HISTOCHEMICAL DEMONSTRATION OF UNSATURATED LIPIDS BY A BROMINE-SILVER METHOD

Abstract

A new method for the histochemical demonstration of unsaturated lipids having a sounder chemical basis than previously reported methods has been developed. Formalin fixed frozen sections are treated with aqueous KBr₃; silver bromide is precipitated at the site of bromination by treatment with silver nitrate in dilute nitric acid; free silver is then formed by reduction with a photographic developer. Specificity is shown by the abolition of staining following any of these control reactions: a) elimination of the bromination step; b) prior blockade of double bonds with performic acid; c) extraction of lipids with chloroform-methanol or d) extraction of silver bromide before development with thiosulfate or cyanide solutions. In addition to normal tissues, atherosclerotic tissues and sections of central nervous tissues exhibiting lipid dystrophies have been examined. This technique has been fully demonstrated on pure compounds deposited on filter paper. Hydrogenated or performic acid treated compounds give negative results.