Biology:Dying neurons with silver nitrate

Method of coloring neurons with silver nitrate (AgNO₃) was discovered in 1873. by the Italian scientist Camillo Golgi. This method is often referred to as Golgi's stain, and also silver impregnation. On the tissue sample a potassium bichromate is added, and then silver nitrate. Stains of silver nitrate around the surfaces of neurons causes them to appear darker. Silver cation is reduced to neutral element of silver, which has the jet black color.

This method thoroughly stains around 5% of neurons, while surrounding neurons are completely unaffected. If neurons were all to be colored, only one would be stained in black. Usefulness of this coloring is in its unusual selectivity. Golgi's method of staining allowed him to conduct experiments in the field of study of neuronal structure, for which he was awarded with the Nobel prize in 1906.