“…However, an alternate explanation appears more probable in INS. Recent studies utilizing ultrastructural tracers have suggested that the glomerular epithelial slit pores may contribute significantly to glomerular permeability characteristics (27)(28)(29)(30). According to this view, there are two barriers to filtration in the glomerulus, the GBM acts only as a coarse filter for relatively large molecules, and the final filtration barrier for smaller molecules is located at or about the level of the epithelial slit pore or diaphragm (4).…”