2-cell stage cells from WT or Kdm4e KO mice were collected from the oviducts directly into the cell lysis buffer The single-cell samples were collected in tubes with lysis component and ribonuclease inhibitor. Then we carried out the amplification by the Smart-Seq2 method. An Oligo-dT primer was introduced to the reverse transcription reaction for first-strand cDNA synthesis, followed by PCR amplification to enrich the cDNA and magbeads purification step to clean up the production. Then the cDNA production was checked by Qubit® 3.0 Flurometer and Agilent 2100 Bioanalyzer to ensure the expected production with length around 1~2kbp. Then the cDNA was sheared randomly by ultrasonic waves for Illumina library preparation protocol including DNA fragmentation, end repair, 3' ends A-tailing, adapter ligation, PCR amplification and library validation.