Stem cells implanted into the brains of unlesioned animals. (a) Implanted eNCSCs (top row) and BMSCs (bottom row) after IO-TAT-FITC labeling and stereotactic implantation (arrows) onto the corpus callosum remained visible by MRI in the same animals for at least 30 days. The spread of the cells appeared to be equally distributed both laterally and medially from the injection site, suggesting no inherent preference of the cells to migrate in one particular direction in the unlesioned brain. False-colored inserts allow better visualization of the hypointense regions. Implanted eNCSCs after IO-TAT-FITC labeling and stereotactic implantation onto the corpus callosum were visible by postmortem histology for a minimum of 30 days. (b) Implanted NCSCs (green) on the corpus callosum demonstrated some GFAP (red) glial differentiation (arrows). Nuclear stain DAPI (blue). (c) Implanted NCSCs migrate laterally along the white-matter tract of the corpus callosum for approximately 450 μm. (d) Implanted NCSCs (green) did not become S-100+ (a marker of mature Schwann cells). Insert shows mature S-100+ Schwann cells in a section of peripheral nerve, immunostained under identical conditions as a positive control. Scale bars: 20 μm (b, d), and 100 μm (c).