The two main anatomical components found in the central nervous system are nuclei and the axonal tracts. The nucleus is the area where neuronal cell bodies that have the same function are grouped together, and send their axons in a bundle or “tract” to their targets. The nuclei in the CNS, where cell bodies are abundant, appear darker, hence are referred to as the gray matter whereas the fiber tracts, paler in appearance due to the myelin around the axon, are called the white matter. However, this difference is not clearly apparent to an untrained eye. In gross neuroanatomical laboratory classes, attempts
have been made to ease this obstacle by way of staining.