a, Immunostaining of H3K36me3 in oocytes and early embryos. Scale bars: 20 μm. One representative result out of three independent experiments is shown. PB, polar body. b, A snapshot of UCSC browser showing H3K36me3 enrichment in two replicates of sperm, 1C, late 2C, 8C and ICM from blastocyst. c, Hierarchical clustering analysis of H3K36me3 in individual replicates of mouse early embryos at various stages. d, Pearson correlations for pairwise comparisons of H3K36me3 enrichment at individual stages (n = 2). Two replicates were done for each sample. e, A bar chart showing the percentages of reads assigned to the maternal or paternal allele in mouse embryos at individual stage.