Freeze-etch visualizations of some elements in the stria vascularis.

A quick-freeze, deep-etch study was made to observe the three-dimensional aspect of both membranes and organelles in the stria vascularis of the guinea pig. Our replicas showed various membrane characteristics of the vesicles, e.g., a clathrin basket on the inner surface membrane, aggregation of membrane particles on the protoplasmic fracture face, and regularly arranged surface protuberances on the outer surface membrane. In the cell processes of marginal cells, there were not only bundles of microtubules but also another type of fibril. Many gap junctions were observed between marginal, intermediate, and basal cells. In some replicas, the inner surfaces of the gap junctions were covered with particle protrusions with some ordered arrangements. The functional roles of these elements in the stria vascularis are discussed.