2 methods have so far been proposed for staining samples by the argyrophil technique of Grimelius for electron microscopy. Vassallo et al. (1971) used en bloc staining after fixation with a mixture of glutaraldehyde and formaldehyde, then Håkanson et al. (1971) stained sections from samples previously fixed by double formaldehyde/OsO4 treatment and embedding in resin. Another investigation that concerned glutaraldehyde fixation showed the effect of this fixative in sample staining (Soranzo and Roland 1987). The present experiments demonstrated that Epon intervenes directly in argyrophil staining of sections. With this resin, the staining process lasted longer than with paraffin embedding materials and offered no guarantee of positivity. Granules with a double structure and dense core displayed different locality of argyrophilia before and after embedding.