Migratory cranial neural crest cell populations medial to the eye are reduced in MO-injected embryos. (A-D) Live sox10:EGFP transgenic embryos imaged at 14 hpf (A, C) and 16 hpf (B, D). (A-E) Lateral views: anterior is towards the left dorsal is upwards. (A and B) Uninjected embryos (n = 6) showed migration of GFP-positive neural crest cells medial to the eye (m) starting at 14 hpf. By 16 hpf (B), cells migrated anteriorly and ventrally. (C and D) hdac4 MO-injected embryos (n = 6) showed a reduction of GFP-positive cells medial to the eye (m). (E) Measurement of the maximum length of the migratory trajectories of GFP-postive cells medial and dorsal to the eye (blue line and red line, respectively). Measurements were made on fixed uninjected and MO-injected sox10:EGFP transgenic embryos at 14 hpf (uninjected n = 23, injected n = 15) and 16 hpf (uninjected n = 17, injected n = 19). (G) The absolute distance from the posterior region of the eye to the frontier of GFP-positive cells medial to the eye in MO-injected fish was significantly shorter than in uninjected controls at both 14 and 16 hpf (p < 0.001). (H) The absolute distance to the frontier of GFP-positive cells dorsal to the eye was significantly longer in uninjected controls compared to the distance in MO-injected fish at 14 hpf (p < 0.001), but not at 16 hpf. (I) The relative percentage difference of medial vs. dorsal cell migration was not significant between MO-injected embryos and uninjected controls at 14 hpf, but becomes significant at 16 hpf (p < 0.001), indicating that while dorsal cell migration is not affected by MO-injection, medial cell migration is specifically affected. A-E: scale bar = 100 μm. G-I: error bars = SEM. NS = not significant.