RT Journal Article SR Electronic T1 Defective oligodendrocyte development and severe hypomyelination in PDGF-A knockout mice JF Development JO Development FD The Company of Biologists Limited SP 457 OP 467 VO 126 IS 3 A1 Fruttiger, M. A1 Karlsson, L. A1 Hall, A.C. A1 Abramsson, A. A1 Calver, A.R. A1 Bostrom, H. A1 Willetts, K. A1 Bertold, C.H. A1 Heath, J.K. A1 Betsholtz, C. A1 Richardson, W.D. YR 1999 UL http://dev.biologists.org/content/126/3/457.abstract AB There is a class of oligodendrocyte progenitors, called O-2A progenitors, that is characterized by expression of platelet-derived growth factor α-receptors (PDGFR(α)). It is not known whether all oligodendrocytes are derived from these PDGFRalpha-progenitors or whether a subset(s) of oligodendrocytes develops from a different, PDGFR alpha-negative lineage(s). We investigated the relationship between PDGF and oligodendrogenesis by examining mice that lack either PDGF-A or PDGF-B. PDGF-A null mice had many fewer PDGFR alpha-progenitors than either wild-type or PDGF-B null mice, demonstrating that proliferation of these cells relies heavily (though not exclusively) on PDGF-AA homodimers. PDGF-A-deficient mice also had reduced numbers of oligodendrocytes and a dysmyelinating phenotype (tremor). Not all parts of the central nervous system (CNS) were equally affected in the knockout. For example, there were profound reductions in the numbers of PDGFR alpha-progenitors and oligodendrocytes in the spinal cord and cerebellum, but less severe reductions of both cell types in the medulla. This correlation suggests a close link between PDGFRalpha-progenitors and oligodendrogenesis in most or all parts of the CNS. We also provide evidence that myelin proteolipid protein (PLP/DM-20)-positive cells in the late embryonic brainstem are non-dividing cells, presumably immature oligodendrocytes, and not proliferating precursors.