COLLAGEN OF ACCESSORY STRUCTURES OF ORGAN OF CORTI

It was previously demonstrated that about 40% of the protein of the tectorial membrane of the guinea pig consists of collagen type II, with lesser amounts of type IX and XI. In this paper we extend these studies on the tectorial membrane to the basilar membrane and to other accessory structures, the spiral ligament and spiral limbus. Earlier immunohistochemical data indicated that no collagen type II is present in the basilar membrane of the newborn guinea pig, but that it is present in the area of the basilar membrane in the embryo. However, by means of stringent extraction procedures we have determined biochemically that collagen type II and lesser amounts of type XI are present in the basilar membrane of the adult guinea pig, at similar levels (on the basis of total protein) to the tectorial membrane. Levels of collagen type II are much lower in the spiral ligament and spiral limbus. The presented studies demonstrate that classical techniques of collagen chemistry can be applied at the microscale on minute tissue elements. The significance of the presence of collagen in the tectorial membrane and basilar membrane is discussed in the light of known mechanical properties of these structures.