Staining solution reagent Silver Impregnation

for histologyfor cytology

Minimum number of tests that can be performed 100 Completion time 35 minutes Shelf life 1 year Storage conditions 2-8°C Additional equipment Not required Application The method of choice for viewing argyrophilic reticular fibers of connective tissue. Result Reticular and nerve fibers black Connective tissue brown Collagen yellow Product for the preparation of cyto-histological samples for optical microscopy. Recommended method to show argyrophilic reticular fibres in connective tissue, especially to differentiate collagen fibres from connective tissue. PRINCIPLE This method produces a selective evident impregnation in a very short time thanks to two factors: the preliminary impregnation with an iron salt and the use as silver source of an unstable diaminic complex (ammoniacal solution), which is more reactive than silver nitrate. a) Pre-treatment with trivalent iron. After a preparatory oxidation with potassium permanganate, the section is treated with trivalent iron (ferric ammonium sulphate). Iron ions, more reactive than silver ions, quickly bind affine functional groups in argyrophilic structures. b) Treatment with ammoniacal solution. Silver is present in ammoniacal solution in the form of complex hydrosoluble oxide - [Ag(NH 3) 2] 2O . This complex silver cation replaces iron previously bound to tissues. In the next step, formic aldehyde acts as reducing agent: it removes oxygen from the complex and releases metallic silver that deposits on argyrophilic structures. Unreduced silverdiamine cation is then removed by sodium thiosulfate (Na2S2O3). Both form a complex which is highly soluble but cannot be oxidized any more.