Fig. 4

Pax7 is a marker of the xanthophore lineage. In situ mRNA hybridisation for pax7 (A, B, E–L, S–Y), xdh (S–U′) and dct (V–Y) and immunodetection of Pax7 (C, D, M, N, Q, R) and sox10:GFP (O–R). Dorsal flat mounts (A–F, M–S, V) are anterior to top. Lateral flat mount (H) is anterior to left and dorsal to top. Transverse cryosections (G, I–L, T, U, W–Y) are dorsal to top. (A–D) Pax7 mRNA is detected at 18 s in NC-like cells at the mid-hindbrain boundary (A, B; arrowheads), concomitant with Pax7 protein in cranial NC-like cells (C, D; brown, arrowheads). (E–L) By 25 hpf, pax7 mRNA is detected in pre-migratory (arrows) and laterally migrating (arrowheads) NC-like cells in head (E–G), trunk (H, shown in section I and magnified J, K) and tail (L) regions. (M–R) Co-localisation of GFP from the sox10:egfp transgenic line with Pax7 protein demonstrates that Pax7 marks NC cells (arrowheads). (S–Y) Co-localisation in NC of pax7 (white arrowheads) and xdh but not dct (black arrowheads) mRNAs demonstrates that pax7 is expressed in the xanthophore lineage. Cryosections at the level of the forebrain (T, W) or hindbrain (U, X, Y), with the boxes in panels T, U, W and panel X magnified in panels T′, U′, W′ and panel X inset, respectively.