Fig. 2. Spectrin subunits are present in different subcellular regions in outer and inner hair cells. (A-D) Cross-sections through organs of Corti from P8-P10 mice. The mammalian cochlea contains two classes of hair cells: inner and outer hair cells (IHCs and OHCs, respectively; labeled with an anti-myosin-VIIa antibody, B). Whereas the II- and βII-spectrin subunits are detected in both types of hair cells and flanking supporting cells (A,C), βV spectrin is restricted to the hair cells (D). Asterisks indicate positions of the sensory hair cells. (E-I) Isolated hair cells. (E) In IHCs, βV spectrin displays a cytoplasmic staining, with a strong submembrane labeling at the neck region of the cell. (F) βII spectrin is detected in the cuticular plate. (G) In OHCs, the βV spectrin labeling extends all along the lateral wall, similar to that of prestin. (H,I) In these cells, the βII-spectrin subunit predominates in the cuticular plate (H), whereas the II subunit is detected in both the cuticular plate and along the lateral wall (I). Scale bars: 5 µm.