Fig. 5. Ectopic expression of ephrin-A5 results in a reduction of muscle precursor cells in the proximal forelimb. All images are confocal z-series (21 µm) from vibratome sections at forelimb levels. (A-D,E-H,I-L) Forelimbs from three different stage 17 embryos in which ephrin-A5/EGFP was targeted to the lateral plate mesoderm via in ovo electroporation at stage 13. For the top three rows, the contralateral, unelectroporated (control) limb is on the left (A,E,I). (B,F,J) Distribution of Pax7 muscle precursor cells in limbs ectopically expressing ephrin-A5. (C,G,K) Same field, EGFP images. (D,H,L) Merged Pax7 and EGFP images. Note that Pax7-positive cells cluster near the lateral dermomyotome in B,F, compared with controls (A,E). (M-P) Forelimbs from control embryos electroporated with pMES-EGFP. (M) Distribution of Pax7 cells in the contralateral, unelectroporated limb. (N-P) The distribution of Pax7 cells in the presence of EGFP alone is similar to the contralateral limb (M).