Figure 2: Neural stem cells/neuroblast (NB) undergo two types of self-renewing cell divisions: symmetric (proliferating) and/or asymmetric (differentiating). (a) Type I NB self-renew, and also generates a ganglion mother cell (GMC) which divides only once to generate two postmitotic daughter cells that differentiate into neurons or glial cells [2, 1618]. (b) Type II NB initiates expression of the proneural gene asense and becomes an intermediate neural precursor (INP), which undergoes self-renewing asymmetric divisions, with each division resulting in one INP and one GMC [2226]. Type II NB generates much larger lineages compared to type I NB.