Expression of D-V arch patterning genes. (A-C) Morphogenesis of arches 1 (mandibular) and 2 (hyoid) in the zebrafish embryo. Lateral brightfield views of live embryos. By 36 hours postfertilization (hpf) the arch is patterned into distinct ventral (pink), intermediate (cyan), and dorsal (yellow) domains. These later give rise to lower jaw, joint and upper jaw elements, respectively. aa: anguloarticular, d: dentary, hm: hyomandibular, iop: interopercle, mx: maxilla, op: opercle, pm: premaxilla, pop: preopercle, sop: subopercle, sy: symplectic. (D) NanoString measurements of D-V patterning gene expression in zebrafish arches, normalized to per-cell levels and displayed as heat maps. n ≥ 3 biological replicates/time point. Expression of the intermediate factor dlx3b is highest at 20 hpf before other factors. (E-T) HCR in situ gene expression analysis. DAPI (blue) marks nuclei and dlx2a (white) marks neural crest. dlx3b (left column) and dlx5a (right column) expression are in red, and the ventral domain gene hand2 is in green. dlx3b expression is first detected strongly at 17 hpf, while dlx5a expression appears at 18 hpf. hand2 expression in the first arch is first detected at 20 hpf.