Fig. 2: Classification of micronuclei and the developmental potential of those embryos at the two-cell stage.

a Histones in two-cell stage embryos were observed by fluorescent microscopy, and micronuclei were classified into three categories based on their positional relationship to the nucleus. ACS Abnormal chromosome segregation, IFM Independent floating micronucleus, EPM Equal positioned micronuclei, NBM Nuclear binding micronuclei, NCS Normal chromosome segregation. Scale bar: 10 µm. b Rate of ACS embryos in each type of classification. c Blastocysts developed from each type of ACS or NCS embryo after 3 days of culture. Bar, 50 µm. d Developmental potential of each type of ACS or NCS embryos to the blastocyst. The error bar indicates standard error. e Fluorescence observation was performed at the two-cell stage to detect micronuclei (e-1 and e-2). Two-cell stage embryos were cultured individually to the blastocyst stage. Embryos that developed into blastocysts (e-3) were transferred to an ES cell establishment medium to observe outgrowth (e-4) and establishment of ES cells. Established ES cells were examined for their chromosome number (e-5) and the normality of the cell lines. Bar, 10 µm (e-1–e-3) and 100 µm (e-4).