Neuron theory was advanced through tireless promotion of Cajal’s stained brain sections, in which distinct neuron boundaries were clearly visible. Cajal was able to detect the delicate structure of neurons by applying Golgi’s silver nitrate staining method to samples from embryological or perinatal tissue, in which the neurons were unmyelinated and thus more easily susceptible to staining.

This section of the cerebral cortex from a human infant is an excellent example of the success of his technique. Though their processes overlap, the cells are clearly distinct from one another. By noting the placement of the axons and dendrites, Cajal was also able to postulate the direction in which information flows through this tissue—from the deeper layers of the cortex up toward the surface. 

The precentral gyrus is now known to be part of the primary motor cortex, which coordinates with several other parts of the brain to plan and execute muscle movements.

This plate was created for an exhibit in the Porter Neuroscience Building at the NIH and is being provided here, courtesy of the Cajal Institute (Neuroscience Research Center of the Spanish Main Research Council) Producido con el permiso de El Instituto Cajal (IC), Consejo Superior de Investigaciones Científicas (CSIC).  As such, it's being shared under a creative commons license, so that reuse of the materials are attributed to the museum.

This plate was created for an exhibit in the Porter Neuroscience Building at the NIH and is being provided here, courtesy of the Cajal Institute (Neuroscience Research Center of the Spanish Main Research Council) Producido con el permiso de El Instituto Cajal (IC), Consejo Superior de Investigaciones Científicas (CSIC).  As such, it's being shared under a creative commons license, so that reuse of the materials are attributed to the museum.