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Updated: Sep 20, 2025
Author Spotlight: Elucidating the Dynamics of Mechano-Transduction and Nuclear Agitation in Mouse Oocytes
Published on: January 12, 2024
Cytoplasmic streaming induced by intracytoplasmic spindle translocation contributes to developmental competence
Shoko Ikeda1, Hiroko Fukasawa1, Tadashi Mabuchi1
1Department of Obstetrics and Gynecology, Faculty of Medicine, University of Yamanashi, Yamanashi, Japan.
Objective:
To evaluate the developmental competency of mouse metaphase II oocytes and the pattern of mitochondrial positioning through cytoplasmic streaming in mouse metaphase II oocytes.
Design:
We observed cytoplasmic streaming as movement indicated by fluorescently stained mitochondria using a newly developed method in which the spindle is translocated to the opposite site of the oocyte. This method is termed as intracytoplasmic spindle translocation (ICST).
Setting:
University research laboratory.
Animals:
Female B6D2F1 mice.
Intervention(S):
None.
Main Outcome Measure(S):
Fresh oocytes, postovulatory-aged oocytes, and oocytes treated with cytochalasin B were classified based on the presence of cytoplasmic streaming induced by ICST. The pattern of redistributed mitochondria and developmental competence caused by parthenogenetic activation were evaluated in oocytes with or without cytoplasmic streaming.
Result(S):
Induced cytoplasmic streaming occurred in 84% of the fresh oocytes but not in the postovulatory-aged oocytes and the oocytes treated with cytochalasin B. Abnormal mitochondrial aggregation was observed in oocytes in which cytoplasmic streaming was not induced. Furthermore, the developmental competence was significantly lower in oocytes without cytoplasmic streaming.
Conclusion(S):
Cytoplasmic streaming induced by ICST contributes to developmental competence through the redistribution of mitochondria and may be a valuable criterion for predicting early developmental competence in mouse oocytes.
Insights
Cytoplasmic streaming in mouse oocytes is crucial for development. This process, induced by intracytoplasmic spindle translocation (ICST), ensures proper mitochondrial distribution, enhancing developmental competence.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cell Biology
Background:
- Mitochondrial distribution is critical for oocyte developmental competence.
- Cytoplasmic streaming plays a role in intracellular organization.
- Understanding these processes is key to improving assisted reproductive technologies.
Purpose of the Study:
- To evaluate the developmental competency of mouse metaphase II oocytes.
- To investigate the role of cytoplasmic streaming in mitochondrial positioning.
- To assess the impact of induced cytoplasmic streaming on oocyte development.
Main Methods:
- Developed and utilized intracytoplasmic spindle translocation (ICST) to induce cytoplasmic streaming.
- Observed mitochondrial movement using fluorescent staining.
- Assessed developmental competence following parthenogenetic activation in oocytes with and without induced streaming.
Main Results:
- Induced cytoplasmic streaming occurred in 84% of fresh oocytes.
- Postovulatory-aged oocytes and cytochalasin B-treated oocytes failed to exhibit streaming.
- Oocytes without streaming showed abnormal mitochondrial aggregation and significantly lower developmental competence.
Conclusions:
- Induced cytoplasmic streaming via ICST is vital for mitochondrial redistribution.
- This streaming process significantly contributes to the developmental competence of mouse oocytes.
- Cytoplasmic streaming may serve as a predictive marker for early oocyte developmental potential.
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