Fig. 5.

CD2019 promotes growth of CST axons following lesion. Rats were treated at the time of lesion by i.c.v. with 180 ng/kg CD2019/day for 14 days and then analysed 28 days later. Axonal outgrowth was determined with BDA tracing in longitudinal sections of spinal cord rostral (left) and caudal (right) to the lesion site. In vehicle-treated rats BDA-labelled axons were apparent along the CST, rostral to the injury (A–C), but absent caudal to it (D–G). BDA-labelled fibres can be seen in adjacent grey matter, running parallel (D, E, arrows) or diverting away (F–G, arrowheads) from the white matter region of the injured CST. In contrast, CD2019-treated rats exhibited BDA-labelled fibres in the CST caudal to the lesion site (H). Proximal to the lesion, BDA fibres (arrows) can be seen growing around the lesion site through the grey matter (I-J) and within the white matter region of the injured CST (K). Caudally to the injured CST, BDA-labelled fibres can be seen growing longitudinally within (arrows) or tangentially (arrowheads) to the white matter tract (L–N). In the grey matter of the forelimb innervation field many axons can be seen (N). Saggital sections of the lesion site (O–Q), in vehicle-treated animals axons cannot be detected in the lesion site (O), in contrast in CD2019-treated animals axonal outgrowth (arrows) is observed in the lesion site (P,Q). Black lines indicate the rostral part of the lesion for O–Q. Scale bars = 500 μm (A–N), 100 μm (O–Q).