Fig 2: Double immunofluorescence staining in a representative case of canine non-suppurative meningoencephalitis of unknown etiology (dog number 18).Co-expression of p75NTR (red, A) and Sox2 (green, A) is observed in bipolar cells (arrow), morphologically resembling Schwann cells, which are localized in close proximity to a blood vessel. Note that few p75NTR-expressing cells lack Sox2 expression (arrowhead). In contrast to Sox2, GAP-43 (green, B), GFAP (green, C), Egr2/Krox20 (green, D), periaxin (green, E), and PDGFR-a (green, arrowhead, F) are not co-expressed with p75NTR (red), thus implying that p75NTR/Sox2-positive cells might represent a dedifferentiated Schwann cell phenotype within the injured CNS. Nuclear counterstaining (blue) with bisbenzimide. (A), (B) and (C) scale bars: 100 µm. (D), (E) and (F) scale bars: 50 µm.

Fig 3: a–j Images of SCSCs maintained for 6 days in vitro after culture preparation and immediate application of NCSCs. Images of unsectioned cultures and neurospheres after light and confocal microscopy (a–c): black arrowheads in image of light microscopy (a) show neurospheres of NCSCs with no signs of migration. Confocal laser scanning images (b) and (c) show NCSCs marked with eGFP (green) and NeuN (DyLight-549, red) after immunohistochemistry. NCSCs migrated on top of SCSCs (c) but remained in spheres when there was no contact with the cultures (b). Images of longitudinal sections through SCSCs and NCSCs (e, f, g, h). Diagram (d) shows how the cultures were sectioned longitudinally. NCSCs were applied on SCSCs directly after culture preparation in order to avoid scar formation that occurs on top of the cultures and maintained for 6 days in vitro. Images (g) and (h) represent parts of (e) and (f) in a higher magnification indicated by dashed lines. The majority of NCSCs migrated on the surface of the culture and some NCSC appeared to migrate through the culture (white arrows). The spheres stained against GFAP showed signs of GFAP immunoreactivity in the edges (white arrowheads in h) but no signs of co-localization between GFAP and eGFP autofluorescence were observed, suggesting astrocytic migration from SCSCs through the neurospheres. Staining of longitudinal sections against SOX2 and Krox20 (i, j). Few cells showed colocalization with SOX2 (small arrows in i) and Krox20 (large arrows in j), markers of undifferentiated neural crest stem cells. The small boxes in the upper right-hand corner of (i) and (j) represent areas of co-localization between eGFP and SOX2 or Krox20, respectively, in higher magnification