Three-dimensional observation of the cochlea. Intracellular structure of the hair cell and the supporting cell.

Intracellular structures of the guinea pig cochlea were observed by scanning electron-microscopy. The cochlea was freeze-fractured and then macerated with 0.1% OsO4 solution (aldehyde-osmium-DMSO-osmium (AODO) method). Intracellular organelles, such as mitochondria, endoplasmic reticulum (ER), and Golgi apparatus, were demonstrated stereoscopically. The ER of the outer hair cell showed the most interesting features, such as subsurface cisternae and lamellar body. The subsurface cisternae which formed a stratiform network covered the inner surface of the cell membrane of the supranuclear part. Variously shaped mitochondria were found on the innermost layer of the subsurface cisternae. The lamellar body consisted of dilated cisternae and tubules of ER. The tubular ER of the lamellar body were contiguous with the subsurface cisternae. The pillar cells, Deiters' cells and Hensen's cells had well-developed tubular ER, while Claudius' cells had poorly developed tubular ER.