Fig. 3. Impaired ventral migration of early-born neurons in Dcc^–/– mutants. (A,B) Nissl staining of the dorsal horn of wild-type embryo (A) and DCC^–/– mutant (B) embryos. Arrow in (B) indicates an area that is lightly stained with Nissl in the medial part of laminae I-II. (C,D) Immunocytochemical staining of Lmx1b in the dorsal horn of wild-type (C) and Dcc^–/– mutant (D) embryos shows Lmx1b⁺ neurons in laminae I-II (arrow and arrowhead in C) and the region lacking Lmx1b staining (arrow in D). (E,F) X-gal staining of E14.5 Math1^+/– (E) and Math1^+/–/Dcc^–/– embryos (F) shows an absence of Math1⁺ cells in the dorsal horn (arrow) of Math1^+/– embryos in contrast to the ectopic Math1⁺ cells in the medial superficial dorsal horn in Dcc^–/– mutants (arrow in F). Arrowheads indicate Math1⁺ cells in the intermediate region of the spinal cord. (G,H) Isl1 staining of wild-type (G) and Dcc^–/– mutant (H) embryos shows the ectopic Isl1⁺ cells in the dorsal horn of Dcc^–/– mutants (arrow in H) when compared with wild-type control. Arrowheads indicate Isl1⁺ cells in the intermediate region of the spinal cord. (I,J) E10.5 BrdU-labeled neurons are detected in the dorsal half of the spinal cord of wild-type (I) and Dcc^–/– mutant (J) embryos at E14.5. Arrows indicate a cluster of BrdU-labeled neurons in the medial superficial dorsal horn of the mutant (J), but not in wild-type (I). Arrowheads indicate BrdU-labeled neurons at the intermediate region of wild-type and Dcc^–/– mutant embryos. (K,L). E11.5 BrdU-labeled neurons are seen in the dorsal horn of wild-type (K) and Dcc^–/– mutant (L) embryos. Arrows indicate an absence of BrdU-labeled neurons in the medial superficial dorsal horn of the mutants. Scale bars: 100 µm.