Transmission Electron Microscopy of Kidney

Conventional TEM was performed as described previously (Ichimura et al., 2009 (link), 2010 (link)). In brief, the slices of fixed kidney cortex were successively immersed in 0.4% osmium tetroxide (OsO₄) in 0.1 M PB for 1 h, 2% low-molecular-weight tannic acid (LMW-TA, Electron Microscopy Sciences, Hatfield, PA, United States) in 0.05 M maleate buffer for 4 h, and 1% uranyl acetate in 0.05 M maleate buffer for 3 h. The slices were then dehydrated with a graded series of ethanol and embedded in Oken Epok 812 epoxy resin (Oken-shoji, Tokyo, Japan). Ultrathin sections (90–100 nm thickness) were produced with an ultra 45° diamond knife (Diatome, Biel, Switzerland) and transferred to 50-mesh copper grids coated with a Formvar membrane. The ultrathin sections stained with lead citrate and uranyl acetate were digitally photographed with an H-7100 transmission electron microscope (Hitachi High-Technologies, Tokyo, Japan), which was equipped with a C4742-95 CCD camera (Hamamatsu Photonics, Shizuoka, Japan).