REGULATION OF GENE-EXPRESSION IN THE PREIMPLANTATION MOUSE EMBRYO

The maternal to zygotic transition, which entails activation of the em bryonic genome, is arguably the first important event that must occur following fertilization for further successful development. In mammali an preimplantation embryos, zygotic gene activation occurs at differen t developmental stages. What regulates the timing of gene expression, however, is poorly understood and the spectrum of genes that are expre ssed is ill-defined. This review will concentrate on results of experi ments derived from studies using preimplantation mouse embryos and wil l focus on when zygotic gene activation occurs and what regulates its timing, as well as approaches to analyze genes whose expression is act ivated.