The ultrastructure of the supporting system in the guinea pig semicircular canal.

The ultrastructure of the perilymphatic space of the guinea pig semicircular canal was examined, using thin sectioning, scanning electron microscopy and freeze-fracture methods. The perilymphatic space was divided into two parts: an area of fibrous matrix and an area of fibroblasts with bundles of fine filaments. In the area of fibroblasts, cell processes and filament bundles formed a meshed pattern. The cell processes were interconnected with each other by both intermediary and gap junctions. The inner surface of the osseous semicircular canal was covered with multilayers of cell processes of both fibroblasts and mesothelial cells. The fact that tight and gap junctions were observed between the cell processes suggests a functional significance in these structures.