DISTRIBUTION OF ACTIN IN DEVELOPING OUTER HAIR-CELLS IN THE GERBIL

During the two weeks following the onset of cochlear function in the g erbil, active cochlear processes appear to mature. The active cochlear processes likely involve outer hair cells with their specialized late ral wall structures, including the subsurface cisternae and associated cytoskeletal elements. We have previously demonstrated that the subsu rface cisternae mature gradually during the time that active cochlear processes mature in the gerbil. In the study reported here, we used po stembedding immunocytochemical electron microscopy to investigate whet her actin labelling associated with the cortical cytoskeleton of the g erbil outer hair cell increased concomitantly. In contrast to the grad ual development of the subsurface cisternae, actin labelling in the re gion of the cortical cytoskeleton significantly increased during the o nset of cochlear function and maintained this level during the time th at active cochlear processes mature. Thus, it appears that increased a ctin adjacent to the lateral plasma membrane of the outer hair cell is related to the onset of cochlear function rather than to the maturati on of active cochlear processes.