(F) Left panel: ZINB-WaVE (Risso et al, 2018, 2019) was used to statistically separate gene expression variability into parts linked to AP position and parts independent thereof. Scatter plot of ZINB-WaVE loadings separates known dorsal and ventral marker genes on ZINB-WaVE component 1. Right panel: Genes encoding homeodomain TFs and genes encoding Ig domain molecules (see color code) show high loadings on ZINB-WaVE component 1 and 3, demonstrating high variability independent of AP position. 