Spinal cord transection and regeneration in Xenopus laevis regenerative and non-regenerative stages. (a,b) Xenopus laevis R-stage (a) and NR-stage (b), indicating the transection site at the mid-thoracic point (green and red arrows). (c-j) Immunofluorescence in longitudinal spinal cord sections using an anti-acetylated tubulin antibody to stain for axon growth after the injury. Insets show magnifications of boxed areas. While axon growth occurs across the lesion site in the R-stage, this is not the case for the NR-stage. Brackets, ablation gap. Arrowheads, wrapping of axons around the stump. Arrow, wisping or axonal growth tips into the ablation gap. Scale bars: (a, b) 1 cm, (c-j) 100 μm. dpt, days post transection; NR, non-regenerative; R, regenerative.