Fig. 2. Morphology, distribution and migration of wild-type and Lmx1b mutant dorsal horn neurons. (A,C,E) Nissl staining of wild-type embryos. (B,D,F) Nissl staining of Lmx1b^-/- embryos. (A,B) At E12.5, no major difference was found between wild-type (A) and mutant embryos (B). (C,D) At E15.5, in wild-type, laminae I-II and laminae III-V are distinguishable, brackets outline the domain of laminae I-II and III-V, respectively. In Lmx1b^-/- embryo, no clear boundary between laminae I-II and III-V exists (bracket outlines the whole domain). (E,F) Lower magnification of C,D. In wild-type embryo, the dorsal funiculus is enlarged (E, arrow), whereas in Lmx1b mutant it is smaller (F, arrow). (G) Wild-type embryo at E14.5: neurons labeled with BrdU at E11.5 are not detected in the outer aspect of laminae I-II (inset indicating a high magnification). Bracket outlines the most superficial layer. (H) Lmx1b mutant embryo at E14.5: neurons labeled with BrdU at E11.5 are detected in the most superficial layer (bracket in the insert). (I,J) Higher magnification view of G,H showing the dorsal horn that is divided into the medial one-third (Med 1/3) and lateral two-thirds (Lat 2/3) region by lines for quantitative analysis. (K) Quantitative comparison of BrdU-labeled neurons in the medial one-third region and lateral two-thirds region between wild-type (white bar) and Lmx1b^-/- embryos (black bar). Asterisks indicate significant difference using Student's t-test P<0.0001. Scale bars: 100 µm in A-D,H; 200 µm in E,F; 60 µm in inset in H.