a, b, Large area survey images of RFP-labelled axons in composite mosaic scans of horizontal sections. Tracer-injection sites are denoted by RFP-PrSp. a, Multiple channel fluorescent images showing BDA-labelled axons and GFAP-labelled astrocytes that demarcate astrocyte scar proximal borders and distal borders around the non-neural lesion core after SCI. GFAP-staining shows that SCI lesions were anatomically complete across the entire width of the spinal cord, with large lesion cores in a control rat (left), and in a rat treated with stimulatory AAV plus growth factors (right). In the control rat, few axons reach the lesion centre or beyond. In the treated rat, many axons regrow through the lesion core and reach or pass 3 mm beyond the lesion centre, which is the equivalent length of a full thoracic spinal segment in rats47. b, Completeness of SCI lesions was confirmed in all rats used in qualitative and quantitative evaluations by confirming that no axons were present at 5 mm or more past lesion centres, as shown here for control rats (top) and treated rats (middle), whereas in uninjured rats, abundant labelled axons are present at an equivalent distance past the RFP-injection site.