[Electron-dense deposits in membranous nephropathy: mode and site of the deposit]

Some facts were established, with the electron microscopic studies on punch biopsy material from patients with idiopathic membranous nephropathy, that cannot be explained by Karnowsky theory about the two filters of glomerular capillary wall--rough basal membrane and fine podocyte. Those facts are: I. Multilayer, one upon the other, build up of dense material; 2. Finding of fresh dense material upon the repeatedly thickened basal membranes with their filtration ability being preserved is hard to believe. The pathological alterations described in membranous nephropathy could have their explanation if proceeding from Farquhar theory (Caulifield and Farquhar, 1974; Farquhar, 1975) about the basal membrane as the only filter of glomerular capillary wall and the epithelial cell--as monitor. The antigen-antibody complexes formed and dissolved in blood are filtered through the capillary basal membrane, hance penetrating into the glomerular space. There they are taken up by podocyte and returned, being deposited at the site of attachment of its own podocyte pedicle. The spikes are formed by the withdrawing adjacent pedicle, originating from another neighbouring podocyte. The facts described about glomerular pathology are not only properly explained by the theory of the single filter of glomerular capillary and its monitor but are a proof of M. Farquhar theory as well.