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Development of mouse embryos derived from oocytes reconstructed by metaphase I spindle transfer
Yong Cheng1, Lei Lei, Duan-Cheng Wen
1State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, China.
Abstract:
Abnormal oocyte spindle is frequently associated with the infertility of aged women. Directly manipulating the metaphase I (MI) spindle may be a feasible method to overcome this kind of problem. Here, we report that the MI meiotic spindle can be removed from MI mouse oocytes and will autonomously divide into two daughter cells with the same size, morphology and an equal number of chromosomes after culture for 5 h in maturation medium. The division rate of the MI spindle reached 56% after 10-15 h of culture. After transferring the MI meiotic spindle into synchronous ooplasm by electrofusion, about 61% of the reconstructed oocytes continued to complete the first meiosis and extruded a normal first polar body. The matured reconstructed oocytes can also be fertilised. Approximately 50% of the 2-cell embryos developed to the morula stage after in vitro culture.
Insights
Researchers successfully isolated and divided mouse metaphase I (MI) spindles, demonstrating their potential to restore fertility in aged women by correcting abnormal oocyte spindles.
Area of Science:
- Reproductive biology
- Cell biology
- Developmental biology
Background:
- Abnormal oocyte spindles are a significant cause of infertility in aged women.
- Current methods to address this issue are limited, necessitating novel approaches.
Purpose of the Study:
- To investigate the feasibility of manipulating metaphase I (MI) spindles to overcome infertility associated with aging.
- To assess the developmental potential of oocytes reconstructed with isolated MI spindles.
Main Methods:
- Isolation of MI meiotic spindles from mouse oocytes.
- In vitro culture of isolated MI spindles to observe autonomous division.
- Electrofusion of isolated MI spindles into enucleated oocytes.
- Assessment of meiotic progression, fertilization, and early embryonic development in reconstructed oocytes.
Main Results:
- Isolated MI spindles autonomously divided into two equal daughter cells with consistent chromosome numbers.
- A 56% division rate of MI spindles was achieved after 10-15 hours of culture.
- 61% of reconstructed oocytes successfully completed meiosis and extruded a normal first polar body.
- Approximately 50% of fertilized reconstructed oocytes developed to the morula stage in vitro.
Conclusions:
- The study demonstrates the successful isolation, division, and functional integration of MI meiotic spindles.
- This technique shows promise for correcting oocyte aging-related infertility by restoring spindle function.
- Further research may lead to new assisted reproductive technologies for infertility treatment.