Fig. 6. Stage-dependent effects of Nkx6.1 overexpression on Olig2, Mnr2/Hb9 and Sox10 gene expression. Spinal cord tissues from E2 chicken embryos were electroporated with RCASBP-Nkx6.1 retroviral expression vector, and then were processed either two days (at E4, A-D) or four days (at E6, E-H) later for gene expression studies by immunofluorescence with anti-Nkx6.1, anti-Olig2, anti-Mnr2/Hb9 antibodies or by in situ RNA hybridization with Sox10 riboprobe. Nkx6.1 overexpression induced Olig2 expression at E4 (A), but inhibited its expression at E6 (E). The endogenous expression of Nkx6.1 in the ventral neuroepithelium was much weaker than the retrovirally mediated expression and was not shown under this specific photographic condition. Induction of gene expression is indicated by arrows, whereas inhibition by arrowhead. Note that sporadic expression of Nkx6.1 was also observed in the control side of the spinal cord (E), likely due to the secondary infection of the Nkx6.1-expressing retroviruses produced by the electroporated side.