EN
Near the end of the growth phase, mammalian oocyte achieves competence to undergo three aspects of maturation, i.e. nuclear, cytoplasmic and genomic. This review will consider some aspects of cytoplasmic and genomic maturation, as the nuclear maturation was already presented. The roles of the protein synthesis, bi-directional communication between oocyte and granulosa cells and calcium oscillations required for acquiring cytoplasmic maturation are discussed. The relevant information on genomic imprinting that causes functional differences between paternal and maternal genomes and plays an essential role in mammalian development is reviewed. Moreover, the present findings regarding oocyte-specific genes required for expression of cytoplasmic and genomic competencies are described.