Figure 3. Characterization of Sox-2⁺ cells in the substantia nigra and striatum of naïve adult primates.

A. Confocal images show BrdU incorporation (yellow arrowhead), and co-expression of Ki67 (yellow arrowhead) in Sox-2⁺ cells in the parenchyma of the SNpc. Sox-2⁺ cells were never positive for TH. Some Sox-2⁺ cells corresponded to satellite glial cells sitting on TH⁺ neurons, as shown in the merged panels (blue arrowheads). Many Sox-2⁺ cells expressed GFAP (yellow arrowhead) but there were also Sox-2⁺/GFAP^– (blue arrowhead) that may correspond to amplifying progenitors. There was no Sox-2⁺/CR⁺ co-expression in any cell in this region. Scale bar = 20 µm. B. In the striatal parenchyma some Sox2⁺ cell showed BrdU incorporation (yellow arrowhead) and co-expressed Ki67 (yellow arrowhead). Most Sox-2⁺ striatal cells expressed GFAP (yellow arrowhead) but there were also Sox-2⁺/GFAP^– (blue arrowhead). Some CR⁺ striatal neurons showed nuclear expression of Sox-2 (yellow arrowhead) while others did not (blue arrowhead). Scale bars = 10 µm. Abbreviations: Substantia nigra pars compacta: SNpc; tyrosine hydroxylase: TH; glial fibrillary acidic protein: GFAP; calretinin: CR.