bHLH family proteins control the timing and completion of transition from neuroepithelial cells into neural stem cells.

The number of neural stem cells reflects the total number of neurons in the mature brain. As neural stem cells arise from neuroepithelial cells, the neuroepithelial cell population must be expanded to secure a sufficient number of neural stem cells. However, molecular mechanisms that regulate timely differentiation from neuroepithelial to neural stem cells are largely unclear.