Bielchowsky stained cerebellum. Image courtesy of Wikimedia Commons.
The Bielschowsky silver protocol is used to stain neuronal cell bodies and processes. Tissue sections are treated with silver nitrate and ammoniacal silver nitrate solutions. Silver is deposited on the neurofibrillary tangles and axonal or dendritic processes of senile plaques. The silver is then reduced to metallic silver with formalin. Unreduced silver is removed with sodium thiosulfate.