Fig. 7. Dorsoventral patterning of the spinal cord. (A-D) Lhx1 (red) immunostaining of interneurons in the ventral spinal cords of E10.5 control (A), Cux2^neo/neo mutants (B) and Nestin-enhancer-driven Cux2-ires-EGFP transgenic (C,D) embryos. (E-H) Isl1 (blue) and Olig2 (red) co-labeling of control (E), Cux2^neo/neo mutant (F) and Cux2 transgenic embryos (G,H). Olig2 labels ventral motoneuron progenitors and Isl1 identifies post-mitotic motoneurons and v3 interneurons. (I,J) Nkx2.2 labeling of the ventral most progenitor domain in spinal cords from E10.5 control (I), Cux2^neo/neo mutant (J) and Cux2 transgenic (K,L) embryos. (M) Quantification of Cux2 gain- and loss-of-function on Isl1-positive motoneuron formation at E10.5. Cux2^neo/neo mutants (n=11) displayed a 32% increase (P=0.000003) in Isl1-positive motoneurons relative to controls (n=8), whereas Cux2 transgenic neural tubes showed a 20% decrease (n=4, P=0.053). A 61% increase in Isl1 numbers are observed when Cux2^neo/neo mutants are compared with transgenic embryos (P=0.001). (N) Quantification of Cux2 gain- and loss-of-function on the formation of Lhx1-positve ventral interneurons at E10.5. Cux2^neo/neo mutants displayed a 16% decrease (n=8, P=0.08) in Lhx1-positive cells relative to controls (n=4), while Cux2 transgenic neural tubes showed a 43% increase (n=4, P=0.006). A 70% decrease in Lhx1 numbers are observed when Cux2^neo/neo mutants are compared with transgenic embryos (P=0.0007). Data are summarized in Table S2 in the supplementary material.