Protein patterns in human vestibular ganglion cells and hair cells, with functional interpretations

Cytoskeletal organization was analysed in the vestibular ganglion cells and in the sensory epithelia of all five vestibular organs of the adult human temporal bone. A pancellular rigidity of the upper surfaces of the vestibular organs, evidenced by large quantities of intermediate filaments and actin, seems of importance for the mechanoelectrical transduction by opposing the motion of the cupulae and statoconial layers. Immunostaining for the calcium-binding protein synaptophysin in the sensory hair bundles and in the area close to the cuticular plates--the first of its kind to be demonstrated in human vestibular organs--indicates the presence of calcium-dependent ionic channels. The hypothesis is presented that the calyx might be involved in a short-loop feed back control of type I hair cells, i.e. of the mechanoelectrical transduction itself. Subpopulations of vestibular ganglion cells were identified by the staining pattern of cytoskeletal proteins, but not by ordinary ultrastructural analysis.