Figure 3.

(A and B) Immunofluorescent co-localization of SIX2 (green) and NCAM (red) in two distinct “zones of differentiation” within an FH WT specimen. The loosely aggregated and most undifferentiated blastema stains positively for both SIX2 and NCAM, although this region also contains more rare SIX2⁺/NCAM⁻ cells. As cells move toward the more differentiated epithelial state (SIX2⁻/NCAM⁻/DAPI⁺; blue only) showing tubule formation, the intermediate group of aggregating cells is SIX2⁻/NCAM⁺ (red only). Although not absolute, the majority of differentiating or differentiated WT cells appear to lose SIX2 expression, as shown in these two images (400 ×).