Journal of Neuroscience, Vol 11, 3146-3154, Copyright © 1991 by Society for Neuroscience
Neurofilament redistribution in transected nerves: evidence for bidirectional transport of neurofilaments
JD Glass and JW Griffin
Department of Neurology and Pathology (Neuropathology), Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Nerve fibers of the C57BL/6/Ola mouse exhibit very slow Wallerian
degeneration following axotomy, thus allowing prolonged observation of
mammalian axons separated from their cell bodies. The present study
utilized teased-fiber preparations, silver histochemistry,
immunocytochemistry, and electron microscopy to examine the distribution of
axonal components in the distal stumps of axotomized sciatic nerves in
C57BL/6/Ola mice. In examining nerve segments at varying intervals after
nerve transection, we found no evidence of proximal-to-distal "emptying
out" of the cytoskeleton, as would be predicted if the cytoskeleton in
these transected nerves were undergoing anterograde transport as an
assembled structure. Instead, we observed a gradual redistribution of
cytoskeletal constituents over time, dominated by the progressive
accumulation of neurofilaments at the severed ends of axons. In particular,
there were massive accumulations at the proximal ends of the distal stumps.
These results strongly suggest that, at least in transected nerve fibers,
neurofilaments can be transported bidirectionally.