gad and pkd2l1 expression in double mutant embryos. Lateral views of gad (A–C) or pkd2l1 (F,G) expression in 24 h WT sibling and double mutant embryos as indicated. Dorsal, top; anterior, left. Scale bar = 50 microns. Dashed lines indicate ventral limit of spinal cord. The approximate proportions of medial and lateral row 3 cells are indicated by horizontal lines separating the number of medially-located cells (bottom and indicated where there is space with an “M”) from the number of laterally-located cells (top and indicated where there is space with a “L”). Mean number of cells expressing gad or pkd2l1 in each D/V row of precisely-defined spinal cord region adjacent to somites 6–10 in WT and single and double mutant embryos (D,E,H). All counts are an average of at least 4 embryos. Error bars indicate SEM. Statistically significant comparisons are indicated with brackets and stars. ***P < 0.001, **P < 0.01, *P < 0.05. In (E), there is no statistically significant difference between any row 1 values or between tal1 single mutants and tal1;gata3 double mutants in row 4+. In (H), there is no statistically significant difference between any row 1 values. For P-values see Supplementary Table 3. Cross-sectional schematic indicating positions of KA″, KA′, and V2b neurons (I).
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