Looking through a microscope, the brain once appeared as an indistinct mass of tangled tissue. Scientists could see cells, but not how individual neurons were organized or connected.
In 1873, Italian physician and scientist Camillo Golgi transformed neuroscience by developing the Black Reaction (la reazione nera), a silver chromate staining technique that randomly stained only a small number of neurons. Because just a few cells were coloured while their neighbours remained transparent, each stained neuron could be seen in its entirety—its cell body, branching dendrites, and long axon. For the first time, researchers could appreciate the extraordinary complexity and diversity of individual neurons.
One laboratory technique opened an entirely new window into the brain’s architecture, laying the foundation for modern neuroscience.
Golgi’s method also enabled Santiago Ramón y Cajal to demonstrate that the brain is composed of individual neurons rather than a continuous network, establishing the neuron doctrine that underpins modern neuroscience.
Last Updated on October 6, 2026 | Published: July 11, 2026