Somite boundary formation in relation to the first LuVeLu waves. Related to Fig. 4A-D. An embryo expressing the dynamic Notch signaling reporter LuVeLu (cyan) and nucleus marker R26-H2BmCherry (red) was imaged from late allantois bud stage onwards. To monitor the formation of somite boundaries, visible as clefts between nuclei, the embryo was mounted with the distal aspect toward the detection objective (posterior up). The same embryo with only the R26-H2BmCherry signal (red) is shown on the right, for better visualization of clefts. Time is indicated in hr:min.