Portion of the brain and spinal cord consisting mainly of myelinated axons (see myelination) and glial cells.
Note: Neurons of the white matter transmit signals between areas of
grey matter within the cerebrum, to lower brain centers, and up and down the superficial aspect of the spinal cord.
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 821 (https://doi.org/10.1515/pac-2015-1202)