Other proteins common to the calyceal processes of photoreceptors and the stereocilia of hair cells. (A) Schematic diagrams illustrating the differences in architecture of the apical-most inner segment regions of mouse and macaque photoreceptors, and summarizing the subcellular distribution of USH1 and USH2 proteins. In the diagram of the rod cell, the calyceal processes are not presented, to visualize the distribution of USH1 proteins at the junction between inner and outer segments. The precise boundaries of the USH1 protein labeling in this region (green) remain to be established. (B–D) Myosin IIIa, PMCA2, and espin in the photoreceptor calyceal processes. Glutamylated tubulin (blue) and cone opsin (red) labeling was used to visualize the connecting cilium and the cone outer segment, respectively. (E and F) Espin labeling in the calyceal processes of a cone photoreceptor cell (E) and the hair bundle of an auditory hair cell (F). The scanning electron microscopy images show the architecture of the calyceal processes of a cone photoreceptor (E) and an auditory sensory cell’s hair bundle (F). Bars, 2 µm.