S-100 immunoreactivity identifies a subset of hair cells in the utricle and saccule of a fish.

Certain hair cells of fish exhibit strong immunoreactivity to an S-100 antibody. By their spatial locations in the utricle and saccule, these hair cells appear to possess a relatively short kinocilium and a roughly ovoid cell shape. In the utricle, these cells are predominantly located in the striola. In the saccule, these cells are found within the central area of the epithelium. In both of these epithelia the strongly immunoreactive hair cells coincide with the locations of hair cells possessing F1 ciliary bundles.