Figure 4: Distribution of ryanodine receptors (RyRs, green) in nonsensory epithelia of the frog canal. Representative immunofluorescence confocal stacks obtained from dark cells, transitional cells, and ductus cells. Both dark cells and ductus cells were positive for RyR, whereas labeling of transitional cells was absent or faint. In ductus cells, RyRs appear localized to a perinuclear formation. Inset shows a single cell at higher magnification. The micrographs are representative of six separate experiments. Bar: 20 μm. A schematic representation of the distribution of different epithelial cell types in the semicircular canal is also shown.