Fig. 1

Summary of the experimental procedures and gene expression pattern. a Chicken embryo at stage 24, which was used for the surgery in the present study. b–e Summary of surgical procedures. b The schematic diagram of the surgical procedure. The distal one-quarter was isolated and stabbed with a gelatin bead. c The distal one-quarter of the limb bud was dissected out and the isolated part was used for the graft. d The next two quarters, the intermediate part, was removed. e The remaining one-quarter of the stump was stuck with the distal graft and the bead. f–m Gene expression pattern in non-amputated limb buds (f–i) and operated limb buds (j–m). Pg-h (Aggrecan) expression (f, j), Meis2 expression (g, k), Shox2 expression (h, l), and HoxA13 expression (i, m). The circles indicate the position of the grafted bead (J–M). The scale bars in a, b, c, and F are 2, 1, 1, and 0.5 mm, respectively