Mouse oligodendrocyte lineage cells in culture. (A) OPCs purified via immunopanning for PDGFRa and cultured in the presence of PDGF. (B) Differentiating oligodendrocytes 48 h following removal of PDGF and addition of T3. Cells have dramatically changed their morphology, and they all express CNP and are in the process of up-regulating MBP. NG2, NG2 chondroitin sulfate proteoglycan; CNP, 2',3'-cyclic-nucleotide 3'-phosphodiesterase; MBP, myelin basic protein. Scale bars, 10 µm.