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Updated: Aug 21, 2026
Human Egg Maturity Assessment and Its Clinical Application
Published on: August 19, 2019
Spindle dynamics in living mouse oocytes during meiotic maturation, ageing, cooling and overheating: a study by
Xiao-Fang Sun1, Wen-Hong Zhang, Xin-Jie Chen
1Guangzhou Medical College, Guangzhou, China and Houston Fertility Institute, Tomball, Texas, USA.
Abstract:
A liquid crystal polarized light microscope (LC PolScope) was used to examine spindle dynamics in living mouse oocytes. Immature oocytes were cultured for 0-48 h and spindles were imaged with the PolScope at various time points of culture. Oocytes at metaphase I (M-I) and metaphase II (M-II) were also exposed to shifts of temperature from 25 to 41 degrees C to examine the effects of fluctuations of temperature on spindle dynamics. After examination with the PolScope, some oocytes were fixed and examined by immunocytochemical staining and confocal microscopy. After culturing for 6 h, 76% and 2% of the oocytes reached M-I and M-II stages and all oocytes had birefringent spindles. When the oocytes were cultured for 14-16 h, 88% and 6% of oocytes were at M-II and M-I stages respectively and all oocytes had birefringent spindles. However, when the oocytes were cultured for 22-48 h, the proportions of oocytes with birefringent spindles decreased as culture time was increased. Exposure of oocytes to 25 degrees C induced spindle disassembly within 10-20 min in both M-I and M-II oocytes. Most (93-100%) oocytes reassembled spindles after warming at 37 degrees C. Furthermore, exposure of oocytes at M-I stage but not at M-II stage, to 30 degrees C also induced significant microtubule disassembly. However, exposure of oocytes to 38-41 degrees C did not obviously change the quantity of microtubules in the spindles, which was measured by retardance. This study indicates that the PolScope can be used to examine spindle dynamics in living oocytes, and it has the advantage over the routine fluorescence microscope in that images can be obtained in the same individual oocyte and the quantity of microtubules can be measured by retardance in living oocytes. These results also indicate that the M-II spindle in mouse oocytes is sensitive to oocyte ageing and cooling, but not heating, and M-I spindle is more sensitive to temperature decline than M-II spindle.
Insights
The liquid crystal polarized light microscope (LC PolScope) effectively visualizes spindle dynamics in mouse oocytes. Mouse oocyte spindles are sensitive to cooling and aging but not to moderate heating.
Area of Science:
- Cell Biology
- Reproductive Biology
- Microscopy
Background:
- Spindle dynamics are crucial for accurate chromosome segregation during meiosis.
- Understanding spindle behavior in oocytes is essential for reproductive success and fertility research.
- Traditional microscopy methods have limitations in assessing dynamic spindle changes in living cells.
Purpose of the Study:
- To evaluate the utility of the liquid crystal polarized light microscope (LC PolScope) for examining spindle dynamics in living mouse oocytes.
- To investigate the effects of culture time, aging, and temperature fluctuations on meiotic spindle structure and stability in mouse oocytes.
Main Methods:
- Living mouse oocytes were cultured for up to 48 hours and imaged using the LC PolScope.
- Oocytes at metaphase I (M-I) and metaphase II (M-II) were subjected to temperature shifts (25°C to 41°C).
- Immunocytochemical staining and confocal microscopy were used for post-examination validation.
Main Results:
- The LC PolScope successfully visualized birefringent spindles throughout oocyte maturation.
- Spindle birefringence decreased with extended oocyte culture (22-48 hours), indicating age-related instability.
- Cooling to 25°C induced spindle disassembly in both M-I and M-II oocytes, with rapid reassembly upon warming to 37°C; M-I spindles were more sensitive to cooling than M-II spindles.
Conclusions:
- The LC PolScope offers advantages over fluorescence microscopy for real-time spindle dynamics analysis and microtubule quantification in living oocytes.
- Mouse oocyte spindles are sensitive to aging and cold temperatures, with M-I spindles being more vulnerable to temperature decline.
- Moderate heating (38-41°C) did not significantly affect spindle microtubule quantity, suggesting a degree of thermal resilience.
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