Regional specification of neurosphere cultures derived from subregions of the embryonic telencephalon.

We have studied the molecular specification of precursor cells in expanded neurosphere cultures derived from distinct subregions of the embryonic mouse telencephalon. These regionally derived cultures exhibited differential responses to the mitogens EGF and bFGF, suggesting that the precursors in these cultures were differentially specified as is the case in situ. To examine this further, cultures from each of the telencephalic subregions were expanded in both EGF and bFGF before differentiation. The neurons produced displayed molecular phenotypes similar to those normally derived from each of these regions in vivo. Moreover, analysis of gene expression in the undifferentiated cultures showed that the regionally derived neurospheres express many of the same developmental control genes as their in vivo counterparts. Taken together, the present findings suggest that precursor cells in neurosphere cultures, derived from distinct subregions of the embryonic telencephalon, maintain at least certain aspects of their molecular specification, even after significant expansion in vitro.