Theoretical and applied aspects of epigenetic reprogramming in mammalian development

Epigenetic reprogramming implies changes in germ and somatic cells of an embryo, which are the consequences of gene activity regulation by means of DNA methylation, histone modification, and altered chromatin compaction. This suggests that epigenetic changes in mammalian cell nucleus occur during gametogenesis and totipotent zygote formation. Epigenetic changes proceed during morphological and inductive interactions between cleaving blastomeres and subsequent interactions between the inner cell contents and trophoectoderm, as well as when the germinal layers (blastophyllums) and their derivatives appear, i.e., during the embryonic histogenesis [1]. Some authors [2-4] assume that in vitro fertilization and consequent human zygote cultivation lead to defects of genomic imprinting [2-4]. This leads to abnormal embryonic and fetal development and increased incidence of hereditary diseases-Beckwith-Wiederman or Angelman syndromes. The present review, critically considers the facts on which the above hypothesis is based.