<i>ECR9</i> is an OL enhancer in vivo.

(A) Schematic representation of the transgenic constructs consisting of ECR9 in wildtype (ECR9wt) or mutant (ECR9mt) version, the minimal Hsp68 promoter (hsp68), the lacZ marker gene (lacZ) and a SV40 polyA signal (pA). Original Sox binding sites are marked in dark red, inactivated ones in light red. (B) Summary of lacZ expression patterns in ECR9wt-lacZ and ECR9mt-lacZ transgenic animals as determined by X-gal staining and immunohistochemistry on transverse sections at P7. (C,D) Detection of lacZ expression by X-gal staining of transverse sections from the forelimb level of seven day old pups carrying the ECR9wt-lacZ (animal #1) (C) or the ECR9mt-lacZ (animal #2) (D) transgene. Only spinal cord and adjacent tissues are shown. Size bar, 200 µm. (E–J) Co-immunohistochemistry was performed on transverse sections of ECR9wt-lacZ transgenic animal #1 using antibodies directed against β-galactosidase (in red) in combination with antibodies directed against Sox10 (E), Olig2 (F), Myrf (G), Pdgfra (H), Gfap (I), and NeuN (J) (all in green). Pictures were taken from the dorsal funiculus for E–I and from the ventral grey matter for J. Size bars correspond to 10 µm.