Journal of Neuroscience, Vol 8, 1239-1244, Copyright © 1988 by Society for Neuroscience
Can oligodendrocytes attached to myelin proliferate?
SK Ludwin and DA Bakker
Department of Pathology (Neuropathology), Queen's University, Kingston, Ontario, Canada.
The uptake of thymidine by oligodendrocytes in the brains of adult mice was
examined after the induction of cortical traumatic lesions in an attempt to
determine whether mature oligodendrocytes actively attached to myelin
sheaths were capable of proliferating. In view of the great difficulty in
visualizing the connection between a given oligodendrocyte and a myelin
sheath even in the normal adult animal, the neuropil was made edematous in
the traumatized animals in order to separate out the components and to
study the oligodendrocyte processes. Uptake of tritiated thymidine was
found in oligodendrocytes, as well as in endothelial cells, astrocytes, and
microglia. The percentage of labeled oligodendrocytes appeared low in
relation to the total number of the oligodendrocytes. In addition, in a few
labeled cells, cytoplasmic processes could be seen extending to and
apparently forming the myelin sheath. The possibility that a differentiated
cell still attached to myelin may at the same time be able to proliferate
is of great significance in understanding the potential for remyelination
and recovery, in the adult, because it would imply that any oligodendrocyte
is a candidate for proliferation, rather than only uncommitted or immature
glial cells, which may be limited in the mature brain.