Brownish gray regions of the brain and spinal cord that contain the neuronal cell bodies.
Based on distinction by the naked eye, the central nervous system (CNS) can be divided into two parts known as white matter and gray matter. These regions were first distinguished by Thomas Willis in his Anatomy of the Brainpublished in 1664. The white matter contains high levels of lipid and thus appears white contrasting with a brownish gray hue commonly associated with the gray matter. The gray matter is formed by the cortex and nuclei of the brain, the horns of the spinal cord, and the ganglia. These regions are heavily populated by dense neuronal cell bodies and numerous capillaries and associated blood cells. Together, the cell bodies and the capillaries are responsible for the darker, grayish color. In addition to the neuronal cell bodies and the endothelial cells of the capillaries, the gray matter also contains...