Cerebral cortex nerves. Light micrograph of a longitudinal section through nerves in an area of cerebral cortex. This region of the brain is composed of grey matter. Grey matter contains nerve cell (neurone) bodies (not seen) and their associated processes (dark red lines). The axons are long processes that carry impulses away from the cell body. Dendrites are highly branched processes that carry impulses to the neurone cell body. There are believed to be about 15 thousand million neurones in the cerebral cortex. This region of the brain has essential roles in memory, thought, mental ability and intellect. Magnification unknown.