Fig. 6. Tracer-permeability assay of the stria vascularis of 10-week-old Cld11^+/+ and Cld11^-/- mice. An isotonic solution containing freshly made biotinylation reagent was injected into the perilymph space from the round window of the cochlea and, after a 5 minute incubation followed by washing with PBS, the cochlea was dissected out, fixed and frozen. Frozen sections were double stained with anti-E-cadherin pAb (red) and streptavidin (green) to detect cell layers and bound biotin, respectively. In the Cld11^+/+ stria vascularis, the biotinylation reagent diffused freely through the connective tissue, represented as `compartment III' in Fig. 1B, but did not get into the intrastrial space (`compartment II' in Fig. 1B). In sharp contrast to this, in the Cld11^-/- cochlea, diffusion of the biotinylation reagent was not stopped at the basal cell layers but the reagent appeared to pass through them to reach the intrastrial space. Yellow and pink arrowheads represent the marginal and basal cell layers, respectively. Bar, 20 µm.