Quantifications of hair cell patterning defects in Hey2 mutants. Extra rows of outer hair cells and inner hair cell doublets were quantified in the cochleae isolated from animals with the genotypes specified (A). The percent of the number of hair cells in extra rows was calculated against the number of normally patterned hair cells in the same cochlea, and plotted for each genotype specified in the graph (B). The distribution of mis-patterned hair cells along the longitudinal axis of the cochlea was indicated (B). Note the uniform increase of ectopic hair cells along the longitudinal axis of the cochlea in Hey2-/-;Hes5-/- and Hey2+/-;Hes1-/- mutants. The p values for statistic significance among the groups in each bracket are indicated (A,B).