Chicken embryos were windowed at E3; then, 50 μg per day of αbtx dissolved in sterile saline or saline alone was applied in 50 μl aliquots daily from E7 to E10. Ganglia were harvested at E11 and total RNA was extracted and reverse transcribed. Target gene expression was quantified in triplicate with quantitative real-time PCR using TaqMan probes. Values given are the mean ± SE of RNA isolated from three independent groups of experiments, pooling 14–16 ganglia from each treatment. *p < 0.01, one-way ANOVA with Tukey's post hoc test.