ANIONIC SITES ON REISSNERS MEMBRANE, STRIA VASCULARIS, AND SPIRAL PROMINENCE

We demonstrated anionic sites on the lateral wall of coch;lear duct an d Reissner's membrane (RM) of ICR mice by Lowicryl K4M resin post-embe dding and poly-L-lysine-colloidal gold conjugate (PL-CG) as a polycati onic probe. The basement membrane and endolymphatic cell surface of RM were labeled with PG-CG pH 2.5 and pH 1.0, However, the perilymphatic cell surface was not labeled, PG-CG pH 2.5 and pH 1.0 strongly labele d the endolymphatic surface of the spiral prominence epithelium (SP), whereas the endolymphatic surface of the marginal cell (MC) in the str ia vascularis was not labeled, Pre-digestion with several glycosidases eliminated PL-CG labeling, Our result suggests that an anionic charge located on the basement membrane of RM is largely due to the presence of heparan sulfate, chondroitin sulfate, and hyaluronic acid, An anio nic charge on the endolymphatic cell surface of RM was mainly dependen t on the presence of heparan sulfate, An anionic charge on the SP epit helium was caused to a substantial degree by chondroitin sulfate. We o btained histochemical evidence that the glycoconjugate content of the MC surface was quite different from that of the endolymphatic cell sur face of RM and SP. We also identified RM-MC and SP-MC junctions at the ends of the stria vascularis between the marginal cells and the other endolymphatic epithelial cells of the cochlear duct.