Re: how can AgNO3 dye the neuron?

Toko,

     The method of staining neurons with silver nitrate (AgNO3) was 
developed in 1873 by the Italian scientist Camillo Golgi.  This method is 
often called the Golgi stain and also silver impregnation.  A tissue 
sample is treated with potassium bichromate and then with silver nitrate.  
The silver nitrate stains the surface of some neurons causing them to 
appear dark black.  The silver cation is reduced to neutral silver metal, 
which is jet black.  
     For reasons that are not known, this method thoroughly stains about 
5% of neurons while nearby neurons are completely unaffected.  If all 
neurons were stained, one would only see a mass of black.  The usefulness 
of this stain is its unusual selectivity.  Golgi’s staining method allowed 
him to conduct pioneering work on the study of neuronal structure for 
which he won the Nobel prize in 1906.