ENZYME-HISTOCHEMICAL LOCALIZATION OF CARBONIC-ANHYDRASE IN THE INNER-EAR OF THE GUINEA-PIG AND SEVERAL IMPROVEMENTS OF THE TECHNIQUE

We have made several improvements in the method of fixation of the inn er ear and the enzyme-histochemical technique for carbonic anhydrase ( CA) detection. The results confirmed that CA is localized in the hair cells of the organ of Corti, Deiters' cells or nerve endings, inner pi llar cells, Boettcher's cells, stria vascularis, spiral ligament, spir al limbus, and spiral ganglion cells. These results generally agree wi th previous histochemical observations but showed some differences, Ou r method preserved tissue morphology and showed more detailed localiza tion of CA activity in the inner ear. In particular, the marginal zone of stria vascularis and the epithelial cells of spiral prominence, fa cing the endolymph, showed no CA activity, while the suprastrial regio n of the spiral ligament and the supralimbal region of the spiral limb us, juxtaposed to the perilymph, showed CA activity, In outer hair cel ls, the cuticular plate, which faces the endolymph showed CA activity, but the lateral membrane, which faces the perilymph showed no CA acti vity. In contrast, the inner hair cell cytoplasm showed diffuse CA act ivity, These results will be useful in considering ion exchange betwee n endolymph and its adjacent cells, and between perilymph and its adja cent structures.