dbh and th expression in cervical sympathetic ganglia of wild type and hands off mutants. Whole-mount in situ hybridizations for hand2 (A,D,G,J), dbh (B,E,H,K) and th (C,F,I,L) viewed from dorsal after dissection of the yolk sac and spinal cord. hand2 labels sympathetic ganglia (indicated by dashed circle) and more ventrally located enteric neurons (diffuse staining below the focal plane; white arrowheads) that migrate to a more lateral position at 3 dpf (G). hands off embryos at 2 dpf (D) and 3 dpf (J) are devoid of hand2 expression and display only very few dbh+ (E,K) and th+ cells (F,L). (M) Area of dbh-expressing cells at 2 and 3 dpf in hands off mutants compared with wild type. (Number of embryos analysed: nine wild type, three mutant for 2 dpf; 11 wild type, seven mutant for 3 dpf.) (N) Area of th-expressing cells at 2 and 3 dpf in hands off mutants compared with wild type. Data are presented as mean ± s.e.m. (Number of embryos analysed: 28 wild type, ten mutant for 2 dpf; 41 wild type, 16 mutant for 3 dpf.) The injection of wild-type hand2 mRNA resulted in a significant increase in the number of th-expressing cells in hands off mutants analysed at 2 dpf (n=10). (**P<0.01; ***P<0.001.)
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