Fig. 4. phox2b and ascl1 expression in cervical sympathetic ganglia of wild type and hands off mutants. phox2b and ascl1 whole-mount in situ hybridizations viewed from dorsal. phox2b labels sympathetic ganglia (dashed circle) and more ventrally located enteric neurons (diffuse staining from below focus plane; white arrowheads). The gut was removed from ascl1-stained embryos. Control and hands off embryos show the same expression of phox2b at 2 dpf (A,C) and 3 dpf (E,G). Also ascl1 expression is not affected in hands off embryos at 2 dpf (B,D) and 3 dpf (F,H). The area and intensity of ascl1 expression is, however, strongly reduced at 3 dpf for both wild-type and hands off embryos. (I) Area of phox2b-expressing cells at 2 and 3 dpf in hands off mutants compared with wild type. (Number of embryos analysed: 15 wild type, five mutant for 2 dpf; 12 wild type, four mutant for 3 dpf.) (J) Area of ascl1-expressing cells at 2 and 3 dpf in hands off mutants compared with wild type. (Number of embryos analysed: ten wild type, seven mutant for 2 dpf; four wild type, four mutant for 3 dpf.) Data are presented as mean ± s.e.m.; n.s. not significant. phox2b staining of epibranchial placodes is indicated by asterisks.