Grey substance is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil, glial cells, synapses, and capillaries. Grey substance is distinguished from white matter, in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively very few cell bodies and is composed chiefly of long-range myelinated axon tracts. The colour difference arises mainly from the whiteness of myelin. In living tissue, grey substance actually has a very light grey colour with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.
Grey substance refers to unmyelinated neurons and other cells of the central nervous system. It is present in the brain, brainstem and cerebellum, and present throughout the spinal cord.
Grey substance is distributed at the surface of the cerebral hemispheres and of the cerebellum, as well as in the depths of the cerebrum, cerebellar, brainstem.
Grey substance in the spinal cord is known as the grey column which travels down the spinal cord distributed in three grey columns that are presented in an "H" shape. The forward-facing column is the anterior grey column, the rear-facing one is the posterior grey column and the interlinking one is the lateral grey column. The grey substance on the left and right side is connected by the gray commissure. The grey substance in the spinal cord consists of interneurons, as well as cell bodies.