A study on the correlation between maturation and quality of human oocytes

The success ratio of live birth after human in vitro fertilization and embryo transfer program is still around 12% Per oocyte retrieval cycle. A large number of mature oocytes became degenerate and unable to develop after insemination or implantation. In order to determine this discrepancy, assessment of maturation process as well as cytoplasmic maturity of the oocyte was performed. Initiation and completion of maturation were dependent on steroid metabolism and cyclic AMP in the oocyte cytoplasm. Extracellular calcium is another determinant factor of oocyte maturation. Phosphorylation of 23.5kD and 29.5kD protein was observed in the cytoplasm during maturation. In addition to cAMP, nuclear maturation is regulated by protein tyrosine phosphorylation in the cytoplasm. An inhibitor of Na+/H+ antiport appears to be effective in the procedure of cryopreservation but has no relationship with oocyte maturation. Quality of the oocyte consists of nuclear and cytoplasmic maturation.