Fig. 7. ARTN promotes neurite outgrowth and attracts growing axons. (A-F) Representative pictures of STG explants stained with anti-ß tubulin antibodies. Explants were dissected out from E13.5 mouse embryos and cultured in the presence of NT3 (100 ng/ml (B)), NRTN (20 ng/ml (C), 100 ng/ml (D)) and ARTN (20 ng/ml (E), 100 ng/ml (F)). (A) No factor. (E,F) Moderate and robust neurite outgrowth is induced by lower and higher concentrations of ARTN, respectively. (G) Axon-covering area was measured by use of NIH Image software (three explants for each condition; bars indicate mean standard errors). (H,I) ARTN-impregnated bead (dotted circle) induces robust neurite outgrowth of the sympathetic ganglion explant and directs growing axons toward the bead. Note that axons emanating from the distal side of the explant steer towards the source of ARTN (arrows in I). Scale bar: 350 µm for A-F; 250 µm for H,I.