This movie illustrates the early division up to the four-cell stage of a C. elegans embryo expressing H2B::GFP by DIC and fluorescence microscopy. GFP-tagged histone H2B allows chromosome segregation to be followed. In wild-type, DNA replication generates two sets of sister chromatids that segregate toward opposite spindle poles during mitosis. The first C. elegans embryonic division of the P0 zygote is asymmetric and generates an anterior AB cell, and a smaller posterior P1 cell. These cells have different developmental fates and division timing, with AB dividing approximately 2 min before P1. Additionally, in early C. elegans embryonic cell cycles, S and M phases rapidly alternate without apparent gap phases. The movie corresponds to experiments shown in Fig. 3A and Fig S5 and Movie 7 of Mouysset et al. Movie is CIL 25634 and original data is CIL 35148.