Cytochemical localization of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase in the guinea pig inner ear. Evaluation of the cerium-based method vs. the lead-based method.

The cytochemical localization of ouabain-sensitive, potassium-dependent p-nitrophenylphosphatase in the guinea pig inner ear was studied using both the lead-based method and the cerium-based method. The influence of primary fixation and incubation time was investigated under both incubation conditions. A high p-NPPase activity was observed in the basolateral infoldings of the stria vascularis in the cochlea and the dark cells in the vestibular labyrinth. The stromal cells of the spiral prominence only showed a weak reaction with the lead-based method. No specific enzyme activity was found in the endolymphatic sac. The results of the present study are discussed with emphasis on the cation transport mechanisms of the inner ear.