Fig. 7. Abnormal projection of proprioceptive afferents in Dcc^–/– mutants at E18.5. (A,B) Immunocytochemical staining of Lmx1b shows the distribution of Lmx1b⁺ neurons in the superficial dorsal horn of the wild-type mice (A), and the region lacking Lmx1b⁺ neurons (arrow in B) in the dorsal horn of Dcc^–/– mutants at E18.5. (C,D) 2H3 staining shows the absence of 2H3⁺ primary afferents to the ventral horn (double arrowhead in D) and its abnormal location in the superficial dorsal horn (arrow in D) in Dcc^–/– mutants (D), compared with wild-type mice (C). (E,F) TrkA immunostaining shows the absence of TrkA⁺ primary afferent in the medial superficial dorsal horn in Dcc^–/– mutants (arrow in F). In wild-type mice, TrkA⁺ fibers are evenly distributed in the superficial dorsal horn (E). (G,H) DiI labeling shows a dramatic reduction of proprioceptive projection to the ventral horn (large arrow in H) and abnormal projection to the midline region (small arrow in H) of Dcc^–/– mutant, compared with wild-type mice (G). Broken white lines outline the ventral horn of the spinal cord. Scale bars: 100 µm.