Figure 4. Netrin1 repels Unc5C-positive neocortical axons.

Images showing the axonal trajectory of neurons electroporated with Unc5C (a) or EGFP (b) on encountering neutral BSA-coated beads (arrows) or Netrin1-coated beads (arrows). Unc5C-positive fibres are unaffected by BSA-coated beads, placed along the midline, and continue along their initial trajectory to project into the contralateral hemisphere. Unc5C-positive fibres, upon encountering a Netrin1 source in the midline show clear repulsive behaviour with fibres projecting either dorsal or ventral to their initial path, but none continuing into the contralateral hemisphere. Wild-type axons electroporated with only EGFP (with endogenous Unc5C) are unaffected by the BSA beads and are repelled by the Netrin1 beads similar to the Unc5C overexpressing axons. Scale bar specified in the figure.