A rapid silver impregnation method for nervous tissue: a modified protargol-peroxide technic.
A rapid, reliable silver impregnation method is described for nervous tissue fixed in formol-saline, Bouin or Susa. Sections are impregnated for 10-15 minutes at room temperature or 37 C in a solution containing 0.5 g Protargol-S, 0.005-0.01 g allantoin, 1 ml of 1% Cu[NO3]2, 1 ml of 1% AgNO3, and 1-2 drops of 30% H2O2 in 100 ml distilled water. Thereafter the sections are reduced in a hydroquinone-formalin solution. This is followed by gold toning and subsequent reduction and mounting. Alternatively, following the first reduction, the silver image can be intensified by placing sections in a silver-allantoin bath which is followed by reduction and mounting. This method is very reliable and selective, making it suitable for general routine and research use.