Fig. 3. Lineage tracing of Phox2b-expressing cells. Lineage tracing was performed by crossing R26R mice with either Pdx1-cre (A,B) or Wnt1-cre (C-E) mouse lines. Mouse embryos harvested at E12.5 were stained for β-galactosidase activity with X-gal (blue), and stained for Pdx1 (A,C) or Phox2b (B,D,E) by immunohistochemistry with peroxidase labeling (brown). Scale bars: 50 µm.