Journal of Neuroscience, Vol 16, 2635-2641, Copyright © 1996 by Society for Neuroscience
Expanded CNS myelin sheaths formed in situ in the presence of an IgM antigalactocerebroside-producing hybridoma
J Rosenbluth, WL Liang, Z Liu, D Guo and R Schiff
Department of Physiology and Neuroscience and Institute of Rehabilitation Medicine, New York University School of Medicine, New York 10016, USA.
When O1 hybridoma cells, which produce an IgM antigalacto-cerebroside, are
implanted into the dorsal columns of 4-8 d rat spinal cord, some of the
myelin that subsequently develops in the immediate vicinity displays an
abnormal periodicity. The spacings that are seen cluster at approximately
19 nm and 31 nm, roughly two and three times the normal 11 nm spacing. In
the expanded sheaths, major dense lines are separated by broad
extracellular spaces containing a dense material in which single or double
rows of approximately 10 nm circular profiles can be identified, consistent
with the "central rings" of IgM molecules. Because IgM is multivalent, it
may serve to link adjacent lamellae together in place of intrinsic myelin
molecules that normally interact at close range. Extensive direct contact
between myelin components of successive myelin lamellae is thus not
essential to signal the growth of the oligodendrocyte membrane or the
spiral wrapping of that membrane around axons during myelinogenesis, or to
stabilize the myelin spiral that forms.