Methylation plays an important regulatory role in embryo development and organization.Somatic nuclear transfer embryos often show the abnormal mode of DNA methylation,DNA methyltransferase inhibitors can inhibit the levels of DNA methylation,so as to improve the efficiency of SCNT.The application of DNA methyltransferase inhibitors in animal somatic cell nuclear transfer was taken an overview in this paper.

Apoptosis is a process that cells autonomicly go to death,so that to maintain homeostasis and adapt to living environment.Apoptosis involves a series of gene activation,expression and regulation.It has been observed that there are the occurrence of apoptosis during preimplantation embryos development,but if the degree of apoptosis is beyond the normal range,and it is not conducive to the development of embryos.This paper provides a review of the current state of knowledge on apoptosis during preimplantation embryo development,in order to provide a theoretical basis for improving the quality of embryo in vitro culture.