Single or multiple oligodendroglial lineages: A controversy

The text books all say oligodendrocytes are the last cell to arise during d evelopment. The analysis of the spatio-temporal pattern of expression of pl p/dm-20 during embryonic development in both the chick and the mouse provid es evidence that the induction of oligodendrocyte occurs much earlier than we thought. In fact, it seems as though these cells must arise nearly simul taneously with neurons and it is just that they do not mature until later. Furthermore, we review the experimental arguments in favor of the existence of at least two, if not more, oligodendrocyte precursor cells: one is defi ned by the expression of PDGFR alpha, another characterized by expression o f plp/dm-20 is independent from PDGF-AA for its proliferation and survival. We then postulate the existence of a third family of yet unknown origin. G LIA 29:143-148, 2000. (C) 2000 Wiley-Liss, Inc.