STEREOCILIARY CROSS-LINKS BETWEEN ADJACENT INNER HAIR-CELLS

An extensive network of intracellular cross-links occurs between the stereocilia of each cochlear hair cell bundle. These links fall into two main categories; lateral links which run roughly horizontal with respect to the reticular lamina and which join stereocilia of the same or adjacent rows, and tip-to-side links which run at a more vertical angle from the tip of each shorter stereocilium to the side of the adjacent longer stereocilium in the row behind. It has been proposed that deformation of the tip-to-side links caused alteration of the rate of opening of ion channels, producing transduction. Lateral linkages also occur between the stereocilia of adjacent hair cells. Now, intracellular links which resemble the tip-to-side links have been observed. Some of these occur in positions inappropriate to their proposed role in tranduction. Severan hypotheses are proprosed to account for their presence e.g., the links could represent the remnants of a glycocalyx which is best preserved in areas where stereocilia are closely opposed.