White matter

White matter refers to areas of the central nervous system (CNS) that are mainly made up of myelinated axons, through which messages pass.

central nervous system (CNS) - One of the two parts of the human nervous system, the other part being the peripheral nervous system. The central nervous system consists of the brain and spinal cord, while the peripheral nervous system consists of nerves that travel from the central nervous system into the various organs and tissues of the body.

mastocytosis A type of mast cell disease in which chronic symptoms are related to overproduction or over-accumulation of mast cells. Not to be confused with Mast Cell Activation Syndrome (MCAS), where there are normal numbers of mast cells, but abnormal activity.