FIG. 1.

Postnatal proliferative capacity in the cortex is lost by P15. (a,b) Neurospheres derived from postnatal day 8 (P8) hippocampus (a) and cortex (b; scale bar 100 μm). (c) Measurements of average diameters of spheres formed from P8 mice after 5, 8, and 11 days in vitro (DIV; n=3 experiments). There is no difference in the average size of spheres between hippocampus- and cortex- derived cells. (d) The average expansion ratio over nine passages did not differ between proliferating cells from P8 hippocampus or cortex. (e) Whereas neurospheres derived from P15 mouse hippocampus form readily, virtually none form from dissociated cells derived from P15 mouse cortex (n=4 experiments). (f ) Secondary clonal spheres from P8 mice were differentiated and stained for βIII tubulin, glial fibrillary acidic protein (GFAP) and DAPI (scale bar 150μm).