Fig. 3. (A) Induction of oligodendrocyte-related genes in isolated mouse E12.5 dorsal and whole E12.5 SHH null cord following FGF2 treatment in the presence or absence of cyclopamine (1 µM). Untreated dorsal wild-type and whole SHH null spinal cord show no Olig2 and Nkx2.2 expression. Following FGF2 expansion, induction of Olig2 and Nkx2.2 is apparent with significant upregulation of Olig1. Ihh message is present in dissociated untreated wild-type cultures and in SHH-null expanded cultures. Significantly, absence of the V3 and pMN genes Nkx2.9 and Nkx6.1 is evident in all conditions. (B) Immunomicrographs showing OLIG2- and NKX2.2-positive cells in dorsal-derived neurospheres grown in the presence of cyclopamine (1 µM), and fixed and stained at 7 days in vitro. Arrow indicates co-positive OLIG2 and NKX2.2 cells.