Timing of CNS cell generation: A programmed sequence of neuron and glial cell production from isolated murine cortical stem cells

Multipotent stem cells that generate both neurons and glia are widespread c omponents of the early neuroepithelium. During CNS development, neurogenesi s largely precedes gliogenesis: how is this timing achieved? Using clonal c ell culture combined with long-term time-lapse video microscopy, we show th at isolated stem cells from the embryonic mouse cerebral cortex exhibit a d istinct order of cell-type production: neuroblasts first and glioblasts lat er. This is accompanied by changes in their capacity to make neurons versus glia and in their response to the mitogen EGF. Hence, multipotent stem cel ls alter their properties over time and undergo distinct phases of developm ent that play a key role in scheduling production of diverse CNS cells.