[Maternal factors affecting development of early mouse embryos].

In vertebrates, oocytes undergo a series of maturation steps, arresting at metaphase II, and can then be fertilized by a sperm. Fertilization initiates molecular events that lead to the activation of early embryonic development. Fertilized oocytes or activated reconstituted embryos then activate the zygotic genome, a crucial event that initiates early embryonic development. The functions of the maternal factors derived from oocytes are different at various mouse embryonic developmental stages. Mouse zygotic genome is activated at the two-cell stage which implies that embryonic development is transferred from the oocyte itself to the embryo. Sometimes mouse embryos are blocked at the two-cell stage, for which the mechanism is not clear. So exploring the functions of some maternal factors in the two-cell stage embryos may help us to understand the potential reasons for early embryonic development failure. Reprogramming a foreign and terminally differentiated somatic nucleus by transferring it to the enucleated oocyte cytoplasm triggers epigenetic changes that eventually lead to the birth of a viable animal. This indicates the oocyte cytoplasm plays a critical role in the development of reconstructed embryos.