(a) Immunohistological analysis of Pax7 (red) and laminin (green) in muscle of control and coPtpn11 mutant mice; DAPI (blue) was used as a counterstain. Arrowheads point to Pax7+ cells. (b) Quantification of Pax7+ cells per 100 fibers. (c) Immunohistological analysis of Pax7 (red), laminin (blue) and BrdU (green) in forelimb muscles of control and coPtpn11 mutants at P7. Arrowheads point to Pax7+BrdU+ cells. (d,e) Quantification of Pax7+ cells that incorporated BrdU (d) or co-expressed Ki67 (e) at E16, E18, P0 and P7 in control and coPtpn11 mutants; the BrdU pulse was given for 2 hr. (f) Pax7 (red) and Ki67 (green) immunostaining of cultured myogenic progenitor cells isolated from control and coPtpn11 mutant mice that carry the RosaeYFP allele; YFP-positive cells were isolated by FACS and cultured for 18–20 hr. Arrowheads show Pax7+Ki67+ cells. (g,h) Quantification of cultured Pax7+ cells that incorporate BrdU (g) or co-express Ki67 (h) at E14.5, E15.5 and P0; the BrdU pulse was given for 1 hr. (i) Scheme for GS493 injections during postnatal growth. (j) Immunohistological analysis of Pax7 (red), Ki67 (green) and collagen IV (ColIV, blue) in forelimb muscles (P8) of animals treated with GS493 or vehicle from P6 to P8. Arrowheads point to Pax7+Ki67+ cells. (k,l) Quantification of Pax7+ cells that co-express Ki67 (k) or incorporated BrdU (l) in muscle of GS493- or vehicle-treated animals. n.s. = not significant, *p<0.05, **p<0.01, ***p<0.001. Error bars show S.E.M. Scale bars 25 µm in a, c, j, 15 µm in f.