Journal of Neuroscience, Vol 6, 3731-3738, Copyright © 1986 by Society for Neuroscience
Migration and myelination by adult glial cells: reconstructive analysis of tissue culture experiments
MK Wolf, MC Brandenberg and S Billings-Gagliardi
Adult glia are capable of at least limited myelination of CNS axons.
However, it is difficult to quantitate their myelination or migratory
capacities and to examine contributions of the CNS environment or exogenous
factors that might promote or inhibit this process in situ. We have
therefore developed a mouse tissue culture system in which optic nerve glia
(in the form of appropriately handled optic nerve) are added to chemically
demyelinated cerebellar axons. Optic nerve up to postnatal day 411 (P411)
contains cells that can migrate out of the nerve into the cerebellar
explant and form myelin around its axons. The success rate for myelin
formation in these cultures is 57% for immature (P7-11) glia and 55% for
adult (P50-411) glia. Computer-generated reconstructions of cultures
containing immature (P8) and adult (P89 and P139) nerves demonstrate that
in all 3 cases the glia may migrate more than 0.6 mm before myelinating
axons, assuming the shortest possible track. Both the age limit for
myelination and distance limit for migration, if any, remain to be
determined for these adult glia. In successful cultures, myelin always
directly abuts the optic nerve surface, whether or not it also extends
further, suggesting that migrating glia may depend upon contact guidance by
myelin-receptive axons. We conclude that this culture system is a useful
model of adult CNS myelin regeneration, in which one can examine the
influence of potential trophic or toxic factors on specific aspects of
myelinating glial cell behavior.