EXPRESSION OF S100-BETA IN SENSORY AND SECRETORY-CELLS OF THE VERTEBRATE INNER-EAR

We evaluated anti-S100 beta expression in the chick (Gallus domesticus ) inner ear and determined that: 1) the monomer anti-S100 beta is expr essed differentially in the vestibular and auditory perikarya; 2) expr ession of S100 beta in the afferent nerve terminals is time-related to synapse and myelin formation; 3) the expression of the dimer anti-S10 0 alpha alpha beta beta and monomer anti-S100 beta overlaps in most in ner ear cell types. Most S100 alpha alpha beta beta positive cells exp ress S100 beta, but S100 beta positive cells do not always express S10 0 alpha alpha beta beta. 4) the expression of S100 beta is diffused ov er the perikaryal cytoplasm and nuclei of the acoustic ganglia but is concentrated over the nuclei of the vestibular perikarya. 6) S100 beta is expressed in secretory cells, and it is co-localized with GABA in sensory cells. 7) Color thresholding objective quantitation indicates that the amount of S100 beta was higher (mean 22, SD +/- 4) at E19 tha n at E9 (mean 34, SD +/- 3) in afferent axons. 8) Moreover, S100 beta was unchanged between E11-E19 in the perikaryal cytoplasm, but did cha nge over the nuclei. At E9, 74%, and at E21, 5% of vestibular perikary a were positive. The data suggest that S100 beta may be physically ass ociated with neuronal and ionic controlling cells of the vertebrate in ner ear, where it could provide a dual ionic and neurotrophic modulato ry function.