PAS x40 - RCPA

Electron microscopy:• a piece of cortex about 1mm containing at least oneglomerulus is selected and placed in glutaraldehyde• the tissue is processed and embedded in plastic or resin• semi-thin sections are cut with a glass knife• the sections are stained with toluidine blue or similar stain• they are examined by light microscopy and a glomerulusis selected for examination• the block is trimmed to a “mesa” and ultrathin sectionsare cut, stained with lead citrate and uranium acetate• the ultrathin sections are examined in an electronmicroscope and photographed• tissue may also be cut out of the paraffin block andreprocessed; ultrastructural detail is poorer than when thetissue is conventionally processed but deposits can beidentified and basement membrane thickness measured