The Golgi technique selectively impregnates single neurons with silver chromate. Modifications of the technique can be used to show up many independent neurons in each brain. It has provided indispensable information about the way in which sets of neuronal elements contribute to the gross structure of neuropils and tracts.
Impregnations show up as black, purple or reddish brown against a pale yellow background.
The Golgi method is essentially a stochastic technique, the exact chemical mechanism of which remains unclear. Staining method Golgi impregnations were carried out as follows. Cuticle between the compound eyes and at the frons, between the antennae, was removed taking care to duplicate this as exactly as possible between individuals. Blocks were subsequently treated by one of two methods. Each image was scanned at 200 dpi, using a 40x or 100x oil-immersion planapochromat objective with either 1x or 0.6x intermediate magnification.