The biologist

The shapes of the dendritic arborization of vertebrate neurons is a unique property which differentiates the nervous tissue from all the other tissues of the organism. The neuron doctrine, which we owe to Santiago Ramón y Cajal (Ramón y Cajal, 1904, 1911),was established 50 years after the cellular theory proposed by Schwann in 1839. This long period of trial and error and of vigourous opposition by the adherents of the reticularism is simply explained by the great difficulty of recognizing a nerve cell on histological preparations (Figure 1.1).

It was only after the discovery of the Golgi method, which is a selective technique for visualizing nerve cells and their prolongations that Ramón y Cajal established the first fundamental concept of neuroscience:

He called the nervous tissue the most intricate structure known in the living world. He observed a great number of neurons stained with the Golgi method in a variety of species. The comparison of dendritic morphologies of neurons located in homologous regions of the brains of different animals led him to formulate what we call the ‘shape hypothesis’. It was in the darwinism context of the time and tuned with the comparative phylogenetic approach.