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