Schematic timeline shows the experimental design. GFP+ cells found in the brain parenchyma, 21 days after infusion of vehicle (A) or EGF (B). In the corpus callosum (CC) many cells had characteristic of pre-myelinating and myelinating oligodendrocytes (C) that frequently formed cellular “cords” (D). Similar findings were observed in all regions at every time point. E - G: Confocal Z-stack 3D reconstructions of the GFP+ cells found in the corpus callosum. H - N: Markers expressed by RCAS-GFP-labeled cells found in the corpus callosum. These cells have a close relationship with neurofilaments (NF) (N). Sep: Septum, Str: Striatum, BV: Blood vessel. V: Ventricle. Scale bar in A-B = 100 μm; B, C, G - K = 20 μm; N = 5 μm.