Hair bundle density in the lagena. (A) Lagena schematic showing the three sampling locations, with an example of location 2 shown in the confocal image. All boxes are 50 × 50 μm and are drawn to scale. (B) For *AB and transgenic lines created on the *AB background, bundle density is significantly different between genotypes and sampling regions (2-way ANOVA, F5,160 = 8.91, p < 0.001; and F2,160 = 43.02, p < 0.001, respectively). In sampling region 3, bundle density is significantly higher in Bcl2 fish than in *AB fish (Bonferroni-corrected posthoc, ***p < 0.001). (C) There is a significant difference in lagenar bundle density between wildtype lines (2-way ANOVA, F2,68 = 9.08, p < 0.001 for genotype main effect), with WIK fish having higher density in region 3 than AB fish (*p < 0.05). (D) There is no difference in bundle density between ET4 and TL fish (2-way ANOVA, F1,24 = 0.40, p = 0.53 for genotype main effect). Data are presented as mean ± S.E. N = 8–17 fish per genotype.