scholarly journals The myelin-associated glycoprotein is enriched in multivesicular bodies and periaxonal membranes of actively myelinating oligodendrocytes.

1989 ◽  
Vol 109 (5) ◽  
pp. 2417-2426 ◽  
Author(s):  
B D Trapp ◽  
S B Andrews ◽  
C Cootauco ◽  
R Quarles
Keyword(s):  
Nervous System ◽  
Multivesicular Bodies ◽  
Immunoglobulin Gene ◽  
Developmentally Regulated ◽  
Adult Rat ◽  
Pns Myelin ◽  
The Central Nervous System ◽  
Immunoglobulin Gene Superfamily ◽  
Myelin Associated Glycoprotein ◽  
Rat Cns

The myelin-associated glycoprotein (MAG) is a member of the immunoglobulin gene superfamily that is selectively expressed by myelin-forming cells. A developmentally regulated, alternative splicing of a single MAG transcript produces two MAG polypeptides (72 and 67 kD) in the central nervous system (CNS). MAG occurs predominantly as the 67-kD polypeptide in the peripheral nervous system (PNS). This study determined the subcellular localization of CNS MAG at different postnatal times when the 72-kD form (7-d) and 67-kD form (adult) are quantitatively abundant. These distributions were also compared to those of MAG in the PNS. In adult rat, MAG is selectively enriched in periaxonal membranes of CNS myelin internodes. This restricted distribution differs from that in PNS myelin internodes where MAG is also enriched in paranodal loops, Schmidt-Lanterman incisures, and mesaxon membranes. In 7-d-old rat CNS, MAG was associated with periaxonal membranes during axonal ensheathment and enriched in Golgi membranes and cytoplasmic organelles having the appearance of multivesicular bodies (MVBs). MAG-enriched MVBs were found in oligodendrocyte perinuclear regions, in processes extending to myelin internodes, and along the myelin internode in outer tongue processes and paranodal loops. MAG-enriched MVBs were not found in oligodendrocytes from adult animals or in myelinating Schwann cells. These findings raise the possibility that the 72-kD MAG polypeptide is associated with receptor-mediated endocytosis of components from the periaxonal space or axolemma during active stages of myelination.

Schwannosis in Three Foals and a Calf

2019 ◽  
Vol 56 (5) ◽  
pp. 783-788 ◽  
Author(s):  
Ileana C. Miranda ◽  
Kyle R. Taylor ◽  
William Castleman ◽  
Alexander de Lahunta ◽  
Brian A. Summers ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Schwann Cells ◽  
Mass Effect ◽  
Neurofibromatosis Type ◽  
Proliferating Cells ◽  
Pns Myelin ◽  
The Central Nervous System ◽  
Protein Zero

Proliferation of ectopic Schwann cells within the central nervous system (CNS) parenchyma (schwannosis) in early life is most commonly associated with human neurofibromatosis type-2 and has been unrecognized in domestic animals. Three foals and a calf, 5 to 11 weeks old, with progressive neurological signs from birth were studied. Histologically, at multiple levels of the spinal cord, all animals had bilateral plaques of proliferative spindle cells, predominantly affecting the white matter adjacent to dorsal and ventral nerve roots and variably extending into the gray matter. Proliferating cells had strong intracytoplasmic immunoreactivity for the Schwann cell markers myelin protein zero and periaxin, highlighting the formation of peripheral nervous system (PNS) myelin within the spinal cord. In all cases, foci of disorganized neural tissue (glioneuronal hamartomas) were present, which in 2 cases formed a mass effect that resulted in syringohydromyelia. Neonatal presentation suggests a congenital maldevelopment of the nervous system, with spontaneous invasion of PNS-derived Schwann cells into the CNS.

scholarly journals Presence of the myelin-associated glycoprotein correlates with alterations in the periodicity of peripheral myelin.

1982 ◽  
Vol 92 (3) ◽  
pp. 877-882 ◽  
Author(s):  
B D Trapp ◽  
R H Quarles
Keyword(s):  
Schwann Cell ◽  
Peripheral Nerves ◽  
Minor Component ◽  
Integral Membrane Protein ◽  
Structural Protein ◽  
Adult Rat ◽  
Pns Myelin ◽  
Myelin Associated Glycoprotein ◽  
A Minor ◽  
Periaxonal Space

The myelin-associated glycoprotein (MAG) is an integral membrane protein (congruent to 100,000 mol wt) which is a minor component of purified peripheral nervus system (PNS) myelin. In the present study, MAG was localized immunocytochemically in 1-micrometer thick Epon sections of 7-d and adult rat peripheral nerves, and its localization was compared to that of the major structural protein (Po) of PNS myelin. To determine more precisely the localization of MAG, immunostained areas in 1 micrometer sections were traced on electron micrographs of identical areas from adjacently cut thin sections.l MAG was localized in periaxonal membranes. Schmidt-Lantermann incisures, paranodal membranes, and the outer mesaxon of PNS myelin sheaths. Compact regions of PNS myelin did not react with MAG antiserum. The results demonstrate MAG's presence in "'semi-compact" Schwann cell or myelin membranes that have a gap of 12-14 nm between extracellular leaflets and a spacing of 5 nm or more between cytoplasmic leaflets. In compact regions of the myelin sheath which do not contain MAG, the cytoplasmic leaflets are "fused" and form the major dense line, whereas the extracellular leaflets are separated by a 2.0 nm gap appearing as paired minor dense lines. Thus, it is proposed that MAG plays a role in maintaining the periaxonal space, Schmidt-Lantermann incisures, paranodal myelin loops, and outer mesaxon by preventing "complete" compaction of Schwann cell and myelin membranes. The presence of MAG in these locations also suggests that MAG may serve a function in regulating myelination in the PNS.

Immunohistochemical localization of the voltage-gated potassium channel subunit Kv1.4 in the central nervous system of the adult rat

2003 ◽  
Vol 26 (3) ◽  
pp. 209-224 ◽  
Author(s):  
Rafael Luján ◽  
Carlos de Cabo de la Vega ◽  
Eduardo Dominguez del Toro ◽  
Juan J Ballesta ◽  
Manuel Criado ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Potassium Channel ◽  
Immunohistochemical Localization ◽  
Voltage Gated ◽  
Adult Rat ◽  
The Central Nervous System

scholarly journals Expression of Neuronal Kinesin Heavy Chain Is Developmentally Regulated in the Central Nervous System of the Rat

2002 ◽  
Vol 69 (5) ◽  
pp. 1840-1849 ◽  
Author(s):  
G. Vignali ◽  
C. Lizier ◽  
M. T. Sprocati ◽  
C. Sirtori ◽  
G. Battaglia ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Heavy Chain ◽  
Developmentally Regulated ◽  
Kinesin Heavy Chain ◽  
The Central Nervous System
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