Comparison of neurite outgrowth from ciliary, trigeminal, vestibular, and cochlear ganglion explants elicited by NRTN at different embryonic stages. A, B, E9 ciliary ganglion explant with (A) or without (B) NRTN at 50 ng/ml. C, E16 ciliary ganglion explant with NRTN at 100 ng/ml. D, E, E9 (D) and E12 (E) trigeminal ganglion explant cultured with NRTN at 100 ng/ml.F, E16 cochlear ganglion explant with NRTN at 100 ng/ml.G, E9 vestibular ganglion explant with NRTN at 100 ng/ml. H, I, E16 vestibular ganglion explant grown with NRTN at 100 ng/ml (H) or 10 ng/ml (I). Note that NRTN induces an extensive outgrowth from the E9, but not from E16, ciliary ganglia. In contrast, NRTN has positive effects on E16, but not E9, vestibular ganglia. NRTN has no effect on E16 cochlear ganglion explant outgrowth. The culture was immunostained with a neurofilament antibody (A, G, H) or unstained phase-contrast micrographs (B–F, I). Scale bar (shown in I):A–C, F–I, 500 μm; D, E, 260 μm.