Keratins as markers of differentiated taste cells of the rat.

Cytokeratins in taste buds were immunocytochemically evaluated with monoclonal antibodies. In each of six different epithelial sites in the rat oral cavity, intragemmal cells of taste buds were immunoreactive for keratin polypeptides 8, 18, and 19, as well as for keratin 7, which has not been previously reported in taste buds. Keratin-18-like immunoreactivity was present in fewer than half of the intragemmal cells, whereas all intragemmal cells were immunopositive for keratins 7, 8, and 19. Apart from some salivary duct cells, no other cells in the tongue were immunoreactive for any of these four keratins. Morphological and immunocytochemical profiles indicate that taste buds are islets of simple epithelium embedded in an expanse of stratified squamous epithelium. These simple epithelial cells and their keratins are nerve-dependent, since denervation eliminated all four keratins and replaced elongated taste cells of the vallate papilla with stratified squamous epithelium. We conclude that antibodies against keratins 7, 8, or 19 are useful markers for intragemmal cells in studies of taste bud development, degeneration, regeneration, turnover and tissue culture.