The gross anatomy of the central nervous system—the brain and spinal cord—was studied in some detail during the seventeenth and eighteenth centuries, but not until the nineteenth century did scientists begin to appreciate that the central nervous system (CNS) was composed of many millions of separate cells, the neurons (also called nerve cells). This discovery had to await technical improvements in the microscope and the development of specialized stains that permitted scientists to observe the microscopic anatomy of the nervous system.

History

In the 1870s, the Italian anatomist Camillo Golgi developed such a special staining technique, and he and other scientists were then able to observe, under the microscope, the fine structures of the cells of the nervous system. Yet Golgi may not have fully appreciated that what seemed to be an extended network of nerve tissue, in reality, were millions of distinct neurons with fine...