Oocyte maturation is the key period in female gamete formation. Two successive meiotic divisions ensure that mature oocytes will contain a haploid number of chromosomes, while highly asymmetric cleavages make sure that the majority of cytoplasmic resources necessary for embryo development will remain within the oocyte and will not be lost within the polar bodies. Therefore, the cell divisions during oocyte maturation differ fundamentally from all other cell divisions by the absence of S phase between the two M phases, and by an extreme polarization of the dividing cell. In addition, all this happens in a huge cell, making rigorous temporal and spatial coordination both necessary and extremely difficult. To this end, the sequence of events upon oocyte maturation must be carefully controlled and constantly corrected. A part of this control relies on protein phosphorylation, orchestrated by kinases and phosphatases, of which a major role is attributed to serine-threonine kinases.
展开▼
