Localization of Na+, K+-ATPase activity in the tegmentum vasculosum of the chick cochlea.

We studied the localization of Na+, K+-ATPase activity in the chick cochlea, utilizing a cytochemical method of K+-p-nitrophenylphosphatase (K+-NPPase), and found that the enzyme activity was limited to the dark cells of the tegmentum vasculosum (TV). Our present results indicate that the dark cells of the TV play an essential role in the maintenance of the ionic composition of the cochlear endolymph.