fibres, Schwann cells, blood vessels, and collagen and fibronectin-secreting cells. A basal lamina always separates these groups of invading cells from the epidermal cell population.

Modulated adhesion: a proposal for the role of myelin-associated glycoprotein in myelin wrapping.

1989 ◽  
Vol 35 (5) ◽  
pp. 717-720 ◽  
Author(s):  
J Attia ◽  
M Tropak ◽  
P W Johnson ◽  
W Newerly-Abranow ◽  
T Pawson ◽  
...  
Keyword(s):  
Structural Analysis ◽  
Schwann Cells ◽  
Clinical Findings ◽  
Membrane Glycoprotein ◽  
Nervous Systems ◽  
Phosphorylation State ◽  
Phosphatase Activities ◽  
Cell Assays ◽  
Myelin Associated Glycoprotein

Abstract Myelin-associated glycoprotein (MAG) is a 100-kDa integral membrane glycoprotein expressed by oligodendrocytes and Schwann cells in the central and peripheral nervous systems, respectively. It is found first in loosely wrapped myelin and then periaxonally after compaction. Clinical findings, structural analysis, and cell assays indicate a role for MAG in adhesion. We propose that the phosphorylation state of MAG modulates its adhesion and that a minimum spatial requirement for the separation of the kinase and phosphatase activities postulated by this model may explain the correlation between axon size and myelination state.

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