Structural relationships of the unfixed tectorial membrane

Although the tectorial membrane has a key role in the function of the organ of Corti, its structural relationship within the cochlear partition is sti ll not fully characterised. Being an acellular structure, the tectorial mem brane is not readily stained with dyes and is thus difficult to visualise. We present here detailed observations of the unfixed tectorial membrane in an in vitro preparation of the guinea pig cochlea using confocal microscopy . By perfusing the fluid compartments within the cochlear partition with fl uorochrome-conjugated dextran solutions, the tectorial membrane stood out a gainst the bright background. The tectorial membrane was seen as a relative ly loose structure as indicated by the dextran molecules being able to diff use within its entire volume. There were, however, regions showing much les s staining, demonstrating a heterogeneous organisation of the membrane. Esp ecially Hensen's stripe and regions facing the outer hair cell bundles appe ared more condensed. Whereas no connections between Hensen's stripe and the inner hair cell bundles could be observed, then was clearly a contact zone between the stripe and the reticular lamina inside of the inner hair cell. (C) 2001 Elsevier Science B.V. All rights reserved.