Golgi-like demonstration of "dark" neurons with an argyrophil III method for experimental neuropathology

A silver method is proposed for the selective, well-contrasted and reproducible demonstration of "dark" neurons in frozen, vibratome and paraffin sections cut at a thickness of 5 to 200 microns from aldehyde-fixed brains. The Golgi-like staining of the dendrites enables assorting of "dark" neurons according to characteristic neuron classifications. The staining procedure includes an esterification with 1-propanol, a treatment with diluted acetic acid and development. The esterification strongly increases the argyrophilia of both "dark" neurons and mitochondria. Unwanted co-staining of mitochondria is suppressed by the acetic acid treatment, while a special developer is used to render the staining controllable. The applicability of the method to experimental neuropathology is demonstrated by Golgi-like staining of "dark" neurons in rat brains exposed, before transcardial perfusion-fixation and delayed autopsy, to various pathological conditions including ischemia, hypoglycemia, trauma, status epilepticus, deafferentation and poisoning with kainic acid, colchicine and sodium azide, respectively.