Movie S1

Time-lapse imaging of preimplantation Hprt^RED/Hprt^GFP embryos. Morula stage embryos (E2.5) from oviducts were cultured in potassium simplex optimized medium. Using confocal microscopy, images were taken at 15-min intervals with three channels (bright field, 488 and 561 nm) for up to 5 days. For each embryo, 66 images were taken in the Z-axis at 2-μm intervals for a total depth of ~140 μm.