Molecular Mechanisms of Prophase I Meiotic Arrest Maintenance and Meiotic Resumption in Mammalian Oocytes: Current State of the Art

Introduction: The key molecules which plays an important role in meiotic resumption are the proteins involved in the MPF-complex regulatory pathway and Mos-MAPK molecular cascade.

Aim: To evaluate the expression levels of the key genes involved in meiotic resumption in murine oocytes.

M&M: Two groups of oocytes were used for the analysis: immature oocytes (with an average diameter about 70 µm) and the fully-grown ones (with an average diameter about 80 µm). Oocytes were extracted from ovarian follicles mechanically at the GV (germinal vesicle) stage. Then, cumulus cells also were removed mechanically by gentle pipetting. The samples for molecular genetic analysis were compound of 10 oocytes in each sample. After that oocytes were subjected for quantitative real-time PCR analysis using the SuperScript® III CellDirect cDNA Synthesis (Invitrogen) kit according to the manufacturer recommendations.

Results: It has been shown that the expression levels of important for meiotic resumption genes such as Mos, Cyclin B, CDK1 in fully-grown oocytes is statistically (p<0,05), higher in comparison to non-fully-grown oocytes.

Conclusion: Elucidation of key mechanisms which affect acquisition of meiotic competence by oocyte plays a pivotal role for the ART and further experiments dedicated for the detection of expression levels of other genes in oocytes are required.