Surplus ventrolateral GABAergic neurons in fmr1 embryos are specified in the pMN progenitor domain. At 24 h post-fertilization, there are two populations of pMN-derived GABA+olig2+ cells in the ventral spinal cord, as shown through immunohistochemistry for gamma-aminobutyric acid (GABA) on transverse trunk spinal cord sections of Tg(olig2:EGFP) embryos: dorsal KA INs [yellow asterisks, (A’,A”,B’,B”)] and ventral lateral descending (VeLD) INs [cyan and magenta arrowheads, (A,A’,B,B’)]. Quantification of KA INs [(C); Mann–Whitney test] and VeLD INs [(D); two-tailed t-test] in wild-type and fmr1 embryos. Quantification reflects the average number of cells per section, averaged by embryo. Scale bar = 10 μm. P-values indicated in graphs, where p < 0.05 is considered significant.
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