The Function and Lectin Receptors in the Guinea Pig Stria Vascularis

Abstract

Soybean agglutinin (SBA), helix pomatia agglutinin (HPA), ricinus communis agglutinin-11 (RCA-II), limax flavus agglutinin (LFA) and wheat germ agglutinin (WGA) were employed to localize, with a lectin-gold technique, specific carbohydrates on thin sections of guinea pig stria vascularis embedded in Lowicryl K4M.
Galactose and N-acetylgalactosamine labeled with SBA, HPA and RCA-II were found in many cyto-plasmic vesicles and endosomes located in the supra-nuclear region, as well as in the microvilli and in the plasma membranes of internalization of marginal cells.
LFA labeling, indicating the distribution of sialic acid residues, was found in the basement membrane of the perivascular spaces and intercellular spaces between marginal and intermediate cells and between marginal and basal cells. Plasma membrances, how-ever, were unlabeled in all types of cells.
WGA binding sites showing the localization of N-acetylgalactosamine, on the other hand, were detected along the plasma membranes of all types of cells constituting the stria vascularis and in some supranu-clear cytoplasmic vesicles in marginal cells.
These findings revealed that the membranes of internalization and some cytoplasmic vesicles were as-sociated with endosomes in the supranuclear region of the marginal cells. It is probable that these struc-tures are related to the functions of absorption and secretion, and that the carbohydrates labeled with SBA, HPA and RCA-11 are recirculated in this system, the exchange between Na+ and K+ facilitating.