Ramón y Cajal worked on thin slices of brain tissue which were laid on microscope slides and stained with silver. The stain was invented by Golgi, who shared the Nobel Prize with him.
Ramón y Cajal's investigations of the microscopic structure of the brain were original: he is considered by many to be the father of modern neuroscience. He was skilled at drawing, and hundreds of his illustrations of brain cells are still used for educational purposes today.[3]
Drawing of the neural circuitry of the rodent hippocampus