A, the methylation statuses of Oct4 and Thy1 at the 4-cell and blastocyst stages of NT-CON, NT-negative and NT-siRNA embryos, B and B', the methylation levels of Oct4 at the 4-cell and blastocyst stages of NT-CON, NT-negative and NT-siRNA embryos, C and C', the methylation levels of Thy1 at the 4-cell and blastocyst stages of NT-CON, NT-negative and NT-siRNA embryos, D and E, relative transcripts of Oct4 and Thy1 at the 4-cell and blastocyst stages of NT-CON, NT-negative and NT-siRNA embryos, respectively. Dnmt1 knockdown improved the methylation reprogramming of Oct4 and Thy1 and promoted the activation of Oct4 and the silence of Thy1 in cloned embryos. The transcript abundance of Oct4 or Thy1 in 4-cell cloned embryos was considered to be the control. The data were expressed as mean ± SEM. a-bValues at a given stage or group in the same column chart with different superscripts differ significantly (P<0.05).