Fig. 7. Expression of Pdgfra, Olig2 and Nkx2.2 in the Pdgfa mutants at E13.5 (A-F) and E16.5 (G-N). (A-F) Immediately adjacent sections from E13.5 wild-type (A-C) and mutant (D-F) spinal cords were probed for Pdgfra (A,D), Olig2 (B,E) and Nkx2.2 (C,F) by in situ hybridization. (G-N) Adjacent sections from E16.5 wild-type (G-J) and mutant (K-N) spinal cords were stained with Pdgfra (G,K), Olig2 (H,L), Nkx2.2 (I,M) and MBP (J,N). At these two stages, expression of Pdgfra and Olig2 is delayed and reduced in the mutants, whereas expression of Nkx2.2 and MBP is not affected. Note the similar patterns of expression of Nkx2.2 and MBP (I-J,M-N).