Fig. 8. Hedgehog signaling is not sufficient for tail regeneration in the absence of the spinal cord. (A) Mock operated axolotl tail shows normal 7-day regenerate. (B) Control tail with spinal cord removed does not regenerate. (C) Agonist-treated tail without spinal cord also does not regenerate. Arrows point to the distal tip of the spinal cord in all panels. The dashed line marks the amputation plane. Scale bar: 0.5 mm.