ELLIPTIC-P CELLS IN THE AVIAN PERILYMPHATIC INTERFACE OF THE TEGMENTUM-VASCULOSUM

Elliptical cells (E-P) are present at the perilymphatic interface lume n (PIL) of the lagena. The E-P cells often separate from the tegmentum vasculosum (TV) and have touching processes that form a monolayer bet ween the K+ rich perilymph and the Na+ rich endolymph, similar to the mammalian Reissner's membrane. We examined the TV of chicks (Gallus do mesticus) and quantitated the expression of anti-S100 alpha alpha beta beta and S100 beta. There was a 30% increase of S100 beta saturation in the light cells facing the PIL when compared to other TV light cell s. We show that: (1) the dimer anti-S100 alpha alpha beta beta and the monomer anti-S100 beta are expressed preferentially in the light cell s and the E-P cells of TV; (2) expression of S100 beta is higher in li ght cells facing the PIL than in adjacent cells; (3) the expression of the dimer S100 alpha alpha beta beta and monomer S100 beta overlaps i n most inner ear cell types, including the cells of the TV, most S100 alpha alpha beta beta positive cells express S100 beta, but S100 beta positive cells do not always express S100 alpha alpha beta beta; and ( 4) the S100 beta expression in light cells, the abundant Na+-K+ ATPase on dark cells of the TV, and previously demonstrated co-localization of S100 beta/GABA in sensory cells suggest that S100 beta could have, in the inner ear, a dual neurotrophic-ionic modulating function.