Fig. 5. Inhibition of the Wnt signaling prevents stereociliary bundle reorientation. (A) Secreted frizzled-related protein 1 (Sfrp1) inhibits stereociliary bundle reorientation. Average stereociliary bundle orientations were determined for outer hair cells at specific positions along the basal-to-apical axis of the cochlea in control and Sfrp1-treated cultures. Exposure to Sfrp1 inhibited bundle reorientation with significant differences in average stereociliary bundle orientation at both the 5% and 12.5% positions (*P<0.02, **P<0.003). (B) Wnt inhibitory factor 1 (Wif1) inhibits stereociliary bundle reorientation. Average stereociliary bundle orientations were determined for outer hair cells at the 5% and 12.5% positions along the basal-to-apical axis of the cochlea in control and Wif1-conditoned media cultures. Wif1-conditioned medium significantly inhibited stereociliary bundle reorientation at both positions (*P<0.001). (C) Sodium chlorate inhibits stereociliary bundle reorientation. Diffusion of Wnt protein within cochlear explants was reduced by inhibition of synthesis of HSPG with 30 mM sodium chlorate (NaClO₃). NaClO₃-treated cultures exhibited significant differences, as compared with control, in average bundle orientations at the 5%, and 12.5% positions (*P<0.004). Results for all three graphs are from a minimum of three control and three experimental cochleae and orientations were determined for a minimum of 12 stereociliary bundles at each position in each sample. Error bars indicate s.e.m.

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