Fig. 5. Concomitant time-course distribution of βV spectrin and prestin in OHCs. (A) A model illustrating the role of the II-βV spectrin network in the OHC lateral wall. The II-βV spectrin heterotetramers crosslink adjacent circumferential actin filaments, while extending out of the plane (25 nm) to reach the plasma membrane, which is densely packed with the prestin motor protein. (B) An F-actin-labeled cochlea illustrating the different positions (base, middle and apex) along the cochlea longitudinal axis. (C) Whole-mount immunofluorescence analysis of βV spectrin and prestin distributions in the basal (0-20%), middle (40-60%) and apical (80-100%) turns of the cochlea. Consistent with the progressive maturation of the cochlea, the intensities of βV spectrin and prestin stainings in OHCs increase from P2 to P10, and from the basal to the apical zone of the cochlea. Scale bars: 5 µm.