(a) Schematic of extracting kymograph information from tissue data by averaging Venus::HES5 intensities observed in E10.5 heterozygous spinal cord slices to generate one intensity profile in the dorsal-ventral axis per timepoint (see Materials and Methods). (b) Representative kymograph data showing spatiotemporal Venus::HES5 expression profile along ventral-dorsal direction in a 15μm wide apical region and observed over 14h; local bands of 20μm width in D-V; region of interest markers indicate: *low to high, **high to low and ***re-occurring high/low activity in the same area. 