Central nervous system consists of White and Grey matter. White matter has myleinated neurons and thus appears white as myelin sheath is white in colour. Grey matter consists of cell bodies of neurons. This is seen in brain and spinal cords but in reverse pattern. In brain the white matter is inside while grey matter forms the cortex. In spinal cord the grey matter is in the centre as H shaped while white matter surrounds it. This is seen in the cross section of spinal cord.