The central nervous system is comprised of grey matter and white matter. Grey matter contains cell bodies, dendrites and axon terminals of neural cells. White matter contains all of the axons of the neural cells. These axons connect the grey and white matter together.
Grey matter is also different from white matter in that it contains very few myelinated axons. The myelination of the axons is what gives the white matter its color. The cell bodies appear grey and give the grey matter its color. In living tissue samples, grey matter may also appear yellow with pink hues due to blood vessels present in the matter, but in dead tissue samples the matter is grey.