Fig. 9. Ephrin-A2 inhibits outgrowth of IO axons in vitro in a region-specific manner. Explants of the medial (A,C) and lateral (B,D) IO prepared from E8 embryos were grown on homogeneous carpets of 293T cell membrane, either mock-transfected (A,B), or transfected with pcDNA1-ephrin-A2 (C,D). Whereas axons from the lateral IO grow equally well on both membranes, axon outgrowth from the medial IO was significantly inhibited on the ephrin-A2 membrane. Scale bar, 500 µm.