Fig. 6. Ectopically expressed ephrin A2 induces stalling and turning of cC-VC axons. EGFP alone or together with full-length chick ephrin A2 were electroporated in ovo at around stage 20. Electroporated hindbrains were taken for culture at stage 27-28, and cC-VC axons were anterogradely labelled with DiI. (A1) EGFP alone has no effect on cC-VC axons (n=15/16). (B1,C1) At the interface of an ectopic ephrin A2 domain, most cC-VC axons either stalled (B1,C1) or turned away to extend caudally (C1) (n=15/17). (A2-C2) Same images as the A1-C1, respectively, with EGFP signals removed. A small amount of axons grew into the ephrin A2 expression domain in both B2 and C2, suggesting the possibility that cC-VC axons might represent a heterogeneous population with respect to their responsiveness to ephrin A. Scale bar: 200 µm.