Fig. 2. Retinal axon responses to EphB•ECD-Fc proteins in substratum choice assays. (A,C) Retinal axons, visualized with TR-phalloidin, grow freely into regions containing Fc control protein. (B,D) Reduced retinal axon growth on EphB2-ECD substratum region. Note tendency of individual axons to stop or turn at the border. C,D are higher magnification views of A,B at substratum border. Asterisks in A,B indicate test substratum region. Scale bars, 200 µm (A and B are same magnification, as are C and D).