Desai N, et al. - Researchers examined if embryonic potential could be assessed with blastomere spatial arrangement in early human embryos. They retrospectively analyzed the prospectively collected data of patients undergoing a single blastocyst transfer. They determined cleavage plane orientation, blastomere arrangement, and morphokinetic behavior in detail in a total of 716 embryos. Observation revealed significant differences regarding developmental kinetics between tetrahedral (TET) and nontetrahedral embryos (nTET). Final blastomere spatial arrangement was identified to be directed by cleavage plane orientation during the first three divisions. Embryos, most likely to develop into good-quality blastocysts for cryopreservation/transfer, were frequently noted in correlation with TET formation at the four-cell stage.