Wnt7a and Fzd7 facilitate directed cell migration. (A) Scratch migration assay with mouse primary myoblasts that were stimulated with Wnt7a or vehicle. Error bars represent means ± SEM; n = 3. *, P < 0.05. (B) Quantification of scratch assays using primary myoblasts overexpressing EV or Fzd7-Flag. Error bars represent means ± SEM; n = 3. ***, P < 0.001. (C) Primary myoblasts derived from Fzd7 knockout mice (Fzd7^−/−) do not respond to Wnt7a stimulation. Error bars represent means ± SEM; n ≥ 3. n.s., no significant difference. (D) Scratch migration assay showing that Fzd^−/− primary myoblasts migrate significantly less than heterozygous cells (Fzd7^+/−). Genetic Fzd7 knockout can be rescued by expression of Fzd7-Flag. Error bars represent means ± SEM; n = 3. ***, P < 0.001. (E) Quantification showing that canonical Wnt3a does not affect cell migration in scratch wound assays. Error bars represent means ± SEM; n = 3. (F) Mean velocity of satellite cells on single cultured myofibers as determined by live imaging. Error bars represent means ± SEM; n ≥ 27. *, P < 0.05. (G) The mean maximal speed of Wnt7a-stimulated satellite cells is not significantly different from the vehicle control. Error bars represent means ± SEM; n ≥ 27. (H) Quantification of the mean change in direction of Wnt7a-treated satellite cells. In the presence of Wnt7a the cells migrate with increased directional persistence when compared to vehicle. Error bars represent means ± SEM; n ≥ 27. ***, P < 0.001. (I) Representative tracks of satellite cells on single cultured myofibers. The green “x” represents the start of imaging, and the blue “x” is the stop. Fewer changes in directional motility can be observed for the Wnt7a-treated satellite cell.