Fig. 6. Msx3 induces neural progenitor cells to adopt a dorsal cell fate. (A-F) Immunofluorescence labeling of Cath1 in HH20-22 neural tubes. Electroporation of Msx3 in HH10-12 (A,B) or HH14-16 (D,E) embryos induces ventral ectopic expression of Cath1 at HH20-22. (B,E) Higher magnification images of the electroporated (right) side of the neural tubes in A and D showing Cath1 (red) and Msx (green) double positive cells (yellow, arrows) and Cath1⁺Msx^- cells (red, arrowheads). Overexpression of Msx3a does not induce ectopic Cath1 expression (C,F). (G) Bar graph indicating number of Cath1⁺ cells/section in Msx3-versus Msx3a-electroporated embryos (late indicates electroporation at HH14-16; early indicates electroporation at HH10-12) (mean±s.e.m., n=16 sections from at least four embryos; ^***P<0.001, ^**P<0.005). In all panels, left is the control side and right is the electroporated side. Scale bars: 150 µm in A,C,D,F; 75 µm in B,E.