Radial glial cells

Radial glial cells are a pivotal cell type in the developing central nervous system (CNS) involved in key developmental processes, from patterning and neuronal migration to their recently discovered role as precursors during neurogenesis. They arise early in development from neuroepithelial cells. Radial phenotype is typically transient, but some cells, such as Bergmann glia in the cerebellum and Muller glia in the retina, retain radial glia-like morphology postnatally. According to recent research, during the late stages of cortical development, radial glial cells divide asymmetrically in the ventricular zone to generate radial glial cells, postmitotic neurons and intermediate progenitor cells. Intermediate progenitor cells then divide symmetrically in the subventricular zone to generate neurons. During gliogenesis, radial glial cells differentiate into astrocytes.

The term 'radial glial cell' refers to their two major characteristics, their long radial processes extending from the ventricular zone (VZ) to the pial surface and their glial properties, such as the content of glycogen granules or the expression of the astrocyte-specific glutamate transporter or the glial fibrillary acidic protein (GFAP). Another radial glia-specific protein is the brain lipid binding protein (FABP7), expression of which could be induced by Notch-1 activation, in particular, when acted upon by reelin. Interestingly, Notch 1, then activated before birth, induces radial glia differentiation, but postnatally induces the differentiation into astrocytes.

Studies show that radial glial cells characterized by long radial processes and astroglial properties constitute the majority of precursors during neurogenesis. Indeed, all radial glial cells divide throughout neurogenesis and give rise to the majority of projection neurons in the cerebral cortex.

Expression of the PAX6, a transcription factor, was found to be the key feature of neurogenic radial glia.

Fgf10 has been shown to regulate the differentiation of radial glia from norepithelial cells.