EN
In this review, the molecular aspects of meiotic division and characteristics of proteins involved in mammalian oocytes maturation have been presented. Moreover, the role of competition has also been shown. The mammalian oocyte’s maturation is divided into: (i) nuclear maturation; (ii) cytoplasmic maturation; and (iii) genomic maturation. The maturation processes involves the stages associated with stored proteins and mRNA as well as the inherited changes in genomic DNA methylation. The proper procedure of all stages of maturation influences the achievement by oocytes of full developmental competence and fertilization ability. Both of these processes are associated with attaining by the embryos the ability of growth and development following embryonic genome activation (EGA). The stages of oocyte’s maturation are regulated by the expression of specific genes encoding proteins that are expressed during early folliculo-, and oogenesis, and is species dependent. The most important proteins regulating the process of oocytes maturation involves the following: transforming growth factor of the large super family group (TGF), connexins (Cx), mitogen activated protein kinase (MAPK), protein kinase A (PKA) and epidermal growth factor (EGF).