Radial glial cell the onset of gliogenesis, it is unclear whether they are involved in spinal cord neurogenesis or migration. Radial glia have also been implicated in forming boundaries between different axonal tracts and white matter areas of the brain. As radial glia serve as the primary neural and glial progenitors in the brain, as well as being crucial for proper neuronal migration, defects in radial glial function can have profound effects in the development of the nervous system. Mutations in either Lis1 or Nde1, essential proteins for radial glial differentiation and stabilization, cause the associated neurodevelopmental diseases Lissencephaly and micro-lissencephaly (which literally
Glial scar molecules that chemically prevent axonal extensions. Moreover, the basal membrane component is expected to generate an additional physical and chemical barrier to axonal extensions. The formation of the glial scar is a complex process. Several main classes of molecular mediators of gliosis have been identified and are briefly discussed below. Two neuronally-important subclasses of transforming growth factor family of molecules are TGFβ-1 and TGFβ-2 that directly stimulate astrocytes, endothelial cells, and macrophages. TGFβ-1 has been observed to increase immediately after injury to the central nervous system, whereas TGFβ-2 expression occurs more slowly near the injury site. Further, TGFβ-2 has been