Differences of inner and outer hair cells in the organ of Corti of the guinea pig in respect to the cellular content of precipitable calcium.

Differences between inner and outer hair cells in the cellular content of precipitable calcium were detected using a potassium pyroantimonate precipitation method and the electron spectroscopic imaging (ESI-) technique. The cytoplasm of the inner hair cells was scattered with a high number of calcium precipitates in all analysed animals, but only a few reaction products could be identified in the cytoplasm of the outer hair cells in all analyzed specimens. Even the well developed system of the subsurface fenestrated cisternae in the outer hair cells was nearly empty of calcium precipitates. A relatively high amount of reaction products could be identified in the nuclei of both types of nerve endings of the receptor cells. Significant differences regarding the content of precipitable calcium were found in the different types of nerve endings, which come into contact with the basal parts of both receptor cells. The observed differences in the content of precipitable calcium between the two types of hair cells are discussed with respect to their probable different roles in signal transduction processes.