Precursor cell types in the germinal zone of the cerebral cortex

Retroviral lineage tracing experiments suggest that the cortical ventricular zone is composed of a mixture of precursor cell types. The majority generate a single cell type (neurones, astrocytes or oligodendrocytes) and the remainder generate neurones and a single type of glial cell. Pluripotential precursor cells, that have the ability to generate all three cell types, are not observed. A recent paper, however, reports that when single ventricular zone cells are cultured in isolation, a small percentage of these cells are pluripotential (1) . This review will discuss what this knowledge tells us about cortical development.