F-ACTIN, TUBULIN AND SPECTRIN IN THE ORGAN OF CORTI - COMPARATIVE DISTRIBUTION IN DIFFERENT CELL-TYPES AND MAMMALIAN-SPECIES

Laser scanning confocal microscopy was used to determine the distribution of actin, spectrin and tubulin in whole mounts of the organ of Corti of guinea pig, monkey, rat and chinchilla. Actin, spectrin and tubulin were localized in all cell types in the auditory epithelium. No specialized cytoskeletal organization of tubulin was detected in the cytoplasmic domain of hair cells. The only specialized organization of actin and spectrin in the cytoplasmic domain was the infra-cuticular network, found exclusively in apical guinea pig outer hair cells. In contrast, the lateral wall of inner and outer hair cells contained a homogenous distribution of label specific for actin and spectrin. The label intensity was similar in the base and the apex of the cochlea. These results indicate that the distribution of spectrin and actin in the auditory epithelium is similar to that in other epithelial cells, suggesting that actin and spectrin participate in the formation of cellular shape and possibly in docking molecules to the membrane.