Fig. 3

Newt limb muscle development and regeneration is independent of Pax7. a Pax7 ^−/− F₁ P. waltl have normal limb skeletal muscle. Note the similar myosin heavy chain (MHC) and laminin (Lam) staining in Pax7 ^−/− and WT animals. Scale bars = 200 µm in the overview and 20 µm in the insert. b Pax3-CRISPR mosaic animals have muscle-less limbs. Immunofluorescent staining for MHC in transverse sections of Pax3-CRISPR and control-CRISPR limbs. Scale bar = 100 µm. c Limb regeneration is not impaired in post-metamorphic Pax7 ^−/− F₁ animals. Scale bar = 1 mm. d Pax7 ^−/− F₁ animals regenerate normal skeletal muscle in the new limb. Note the indistinguishable myosin heavy chain (MHC) and laminin staining in Pax7 ^−/− and WT animals. Scale bar = 100 µm. e muscle-less limbs in Pax3-CRISPR mosaic animals (stage 45) regenerate muscle-less limbs. Immunofluorescent staining for MHC and the neuronal marker βIII-tubulin in transverse sections. Scale bar = 1 mm in the left panels showing animals and 100 µm in the right panels showing sections. Red dotted lines indicate amputation plane. White lines indicate section plane