Outer hair cell stereocilia attachment to the tectorial membrane

In the chinchilla, attachment of the hair cell stereocilia to the tectorial membrane appears to occur at the distal tips of the longest rows of stereocilia of the outer hair cells. The present report investigates the macromolecules involved in this attachment and their relationship with the type B fibrils of the tectorial membrane. Cochleas were fixed and stained with glutaraldehyde/Cuprolinic blue and revealed sulfated macromolecules at the tips of the longest rows of the outer hair cell stereocilia. These macromolecules extend from the tips of the stereocilia into cup-shaped attachment sites of the tectorial membrane which consist only of type B fibrils. It is not know whether these macromolecules form direct or indirect links with the type B fibrils of the tectorial membrane. This attachment would provide a firm contact between the tectorial membrane and the hair cell. However, since these attachments are limited only to the distal tips of one row of the hair cell stereocilia they may be vulnerable to acoustic overstimulation. [Work supported by the NIDCD.]