Ultrastructural changes of inner cells. (A) Small number of vacuoles in inner hair cells and intact cell shape in P10 cCx26ko mice (magnification, ×2,850; middle turn). Arrow, vacuoles. (B) Increased number of lysosomes and swollen mitochondria in inner hair cells in P18 cCx26ko mice (magnification, ×3,800; middle turn). Arrows, mitochondria. (C and D) Thinning of dense cuticular plate in inner hair cells at P30 in cCx26ko mice compared with P30 wild-type mice (magnification, ×4,800; middle turn). Arrows, dense cuticular plate. (E and F) Deformed inner hair cells of the basal turn with (E) empty spaces, arrows, from degenerated cells in P60 cCx26ko mice (magnification, ×2,800; basal turn). (F) Arrows, mitochondria with myelin in inner hair cells of P90 cCx26ko mice (magnification, ×2,800, apical turn). IPC, inner pillar cells; OPC, outer pillar cells; IHC, inner hair cells; cCx26ko, conditional connexin 26 knockout.