Fig. 1. GDNF and NRTN promote the neurite outgrowth and survival of ciliary ganglion neurons in vitro in a stage-specific manner. (A,B) E9 ciliary ganglion explant with (A) or without (B) NRTN at 50 ng/ml. (C,D) E16 ciliary ganglion explant with NRTN (C) or CNTF (D) at 50 ng/ml. Note that NRTN induces an extensive outgrowth from E9, but not from E16 ciliary ganglia. In contrast, CNTF has positive effects on E16 ciliary ganglion neurite outgrowth. A and D were immunostained with a TUJ1 antibody and B and C were unstained phase-contrast micrographs. Scar bar, 500 µm. (E,F) Quantitative analysis of neurite outgrowth from E9 (E) or E16 (F) ciliary ganglion explants in the presence of GDNF family ligands, CNTF or BDNF. Graphs show the average neurite length (± s.e.) for ciliary ganglion explants grown in medium alone or medium containing either GDNF, NRTN, ARTN, PSPN, CNTF or BDNF (50 ng/ml, for each factor) for 3 days. (G,H) Survival of E9 (G) or E16 (H) ciliary ganglion neurons in the presence of GDNF family ligands, CNTF or BDNF (50 ng/ml for each factor). Results are expressed as a percentage of the neurons that survived after 48 hours in culture (± s.e.). Note that the majority of E9 ciliary ganglion neurons are dependent on GDNF or NRTN (G), whereas only a sub-population of E16 ciliary ganglion neurons are supported by these factors (H). Each bar represents data from 7-14 explants. **, Significantly different from the control group (P<0.01).