Polymerization of Tau in the presence of 3-APS. Fibrillar Tau polymers assembled in the presence of 3-APS were observed by Electron Microscopy. Mainly, short fibrillar and occasionally longer and wider filaments (inset) were found (A). These polymers are not identical to those found in the presence of heparin (B). An increase in both types was found in the presence of both heparin and 3-APS (C). Bars indicate 0.2 μm. 3-APS induced tau polymerization stained with Th-S and visualized by immunofluorescence (see methods) (D).