Fig. 1. Expression of netrin 1 and its receptors in the developing spinal cord and DRG. (A-E) Expression of netrin 1 mRNA visualized by in situ hybridization on transverse sections of the mouse spinal cord. At E11.5 (A), netrin 1 is expressed in the floor plate and the ventral-most part of the ventricular zone of the neural tube. At E12.5 (B,D), netrin 1 mRNA is localized in the dorsolateral region of the cord (arrowheads in B,D) as well as the floor plate and the ventral ventricular zone. The boxed area is magnified in D. At E13.5 (C,E), netrin 1 expression in the dorsal spinal cord is decreased (arrowheads in C,E). The boxed area is magnified in E. (D) Netrin 1-expressing cells are localized near the DREZ (arrow). fp, floor plate. (F-I) In situ hybridization for Dcc (F), Unc5a (G), Unc5b (H) and Unc5c (I) in the E12.5 mouse DRG. Unc5a and Unc5c are expressed in the DRG, whereas Dcc and Unc5b cannot be detected. Sections were counterstained with Nuclear Fast Red. Scale bar: 200 µm in A-C; 100 µm in D-I.