Scanning and Transmission Electron Microscopy

The three-dimensional ultrastructure of mouse glomeruli were studied by scanning electron microscopy using standard protocol. Briefly, kidney cortex was cut into small pieces and fixed with 2.5% glutaraldehyde followed by 1% osmium tetroxide. Samples were dehydrated in a graded series of ethanol (to 100%) and critical point dried. The specimens were freeze-fractured, and sputter coated with platinum. Samples were observed and recorded in a JSM-7600F (JEOL) scanning electron microscope. For TEM examination, specimens were series dehydrated and embedded into epoxy resin according to routine procedures. Ultrathin sections were stained with 2% uranyl acetate and 1% lead citrate. Sections were viewed and recorded using a JEM-1400 plus microscope. Foot process width was measured under 15,000x magnification. Five glomeruli were randomly selected in each mouse, and the width of 50 continuous foot processes were then measured to get an average number of each glomeruli.