IUBio

extracellular matrix in CNS

G K GRAY gord at homostudy.win-uk.net
Fri Dec 27 19:51:34 EST 1996


 
In article <01bbf2f5$83a72820$7ef90398 at jkern.duke.edu>, "Jason C. Doss" (jkdoss at acpub.duke.edu) writes:
>
>
>> What kind of extracellular matrix (if any) occurs into the central
>> nervous system?
>
>To my knowledge, the only extracellular matrix occurs at the basement
>membranes surrounding capillaries, constituting one component of the
>blood-brain barrier.  This basement membrane is of similar, if not the
>same, constitution as capillary basement membrane elsewhere in the body. 
>White matter contains another substance, myelin, which is responsible for
>insulating the axons of neurons in the spinal cord and beneath the cortex,
>as well as in the peripheral nervous system.  Myelin, however, is
>INTRAcellular, contained within oligodendrocytes in the CNS, and Schwann
>cells within the peripheral nervous system.  Please correct me if I'm
>wrong, but I don't think I am.
>
>Hope this helps,
>JCD

Generally correct but slightly off the mark on myelin structure: -
It is an extension of the cell-membrane of both Oligodendrocytes 
and of one type of Schwann Cell. In both cases the extension winds
around the axon like a finger of a rubber glove being wrapped
around a pencil.  Its representation as the "insulation" on an axon
"cable" is being seriously called into question by a number of
biophysicists in spite of the way it is presented in textbooks. 

Cheers!  Gord




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