Anionic sites of the basement membrane of the labyrinth.

The presence of anionic sites in the labyrinth is demonstrated in this study, using polyethyleneimine as a cationic probe. Hartley-strain guinea pigs (200-300 g) with a normal Preyer's reflex were used. A 0.5% polyethyleneimine (PEI, MW 1,800) solution adjusted to pH 7.3 with HCl following Schurer's method was systemically administered through an axillary vein. In the cochlea, the presence of anionic sites was demonstrated on the basement membrane of the capillary wall in the stria vascularis. The presence of anionic sites was also confirmed on the basement membrane in Reissner's membrane but its density was much lower than that in the stria vascularis. In the ampulla and macula, the anionic sites were present on the basement membrane of the capillary wall and sensory epithelium.