Fig. 6. tfap2a and tfap2b are co-expressed in the ectoderm, but only tfap2a is expressed in pharyngeal arch NCCs. Transverse cryosections through the pharyngeal region of embryos at 26 hpf (A-C) and 36 hpf (D-F) labeled by in situ hybridization with riboprobes to dlx2 (A,D), tfap2a (B,E) and tfap2b (C,F). Left side views, with the pharyngeal lumen, neural tube and notochord at the midline lying to the right. Arrowheads in D indicate unlabeled surface ectoderm. Scale bars: 50 µm.