The Use of Vanadium as a Stain for Electron Microscopy

Utilization of heavy metals in electron microscopy to obtain image contrast of a degree greater than that resulting from fixation with osmium tetroxide or potassium permanganate is now an accepted practice. Staining is virtually essential when an epoxy resin is used as embedding medium, but only a small number of compounds have been suggested and few of these are in routine use. Lead hydroxide (21), one of the more effective stains, is probably the most widely employed in laboratories working with biological material. A number of modifications of this stain have been introduced, however, attesting to the difficulties encountered in obtaining preparations free of lead carbonate precipitate. Several mechanical devices have been proposed (6, 9, 15, 16), and chemical alterations