Fig. 4. Netrin 1 suppresses axon outgrowth from DRG explants in vitro. E13.5 mouse DRG explants were co-cultured for 24-48 hours with aggregates of BHK cells expressing EGFP (A) or netrin 1 (B,C) in collagen gel. Explants were stained with anti-neurofilament antibody. Axon outgrowth from DRG explants co-cultured with netrin 1-expressing cells is inhibited (B) compared with that of control DRG explants cultured with EGFP-expressing cells (A). (C) The inhibitory effects are neutralized by the application of 2 µg/ml anti-netrin 1 rabbit antibodies. Scale bar: 250 µm. (D) Quantification of axon growth from DRG. The areas covered by neurofilament-positive axons were measured. ^*P<0.05.