3D movie of live-imaging analysis at 21 min after the disappearance of the pronuclear membrane of tripronuclear (3PN) zygotes derived from the conventional in vitro fertilization (c-IVF) and showing the positional relationship of the chromosomes and microtubules. This video is available from the online version of the article at https://doi.org/10.1530/REP-21-0061.