The first staining methods applied to the nervous tissue ocurred in the second half of the XIXth century.
It happened in the hands of Joseph von Gerlach, but it was Otto Deiters, a renown german neuroanatomist, the one who improved the tecnique and was able to provide the most detailed and exhaustive description of a nerve cell known to exist at the time.
He was able to visualize the dendrites and the axon for the first time. But his effort wasn’t enough to give the push that was needed to advance further, because it was impossible to make visible the thin extremities of neurons in their full form. Microscopes wouldn’t give out a clear pattern of the nervous tissue, like it did with other types of tissue.
This push came thanks to Camilo Golgi, the famous Nobel laurate, that lend his name to the cell organelle.
In 1883, Camilo Golgi, discovered a staining method that made much easier the distinction of the individual nervous cells. The “reazione nera” as he called it, or golgi’s staining as we know it.
This technique stains less than 1% of the cells, but it stains them completely. Dendrits and cell bodies are marked in visible black and brown. This is possible when the nervous tissue is impregnated with dichromate potassium and silver nitrate. The microcristalization of silver dichromate makes the cell filled and visible.
This provided a very clear and detailed image of the nervous cells individually, making possible to track the length and trajectory of the dendrites, showing the conexions between neurons and the complex structure of different regions in the brain and spinal cord.
This amazing new view of the brain was well received by Santiago Ramón y Cajal who expressed his awe in the following words:
“Against a clear background stood black threadlets, some slender andsmooth, some thick and thorny in a pattern punctuated by small dense spots. Allwas sharp as a sketch with Chinese ink on transparent Japanese paper. And tothink that this was the same tissue which, when stained with carmine or logwoodleft the eye in a tangled thicket where sight may stare and grope everfruitlessly, baffled in its efforts to unravel confusion, and lost forever intwilit doubt. Here, on the contrary, all was clear and plain as a diagram. Alook was enough. Dumbfounded, I could not take my eyes from the microscope.”
This new neuronal landscape was interpreted very differently by these two brilliant scientists.
In one hand, the staining creator, supported the reticular theory.
In his own words:
“Nerve cells, instead of working individually, act together, so that we must think that several groups of elements exercise acumulative effect on the peripheral organs through whole bundles of fibres. It is understood that this concept implies another regarding the opposite action of sensory functions.”
“However opposed it may seem to the popular tendency to individualize the elements, I cannot abandon the idea of a unitary action of the nervous system, without bothering if, by that, I approach old conceptions.”
On the other hand, Cajal, intuitively considered that nervous cells were discrete units. He introduced, the “proplasmatic kisses”, currently known as synapses, to solve the problem of communication between cells.
He observed that in concrete regions, the population of cells had the same morphological characteristics. The similarity and isolation of the cells, didn’t go well with the idea of a continuum, a reticular net, with no separation between entities.
The neuron doctrine, supported by Cajal, was popularized and named by Heinrich Wilhelm Gottfried von Waldeyer-Hartz, who coined the name neuron to refer to the nerve cell.
In 1906, after just 5 years of the creation of the Nobel prize, both Camilo Golgi and Santiago Ramón y Cajal, received this award in the field of physiology or medicine.
In 1950, the creation of the electronic microscope made posible the demonstration of the neuronal theory, showing that the majority of the nervous cells connect to each other by synapsis. However, that is for the biggest part of them, other little part, does act as Golgi predicted, by open and direct contact (gap junctions). But the neuronal doctrine was accepted, and is now one of the fundamental pillars of Neuroscience.
The neuron doctrine means that the brain and spinal cord are made up of individual elements, called neurons, and their supporting structures. Neurons may touch one another, but they do not fuse.
Golgi provided the method and Cajal obtained new and penetrating insights into the structure of the brain and spinal cord.
As science and art, that they both new how to combine, these two scientist indirectly collaborated and contributed to the establishment of Modern Neuroscience.
The discovery of the organization of the nervous tissue, that was summarized in the Neuron doctrine proposed by Cajal, is one of the fundamental pillars of Modern Neuroscience.