Periodic submembranous structures at the AIS. A, The AIS imaged by STED microscopy from high-CF (left) and low-CF (right) regions at E15 (top) and P3 (bottom). The AIS was stained with ankyrinG antibody. B, Intensity profile at the box in A. Note that the profile shows periodicity regardless of tonotopic regions and ages. C, Periodic interval of ankyrinG signals. The interval was ∼170 nm in all the conditions. Numbers in parenthesis are the number of AISs. p = 0.9019 among the groups by Kruskal–Wallis test.