Double-label immunofluorescence of S100α and ATP5B in a normal control DRG and a DRG of an FA patient. (a)-(c) normal control; (d)-(f) FA; (a) and (d) S100α (Alexa488, green); (b) and (e) ATP5B (Cy3, red); (c) and (f) merged images. S100α immunofluorescence is a robust marker of normal satellite cells (a) and hyperplastic satellite cells in FA (d). In the normal DRG, ATP5B fluorescence is prominent in neuronal cytoplasm (b), and only sparse reaction product is present in the tissue between neurons. In contrast, satellite cells in FA (e) show a great abundance of granular ATP5B immunofluorescence. The arrows in (d)-(f) indicate a residual nodule. Bars, 20 μm.