The 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 2/28/2019
Updated by: Alireza Minagar, MD, MBA, Professor, Department of Neurology, LSU Health Sciences Center, Shreveport, LA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.