Fig. 5. Effects of overexpression of Wnt5a and Wnt11 on fibre-type differentiation in vivo. Fluorescent images of transverse cryosections of day 8 (A-F) and stage 29 (G-J) chick wings that were infected with retroviruses expressing GFP (B), Wnt5a (D,F) or Wnt11 (H,J) at stage 18-20, and of the contralateral control wings (A,C,E,G,I). Wings have been visualized with antibody A4.1025, which recognizes slow and fast MyHCs (C,D,G,H, green), and antibody A4.840, which recognizes slow MyHC (E,F,I,J, red). (B) The embryo was pathogen free and viral spread has been visualized with an anti-GAG antibody. The arrows in (B) indicate viral spread throughout the limb bud and muscles (compare with A). The arrows in (E) and (F) compare equivalent muscles, showing an increase in slow MyHC expression in the manipulated limb (F). In the Wnt11-transfected limb, there are fewer slow fibres in the dorsal and ventral muscle masses (J) than in the contralateral limb (I). d, dorsal muscle mass; EDC, extensor digitorum communis; EIL, extensor indicis longus; EMR, extensor metacarpi radialis; EMU, extensor metacarpi ulnaris; FCU, flexor carpi ulnaris; FDP, flexor digitorum profundus; R, radius; u, ulna; v, ventral muscle mass. Scale bars: 200 µm in A-D; 100 µm in E-H.

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