Role of radial glial cells in cerebral cortex folding

•Gyrification is wide-spread in all mammalian lineages.•The program for gyrification can be elicited in mice with a lissencephalic cortex.•Amplification of several types of radial glia is critical for folding/gyrification.•Trnp1 is a critical regulator of amplifying these different types of radial glia.•Temporal and spatial regulations of such regulators are key to these processes.

Radial glial cells play key roles during cerebral cortex development, as primary stem and progenitor cells giving rise - directly or indirectly - to neurons and glia, but also acting as scaffold for the cerebral cortex architecture and migrating neurons. Recent work led to the discovery of novel types of radial glial cells with key roles in gyrification, the folding of the mammalian cerebral cortex in phylogeny and ontogeny. Here we summarize the cellular and molecular basis of this fascinating process allowing the expansion of the mammalian cerebral cortex with all its functional consequences.