Myelin was immunostained with monoclonal antibody 8-18C5, which recognizes myelin oligodendrocyte glycoprotein (MOG). Hybridoma cells were provided by Dr. Minetta Gardinier, University of Iowa (22) . MOG immunolabeling was detected with donkey antimouse IgG F(ab') 2 conjugated with Cy3 (Jackson Immunoresearch).