Fig. 6

edn1 positively and hand2 negatively regulate the volume of pharyngeal arch fli1a:EGFP expressing mesenchyme (A) and ventral domain proliferation of neural crest derived cells (B–E).

Data are for 28 hpf, a minimum of 23 individuals of each genotype were sampled. (B) shows an example 2-color image of phospho-histone H3 labeling for mitosing cells (red) and fli1a:EGFP expression (green). (C–E) show mean counts of double-labeled cells ±SEM. Tukey-Kramer comparison of the mean volumes (in A) reveals that the edn1 mutant volume is significantly lower than WT, and that the hand2 mutant volume is significantly higher (P<0.05). Statistically the double mutant phenotype is neither different from the edn1 mutant nor WT, suggesting some degree of phenotypic rescue of arch volume when hand2 does not function. Tukey-Kramer analysis of the levels of proliferation in both the total mesenchyme (C) and ventral sector of mesenchyme (E) reveals three statistically distinctive classes, WT, the single hand2 mutant, and the single edn1 plus edn1;hand2 mutant class (P<0.05). Genotypic differences for the dorsal mesenchyme (D) are insignificant.