A SENSITIVE POST-DAB ENHANCEMENT TECHNIQUE FOR DEMONSTRATION OF IRON IN THE CENTRAL-NERVOUS-SYSTEM

A technique is described for enhancing the reaction product of the sta ining reaction for iron in paraffin-embedded tissue from central nervo us system (CNS). After amplification of the Prussian Blue staining rea ction with 3,3'-diaminobenzidine (DAB), the reaction product was furth er intensified using a stepwise treatment with silver methenamine, gol d chloride and uranyl nitrate (post-DAB treatment). Following the Prus sian Blue-DAB staining reaction, iron was seen only in glial cells and choroid plexus epithelial cells, whereas the post-DAB treatment revea led that neurons and endothelial cells of the brain capillaries were a lso positively stained. The post-DAB treatment resulted additionally i n an increased intensity of the reaction product within choroid plexus epithelial cells compared to that obtained in sections subjected only to the Prussian Blue-DAB reaction. The reliability of the method was evaluated using liver sections as positive controls. Furthermore the h igher sensitivity of the method was assessed using nitrocellulose filt ers containing serially diluted iron-saturated transferrin. The post-D AB method is simple and can easily be applied to formalin- or glutaral dehyde fixed, paraffin-embedded nervous and non-nervous tissue.