Light and electron microscopic localization of silver in biological tissue

A method is described that visualizes trace amounts of silver in frozen, paraffin and epon sections from biological tissue. After exposure to light, which ensures reduction of silver ions that are not bound to sulphide, histological sections from animals treated with silver compounds are exposed to a photographic developer containing silver ions. Tissue silver acts as a catalyst for the hydroquinone reduction of silver ions to metallic silver which then accumulates at the site of the trace deposit. Light and electron micrographs showing silver in different organs from albino rats treated with silver lactate are presented. Localization of silver in motor neurons of the spinal gray matter and pons indicates a transport of silver over the blood-brain barrier. Silver precipitates in fetal liver suggest that silver ions can penetrate the placental barrier.