Hair cell counts in the prosaposin knock-out mice. A, Representative samples of phalloidin-stained cochlear preparations in the base and apex of WT and KO mice. There is a loss of OHCs in the apex of the KO mice. B, Hair cell cytocochleogram in the organ of Corti. Compared with WT mice, there is a loss of up to 40% of OHCs in the cochlear apex of the prosaposin KO mice, extending through the first 2 mm of the cochlear duct. In contrast, IHC numbers are normal throughout the cochlea.