DISTRIBUTION OF CYTOKERATINS IN THE VESTIBULAR EPITHELIUM OF THE GUINEA-PIG

Cytokeratin expression in the vestibular labyrinth of the guinea pig w as investigated with immunofluorescence and immunoperoxidase staining on surface preparations of the vestibular epithelium. Phalloidin, an F -actin-specific probe, was used to distinguish between hair cells and supporting cells. Cytokeratin expression was not found in the cytoplas mic domain of hair cells of the crista ampullaris, utricle, or saccule . Cytokeratin expression was abundant in supporting cells of the vesti bular sensory epithelium. Electron microscopy revealed the presence of desmosomes, which are associated with cytokeratins, within type 2 hai r cells of the vestibular epithelium. It appears that cytokeratins are absent within the cytoplasmic domain of hair cells, but are present i n association with intercellular junctions. The functional significanc e of this unique pattern of cytokeratin expression within the vestibul ar epithelium is discussed.