Three-dimensional structure of outer hair cell pillars.

UNLABELLED: CONCLUSIONS. Electron tomography was used to generate three-dimensional reconstructions of the pillars that connect the cell membrane with the cytoskeleton of the outer hair cell. Results are consistent with the hypothesis that pillars are important for mechanically linking the membrane with the cytoskeleton. OBJECTIVE: To make a qualitative assessment of the morphology of the sub-membrane pillars of cochlear outer hair cells. MATERIALS AND METHODS: Guinea pig cochleae were fixed and prepared for electron microscopy using protocols described previously. Sections were imaged on an electron microscope equipped with a goniometer. The specimens were tilted through a range of 120°, and an image was acquired at each tilt angle. Filtered back-projection was used to generate three-dimensional reconstructions. RESULTS: Twelve individual pillars were successfully reconstructed. Pillars often connect to the cell membrane through a thin segment, and to the cytoskeleton through a forking structure that may form a central cavity.

Micro-lesions in Reissner's membrane evoked by acute hydrops.

In some pathological conditions excessive amounts of endolymph can accumulate and cause swelling, hydrops, of the membranous labyrinth. Reissner's membrane in the cochlea will distend and may even rupture. We have studied the effects of acute hydrops, followed for up to 5-6 h, in a preparation that allows continuous monitoring of structural alterations in individual cells in Reissner's membrane. This is accomplished by using laser confocal microscopy on the membrane visualized by labeling its cells with fluorescent dyes. In specimens subjected to hydrops it was observed that discrete structural defects developed in Reissner's membrane. These were seen as lesions in single cells or in groups of cells in the epithelial layer. It is suggested that through these micro-lesions the electro-chemical environment of the organ of Corti can be altered causing hearing loss and tinnitus during hydrops.