(a) 20x snapshot of an ex-vivo slice culture of E10.5 spinal cord from Venus::HES5 heterozygous knock-in mouse, transverse section; delineated region (blue) correspond to data shown in (b-c). D- dorsal, V- ventral. (b) Spatial profile of Venus::HES5 intensity averaged over 2.5hrs with 0 distance representing the ventral end of kymograph; black line represents the trend in Venus::HES5 data across the domain produced using an polynomial order 6 (see Materials and Methods). (c) Detrended spatial profile of Venus::HES5 corresponding to data shown in (b). 