Movie 5

Live imaging of E12.5+12h Fucci reporter shows that IK G₁ cells do not contribute clonally to the primary EK in the molar
Fluorescence confocal microscopy time-lapse of E12.5+12h Fucci explant, showing the contribution of cell cycle stages at bud stage and initiation of the pEK. Image stacks were taken at 20min intervals, and the playback speed here is five frames per second. The movie shows volume rendering of Fucci G₁/G₀ nuclei (red) and S/G₂/M (green) overview of the mandible at the start of imaging (initial molar bud outlined white). In the close up of the molar IK is marked with an open circle and the location where the pEK will be initiated (marked with a closed circle). Time lapse shows volume rendering of both channels merged and separately. In track view the perimeter of the mature bud is outlined in white. Individual cell tracks are shown as a dragon tail rendering showing a subset of ten subsequent points in each track, IK G₁/G₀ (red), pEK G₁/G₀ (magenta), S/G₂/M (green). A wave of cell proliferation contributed to rapid bud growth while the IK cells stayed in G₁/G₀ in the mesial part of the bud. The pEK G₁/G₀ cells were initiated de novo deep in the tip of the invaginating bud with no clonal contribution from the IK.