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Updated: May 16, 2026
Single Oocyte Bisulfite Mutagenesis
Published on: June 27, 2012
DNA methylation pattern in mouse oocytes and their in vitro fertilized early embryos: effect of oocyte vitrification
Ying Liang1, Xiang-Wei Fu1, Jun-Jie Li1
1Laboratory of Animal Embryonic Biotechnology, College of Animal Science and Technology, and State Key Laboratories for Agrobiotechnology, China Agricultural University, Beijing 100193, People's Republic of China.
Abstract:
This study was conducted to investigate the pattern of DNA methylation in vitrified-thawed mouse oocytes and their in vitro fertilized early embryos. Firstly, mouse oocytes at metaphase II (MII) stage of meiosis were allocated randomly into three groups: (1) untreated (control); (2) exposed to vitrification solution without being plunged into liquid nitrogen (toxicity); or (3) vitrified by open-pulled straw (OPS) method (vitrification). Oocytes from all three groups were fertilized subsequently in vitro. The level of DNA methylation in the MII oocytes and their early embryos was then examined by immunofluorescence using an anti-5-methylcytosine (anti-5-MeC) monoclonal antibody and fluorescein isothiocyanate (FITC)-conjugated goat anti-mouse IgG. Developmental rates to 2-cell embryos (62.28%) and blastocysts (43.68%) of the vitrified-thawed oocytes were lower (P < 0.01) than those of fresh oocytes (81.47%, 61.99%) and vitrification solution treated (79.20%, 60.04%) oocytes. DNA methylation (as reflected by 5-MeC fluorescence intensity) in the vitrification group was less (P < 0.01) for MII oocyte and 2- to 8-cell stages compared with that in the control and toxicity groups. Accordingly, a reduction in global genomic methylation due to vitrification of MII oocytes may result in compromised in vitro developmental potential in early mouse embryos.
Insights
Vitrification significantly reduces DNA methylation in mouse oocytes and early embryos, compromising their developmental potential. This epigenetic alteration impacts embryo development after thawing.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Epigenetics
Background:
- Oocyte cryopreservation is crucial for assisted reproduction.
- Vitrification is a common cryopreservation technique.
- Epigenetic modifications, like DNA methylation, are vital for development.
Purpose of the Study:
- To investigate the impact of vitrification on DNA methylation patterns in mouse oocytes and early embryos.
- To assess the relationship between DNA methylation changes and developmental potential post-vitrification.
Main Methods:
- Mouse oocytes at metaphase II were divided into control, toxicity, and vitrification groups.
- Vitrification was performed using the open-pulled straw (OPS) method.
- DNA methylation levels were assessed using anti-5-methylcytosine (5-MeC) immunofluorescence.
Main Results:
- Vitrified-thawed oocytes showed significantly lower developmental rates to 2-cell and blastocyst stages compared to controls.
- DNA methylation levels (5-MeC fluorescence) were reduced in vitrified MII oocytes and early embryos.
- A significant decrease in DNA methylation was observed in the vitrification group versus control and toxicity groups.
Conclusions:
- Vitrification of mouse oocytes leads to a reduction in global genomic methylation.
- Compromised DNA methylation due to vitrification may negatively affect the in vitro developmental potential of early mouse embryos.
- Further research is needed to understand the long-term epigenetic consequences of oocyte vitrification.
