Supplementary Figure 1: Isolation of human early embryos for single-cell DNA methylome analysis.

a, Morphologies of oocytes and human early embryos at different developmental stages. Scale bar, 100 μm. b–f, The polar body and nuclear region of MII oocytes were biopsied by laser-assisted micromanipulation. Scale bar, 100 μm. b, Bright-field image of an MII oocyte. c, Staining with Hoechst 33342 dye to confirm the absence of genomic contaminants and reveal the nuclear region (arrow) and the first polar body (triangle) of the MII oocyte. d, Bright-field image of the aspiration of a polar body of an MII oocyte (triangle). e, Bright-field image of aspiration of the nuclear region of an MII oocyte (arrow). f, Hoechst 33342 staining showing aspiration of the nuclear region of an MII oocyte (arrow). g, Heat map showing the pairwise correlations of euploid single cells from different developmental stages. Unsupervised hierarchical clustering indicated that there were at least three major clusters, representing the sperm and male pronuclei (cluster I), GV and MII oocytes and female pronuclei (cluster II), and the cells from cleavage-stage embryos (cluster III), corresponding to the hypermethylation, intermediate methylation, and hypomethylation features of the different cell types.