The localization of taurine-like immunoreactivity in the organ of Corti: a semiquantitative, post-embedding immuno-electron microscopic analysis in the rat with some observations in the guinea pig.

The cellular and subcellular localization of taurine in the organ of Corti was examined by means of postembedding immunocytochemistry. Supporting cells, including border cells, inner phalangeal cells, Deiters cells, pillar cells, and Böttcher cells are enriched in taurine-like immunoreactivity, contrasting sharply with inner and outer hair cells which did not show noteworthy immunolabelling. Immunogold cytochemistry indicated an even distribution of taurine throughout the cytoplasm and karyoplasm of the labelled supporting cells. Rats and guinea pigs showed similar labelling patterns. The present immunocytochemical findings indicate that supporting cells are the plausible sources of the reported potassium-induced taurine release in the cochlea. The distribution of taurine in the organ of Corti is not compatible with a transmitter or neuromodulatory action of this amino acid, but rather suggests an involvement in osmoregulatory functions.