Figure 9.
Immunogold labeling for spectrin, β-actin, and γ-actin. A–E, Rat OHCs. F, G, Guinea pig OHCs. A, Spectrin is distributed throughout the cuticular plate and is evident beneath the apical membrane and along the lateral margins (arrowheads). Labeling also occurs over the rootlets (arrow). B, Spectrin labeling is evident not only in the subapical layer (arrowheads) and rootlets (arrow) but also in the ankle region (asterisk) and stereocilia (s). C, β-Actin labeling is denser over the stereocilia and rootlets than the main matrix of the cuticular plate. A labeled rootlet extends below the cuticular plate (arrow). D, As well as prominent in the rootlets (r), β-actin labeling is concentrated over the dark meshwork regions of the plate (arrows). E, The labeling density for γ-actin is similar in the stereocilia and cuticular plate. Rootlets are also labeled, one extending deeper than the cuticular plate (arrow). F, γ-Actin labeling (small particles) is also strongest over the dense patches associated with the meshwork (arrows). Large particles represent β-actin. G, γ-Actin labeling is continuous from the cortical lattice (arrowheads) into the cuticular plate (cp). Scale bars: A, C, E, 400 nm; B, D, 200 nm; F, G, 100 nm.