An increase in cell cycle length, specifically G1 phase, is naturally associated with the progression of neurogenesis. A recent model, referred to as 'cell cycle length hypothesis', has been proposed, largely on the basis of the observation that lengthening the neuroepitehlial cel cycle alone is sufficient to promote the transition from symmetric proliferative to asymmetric neurogenic divisions.

This hypothesis emphasizes that unequal inheritance of a cell fate determinant

by daughter cells may or may not lead to distinct fate specification. Instead, the length of cell cycle determines the time window in which the cell fate determinant is allowed to act, thereby resulting in fate specification.

Reviewed by Xin Tan and Song-Hai Shi, WIREs Dev Biol 2012. doi: 10.1002/wdev.88