Tenascin-R is a protein that in humans is encoded by the TNR gene. Tenascin-R (TNR) is an extracellular matrix protein expressed primarily in the central nervous system. It is a member of the tenascin (TN) gene family, which includes at least 3 genes in mammals: TNC (or hexabrachion), TNX (TNXB), and TNR. The genes are expressed in distinct tissues at different times during embryonic development and are present in adult tissues. TNR has been detected predominantly in the central nervous system and is localized around motor neurons and on motor axons in the spinal cord, cerebellum, hippocampus, and olfactory bulb. It is suggested that tenascin-R has a role in initiating the detachment of neuroblasts from tangential chains and in initiating radial migration of the cells.