OverviewThe tissue called "gray matter" in the brain and spinal cord is also known as substantia grisea, and is made up of cell bodies. "White matter", or substantia alba, is composed of nerve fibers.
Review Date 1/26/2017
Updated by: Linda J. Vorvick, MD, Clinical Associate Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.