Non-somitic expression of uncx4.1. Whole-mount in situ hybridization of uncx4.1 at (A) tailbud stage, (B–D) 18 hours post fertilization (hpf), (E, F) 24 hpf, (G–L) 34 hpf, and (M) 48 hpf. (A, C, F, H, J) Dorsal view, (B, E, G, H, K–M) lateral view, and (D, I) frontal view. (A, C) Anterior to top, (B, E–H, J–M) to left, and (D, I) toward viewer. (A) Early expression in rhombomeres 3–5 (r3, r5) as shown by double in situ labeling with egr2b riboprobe. Expression in telencephalon (Te), olfactory placodes (OP), hypothalamus (Hy), and prospective hindbrain (HB) at (B–D) 18 hpf and (E, F) 24 hpf. Di = diencephalon, HB = hindbrain, Hy = hypothalamus, OP = olfactory placode, Te = telencephalon. (G, H) Expression extends to thalamus at 34 hpf. Ce = cerebellum, Ey = eye, Th = thalamus. (I) Transversal section showing expression in neuronal progenitor cells in the hindbrain at 34 hpf. (J) Arrowheads indicate expression in the hindbrain near exit roots of branchial motor neurons as shown by double in situ labeling with acetylated α-tubulin antibody at 34 hpf. Expression (K) in pharyngeal arches and (L) Corpuscle of Stannius at 34 hpf in lateral view. CS = Corpuscle of Stannius, PA = pharyngeal arches, YE = yolk extension. (M) Expression in central nervous system and (inset) Corpuscle of Stannius at 48 hpf. OT = optic tectum, Yo = yolk.