Abstract
Vol.39 No.2
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Original
Improvement of the early developmental ability of in vitro matured MII oocytes using a spindle transfer technique
JMOR, 39(2) 111-115, 2022
[Purpose] The early developmental ability of MII oocytes matured in vitro (IVM-MII oocyte) after in vitro fertilization (IVF) is lower than that of fresh MII oocytes matured in vivo. The low early developmental ability of IVM-MII oocytes is thought to be due to delayed cytoplasmic maturation rather than nuclear maturation. We compared the early developmental ability of IVM-MII oocytes with that of reconstructed MII oocytes generated by microinjecting the spindles of IVM-MII oocytes into the enucleated cytoplasts of fresh MII oocytes. [Methods] First, fresh MII oocytes and immature oocytes at the GV stage were collected from B6D2F1 female mice. The GV stage oocytes were maturated in vitro. Using the metaphase II spindle injection (MESI) technique, we generated reconstructed MII oocytes by injecting the spindles from IVM-MII oocytes into the cytoplasts of fresh MII oocytes. [Result] The percentage of oocytes reaching the expanded blastocyst and hatched blastocyst stages was 47.5% (95/200) in the reconstructed MII oocytes, a significantly higher percentage than the 18.3% (42/229) obtained with IVM-MII oocytes (P < 0.001). [Conclusion] These results support previous reports that the low early developmental ability of IVM-MII oocytes is due to an immature cytoplast.
