A Modified Procedure for Lead Staining of Thin Sections

sections for electron microscopy has become the accepted practice in recent years. Salts of metals of high atomic weight such as uranium, chromium, thorium, lead, or tungsten, among many tested, have been found suitable (6, 1). "Lead hydroxide," as preparted by Watson (6), is now widely used, hut this solution is extremely unstable in air and becomes covered by a metallic-appearing film which imparts to the "stained " section a well known deposit of electron-opaque particles and crystals, reducing considerably the percentage of clean areas suitable for micrography (Fig. l). Several procedures and devices have been described to lessen these contaminations. Peachey (5), using lead hydroxide, or subacetate, found