The tectorial membrane of the rat

Abstract

Histochemical, x-ray analytical and scanning and transmission electron microscopical procedures have been utilized to determine the chemical nature, physical appearance and attachments of the tectorial membrane in normal rats and to correlate these results with biochemical data on protein-carbohydrate complexes. Additionally, pertinent histochemical and ultrastructural findings in chemically sympathectomized rats are considered. The results indicate that the tectorial membrane is a viscous, complex, colloid of glycoprotein(s) possessing some oriented molecules and an ionic composition different from either endolymph or perilymph. It is attached to the reticular laminar surface of the organ of Corti and to the tips of the outer hair cells; it is attached to and enclose the hairs of the inner hair cells. A fluid compartment may exist within the limbs of the “W” formed by the hairs on each outer hair cell surface. Present biochemical concepts of viscous glycoproteins suggest that they are polyelectrolytes interacting physically to form complex networks. They possess characteristics making them important in fluid and ion transport. Furthermore, the macromolecular configuration assumed by such polyelectrolytes is unstable and subject to change from stress or shifts in pH or ions. Thus, the attachments of the tectorial membrane to the hair cells may play an important role in the transduction process at the molecular level.