THE LOCALIZATION OF TAURINE-LIKE IMMUNOREACTIVITY IN THE ORGAN OF CORTI - A SEMIQUANTITATIVE, POSTEMBEDDING IMMUNOELECTRON MICROSCOPIC ANALYSIS IN THE RAT WITH SOME OBSERVATIONS IN THE GUINEA-PIG

The cellular and subcellular localization of taurine in the organ of C orti was examined by means of postembedding immunocytochemistry. Suppo rting cells, including border cells, inner phalangeal cells, Deiters c ells, pillar cells, and Bottcher cells are enriched in taurine-like im munoreactivity, contrasting sharply with inner and outer hair cells wh ich 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 sho wed similar labelling patterns. The present immunocytochemical finding s indicate that supporting cells are the plausible sources of the repo rted potassium-induced taurine release in the cochlea. The distributio n of taurine in the organ of Corti is not compatible with a transmitte r or neuromodulatory action of this amino acid, but rather suggests an involvement in osmoregulatory functions.