the corpus callosum is a region of white matter that
Corpus callosum The corpus callosum (/ˈkɔːrpəs kəˈloʊsəm/; Latin for "tough body"), also callosal commissure, is a wide commissure, a flat bundle of commissural fibers, about 10 cm long[citation needed] beneath the cerebral cortex in the brains of placental mammals. It spans part of the longitudinal fissure, connects the left and right cerebral hemispheres, and enables communication between the hemispheres. It is the largest white matter structure in the human brain, consisting of 200–250 million axonal projections.[1]
Grey matter Grey matter (or gray matter) is a major component of the central nervous system, consisting of neuronal cell bodies, neuropil (dendrites and myelinated as well as unmyelinated axons), glial cells (astroglia and oligodendrocytes), synapses, and capillaries. Grey matter is distinguished from white matter, in that it contains numerous cell bodies and relatively few myelinated axons, while white matter contains relatively few cell bodies and is composed chiefly of long-range myelinated axon tracts.[1] The colour difference arises mainly from the whiteness of myelin. In living tissue, grey matter actually has a very light grey colour with yellowish or pinkish hues, which come from capillary blood vessels and neuronal cell bodies.[2]