When stained, they show regions of white matter and regions of grey matter, the white is composed of myelinated axons and the myelin producing oligodendrocytes (Junqueira and Carneiro, 2005). The grey matter contains neuronal cell bodies, dendrites and the unmyelinated portions of the axons and glial cells. The grey matter is prevalent at the surface of the cerebrum and the cerebellum, as compared to the white matter which is present in more central regions (Junqueira and Carneiro, 2005).
In the cerebral cortex, the grey matter has six layers of cells of all different forms and sizes. There are both sensory neurons and motor neurons in the different regions of the cerebral cortex which control voluntary movements. The cells of the cerebral cortex have functions related to the integration of sensory information and the initiation of voluntary motor responses, see figure 1-7(Junqueira and Carneiro, 2005).
Figure 1-8 Silver-stained section of cerebral cortex showing many pyrimad-shaped neurons with their processes and a few glial cells. Medium magnification (Junqueira and Carneiro, 2005)There are three layers of the cerebellum: a molecular layer, a Purkinje layer and a granular layer.The molecular layer is the outermost layer, it cells are less dense than those in the granular layer, it also has the dendrites of the Purkinje cells that occupy the Purkinje layer. The Purkinje layer composed of large Purkinje cells, these have a conspicuous cell body and have highly developed dendrites. The Granular layer is the inner layer, it is formed by small neurons which are very compacted together (Junqueira and Carneiro, 2005). The cerebellum and its layers can be seen in figures 1-8 and 1-9.
Figure 1-9 Section of the cerebellum with dintinct Purkinje cells. H&E stain. Medium magnification. (Junqueira and Carneiro, 2005).
The Spinal cord has white matter on the outside and grey matter on the inside usually forming an 
H shape and has large and multipolar neurons The horizontal bar in the H of the grey matter forms the central canal, the legs of the H form the anterior horns and the arms of the H form the anterior horns.The central canal is remnat of the luman of the embryonic neural tube and the anterior horns have the motor neurons whose axons make up the ventral roots of spinal nerves, the anterior horns receive sensory fibers from neurons in the spinal ganglia (Junqueira and Carneiro, 2005). A cross section of the spinal cord can be seen in figure 1-10.
The skull and the vertebral column protect the central nervous system, but they are aided by a membrane of connective tissue called meninges. The meninges are the dura matter, arachnoid and pia matter. Dura matter is the external layer and is composed of dense connective tissue with the periosteum of the skull. The arachnoid has two compartments: a layer that connects with the dura matter and a layer of trabeculae connecting to the pia matter. The Pia matter is loose connective tissue that contains the blood vessels (Junqueira and Carneiro).
