The Periodic Schiff-Methenamine (PASM) staining of renal biopsies-A light and electron microscopic study.

Methods for Periodic Schiff-Methenamine Silver (PASM) staining of human kidney glomerular basement membranes in epoxy resin-embedded one μm thick sections were investigated. Removal of the resin prior to staining gave better resolution of cytological detail than sections which were still embedded in the resin. Various methods for the fixation of renal biopsies were compared; osmium tetroxide fixation produced the best visual differentiation of the glomerular basement membrane as a distinct entity from the deposits adjacent to it. Electron microscopic examination of PASM stained glomeruli supported this conclusion.