Molecular organization and fine structure of the human tectorial membrane: is it replenished?
Auditory sensitivity and frequency resolution depend on the physical properties of the basilar membrane in combination with outer hair cell-based amplification in the cochlea. The physiological role of the tectorial membrane (TM) in hair cell transduction has been controversial for decades. New insights into the TM structure and function have been gained from studies of targeted gene disruption. Several missense mutations in genes regulating the human TM structure have been described with phenotypic expressions. Here, we portray the remarkable gradient structure and molecular organization of the human TM. Ultrastructural analysis and confocal immunohistochemistry were performed in freshly fixed human cochleae obtained during surgery. Based on these findings and recent literature, we discuss the role of human TMs in hair cell activation. Moreover, the outcome proposes that the α-tectorin-positive amorphous layer of the human TM is replenished and partly undergoes regeneration during life.
KeywordsTectorial membrane Human Electron microscopy α-tectorin
Inner hair cell
Outer hair cell
Scanning electron microscopy
Transmission electron microscopy
This study was supported by ALF grants from Uppsala University Hospital and Uppsala University and by the Tysta Skolan Foundation, Swedish Deafness Foundation (HRF) and Land Tirol Technologie Förderungsprogram, Förderung von Wissenschaft, Forschung und Entwicklung (Programm K-Regio Vamel) and Med El, Innsbruck, Austria. Our research is part of the European Community 7th Framework Programme on Research, Technological Development and Demonstration. Project acronym: NANOCI. Grant agreement no: 281056. It was also supported by kindly donated private funds from Börje Runögård, Sweden. Dr. Klaus Qvortrup is acknowledged for providing oxygenated fluorocarbon fixative for the TEM investigation.
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