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Localization of microfilaments during oocyte maturation of golden hamster
1Department of Obstetrics and Gynecology, Tohoku University School of Medicine, Sendai, Japan.
Abstract:
The localization and changes in microfilaments (MF) during golden hamster oocyte maturation were examined by an immunofluorescein method and confocal laser scanning microscopy (CLSM). We also studied the relationship between the changes in MF and oocyte nuclear and cytoplasmic maturation. During in vivo maturation, generalized submembranous MF were found initially which gradually became more prominent at the site of the first polar body extrusion. However, 43.7% of the in vitro matured metaphase 2 stage oocytes lacked the submembranous MF structure. This fact may partly account for the low fertilization rate of in vitro matured oocytes. MF were not found in the folicular oocytes cultured in cytochalasin D-containing medium, and metaphase-like chromosomes were located at the center of the oocyte and first polar body extrusion did not occur. Twenty-five percent of the oocytes, which were arrested at meiosis by hypoxanthine, synthesized submembranous MF structure although the nuclear stage of these oocytes was germinal vesicle. These facts suggest that MF plays a role in nuclear behavior but there are some differences in the changes taking place within the nucleus and MF. MF may play a role in oocyte cytoplasmic maturation although the details of this have yet to be established.
Insights
Microfilaments (MF) are crucial for golden hamster oocyte maturation, influencing nuclear and cytoplasmic development. Disruptions in MF structure, particularly in vitro, correlate with reduced fertilization rates.
Area of Science:
- Reproductive Biology
- Cell Biology
- Developmental Biology
Background:
- Microfilaments (MF) are essential cytoskeletal components involved in various cellular processes.
- Oocyte maturation is a complex process involving significant cellular reorganization.
- Understanding MF dynamics is key to improving in vitro maturation techniques.
Purpose of the Study:
- To investigate the localization and dynamic changes of microfilaments during golden hamster oocyte maturation.
- To correlate microfilament alterations with nuclear and cytoplasmic maturation events.
- To assess the impact of microfilament disruption on oocyte developmental potential.
Main Methods:
- Immunofluorescence microscopy was employed to visualize microfilament distribution.
- Confocal laser scanning microscopy (CLSM) provided high-resolution imaging of oocytes.
- Oocytes were matured both in vivo and in vitro, with specific experimental manipulations (e.g., cytochalasin D, hypoxanthine).
Main Results:
- Generalized submembranous MF were observed during in vivo maturation, concentrating near the first polar body extrusion site.
- A significant percentage (43.7%) of in vitro matured oocytes lacked submembranous MF, potentially explaining lower fertilization rates.
- MF were absent in follicular oocytes treated with cytochalasin D, inhibiting polar body extrusion.
- Oocytes arrested at the germinal vesicle stage synthesized submembranous MF, suggesting a role in nuclear progression.
Conclusions:
- Microfilaments play a critical role in regulating nuclear behavior during oocyte maturation.
- Differences exist between nuclear progression and microfilament dynamics.
- Microfilaments are likely involved in oocyte cytoplasmic maturation, though further research is needed.