Reissner's Membrane: An Ultrastructural Study

Abstract

REISSNER'S membrane¹separates scala media from scala vestibuli. It extends from the limbus to the stria vascularis at its superior extent. Until Naftalin and Harrison²proposed that it served as a filter allowing the passage of sodium, but not potassium, ions from scala media to scala vestibuli, Reissner's membrane was assumed to function as a simple isolator. The thickness and relatively large number of cells in the lower layer, together with the increased surface area (microvilli), led Lawrence et al³to speculate that Reissner's membrane might well be a selectively absorbing tissue. Whether or not it serves this function is important to longitudinal and radial theories of endolymph flow.^2-12The authors therefore feel that an ultrastructural description is timely. <h3>Methods and Materials</h3> Dark young guinea pigs weighing between 250 and 350 gm were decapitated, the bulli removed, the labyrinth opened and perfused with 2% veronal acetate buffered osmium tetroxide within