Perilymphatic fluid compartments and intercellular spaces of the inner earand the organ of Corti

An in vitro preparation of the inner ear cochlea has been used to visualize the structural relationships of unfixed, living sensory cells and structur al components within the intact hearing organ. By perfusing perilymphatic c ompartments of the cochlea with fluorochrome-conjugated dextran, the extrac ellular spaces mere clearly outlined, The staining pattern illustrated the large fluid compartments formed by the tunnel of Corti, the space of Nuel, and the outer tunnel. The dextran solution also indicated the spaces betwee n the outer hair cell rows, the inner hair cells, and the surrounding suppo rting cells. The staining pattern demonstrates that the organ of Corti has a loose structure, suggesting a weak mechanical coupling between the cells. Moreover, it is evident that substances applied to the perilymph (e.g., th erapeutic drugs) will readily reach all the cells of the hearing organ. In addition to the intraorgan fluid compartments, the spiral limbus was shown to contain significant volumes of perilymph within the intercellular spaces forming the so-called teeth of Huschke between the interdental cells, An e xtensive system of bundles following the teeth of Huschke was shown to be c ompletely immersed in perilymph, The bundles were stained by a potentiometr ic dye, which in the inner ear primarily stains nerve fibers and sensory ce lls, which may indicate a nervous control of cells in this region. (C) 2000 Academic Press.