BRANCHING BEAUTIES: Ramón y Cajal used Camillo Golgi’s stain to visualize the fine-scale morphology of neurons in several areas of the brain. In this stunningly detailed illustration of a Purkinje cell in the human cerebellum, Cajal depicts the neuron’s famously thick forest of dendrites (c and d) branching off one side of the nerve cell body, the axon (a), and the collateral axon (b), which loops back to connect with the dendrites or cell body. Cajal’s remarkable ability to visualize serial sections was key to his proposal that gaps, later called synapses, separate individual neurons. CAJAL LEGACY. INSTITUTO CAJAL (CSIC), MADRID (SPAIN)In 1887, a young Spanish anatomist by the name of Santiago Ramón y Cajal visited Luis Simarro Lacabra, a colleague in Madrid who had recently returned from Paris with sections of brain tissue treated with an obscure staining technique. Developed 14 years earlier by the Italian physician Camillo Golgi, the stain—which Golgi dubbed la reazione nera, or “the black reaction”—was produced by soaking blocks of preserved tissue in a silver nitrate solution. This gave anatomists the most detailed visualizations yet of the morphological features of entire nerve cells, from the tips of dendritic branches to the tapering ends of axons.
Cajal used the technique to produce the exquisitely detailed illustrations of brain cells that later formed the basis for his “neuron doctrine,” which stated that the neuron is the basic anatomical and physiological unit of the nervous system. The work earned Cajal the 1906 Nobel Prize in Physiology or Medicine, which he shared with Golgi despite their almost complete lack of agreement about the basic structure of the nervous system.
This debate had split the burgeoning field of neuroscience for most of the 19th century. One camp—the reticulists, led by Golgi—thought the nervous system consisted of a diffuse network of continuous tissue, or reticulum, formed by the fused branches of dendrites and axons. The other camp—the neuronists—countered that the nervous system was composed of distinct ...
