Radial glia diversity: a matter of cell fate.

Early in development of the central nervous system, radial glial cells arise from the neuroepithelial cells lining the ventricles around the time that neurons begin to appear. The transition of neuroepithelial cells to radial glia is accompanied by a series of structural and functional changes, including the appearance of "glial" features, as well as the appearance of new signaling molecules and junctional proteins. However, not all radial glia are alike. Radial glial lineages appear to be heterogeneous both within and across different brain regions. Subtypes of neurogenic radial glia within the cortex, for example, may have restricted potential in terms of the cell types they are able to generate. Radial glia located in different brain regions also differ in their expression of growth factors, a diverse number of transcription factors, and the cell types they generate, suggesting that they are involved in regionalization of the developing nervous system in several aspects. These findings highlight the important but complex role of radial glia as participants in key steps of brain development.