Ultracytochemical study of the stria vascularis of the guinea pig cochlea.

The localization of the K-NPPase, ALPase and Mg-ATPase activities in the stria vascularis of the guinea pig cochlea was ultracytochemically studied. The K-NPPase reflecting the Na-K-ATPase activity was localized on the cytoplasmic side of the deeply infolded basolateral plasma membrane of the marginal cells. On the other hand, activities of ALPase and Mg-ATPase were found in the intercellular spaces between the marginal and the intermediate or the basal cells. The surface of the stria vascularis facing to endolymph showed only the Mg-ATPase activity. The ALPase activity localized also around the capillaries. The mechanism of the K and Na transport was discussed.