Fig. 5. Consequences of forced expression of mouse Myf5 or MyoD in the neural tube for negative regulators of myogenesis. Adjacent transverse sections of embryos electroporated with mouse MyoD 1 day after electroporation were hybridised with the DIG-labelled antisense probes for mouse MyoD (A,E). The corresponding adjacent sections were hybridised with the ligands Delta1 (B), Serrate2 (C), the receptor Notch1 (D) and the HLH transcription factor Id2 (F). The framed regions in C,D show the right sides of the electroporated-neural tubes, where the expression of Serrate2 (C) and Notch1 (D) is upregulated compared with the control left sides of the neural tubes. The arrows in E,F show the areas where Id2 expression is upregulated (F) corresponding to the regions of the ectopic mouse MyoD (E).