Related Experiment Video
Updated: Sep 23, 2026
Mouse Oocyte In Vitro Maturation, Fertilization, and Culture of Preimplantation Embryos
Published on: May 29, 2026
Induced cell death of preimplantation mouse embryos cultured in vitro evaluated by comet assay
Dusan Fabian1, Pavol Rehák, Sona Czikková
1Institute of Animal Physiology, Slovak Academy of Sciences, Soltésovej 4, 040 01 Kosice, Slovak Republic.
Abstract:
The occurrence of apoptosis in mouse preimplantation embryos was analyzed using DNA staining (Hoechst 33342, PI) for the visualization of nuclear changes and by the comet assay, a single-cell gel electrophoresis assay, modified for the analysis of blastocysts. Mouse preimplantation embryos isolated 56 h after superovulation were cultured in vitro for 64 h. Apoptosis was induced by treatment with camptothecin and actinomycin D during the first 15 h of culture. After culture in vitro, a number of embryos were stained and analyzed using morphological criteria. The remaining embryos were examined using the comet assay for the detection of DNA fragmentation. The proportion of damaged embryos in experimental groups, in comparison to controls, was dependent on the dose of apoptosis inductor. At high doses (camptothecin, microg/ml and actinomycin D, 0.05 microg/ml) over 90% (chi-square test, P<0.001) of embryos had apoptotic comets, at medium doses (camptothecin, 0.01 microg/ml and actinomycin D, 0.005 microg/ml) comets appeared only in 30-70% of embryos (camptothecin, P<0.01 and actinomycin D, P<0.001). At low doses (camptothecin, 0.001 microg/ml and actinomycin D, 0.0005 microg/ml) the increase in damaged embryos was not statistically significant. Hoechst/PI staining showed a higher percentage of damaged blastomeres at high doses. Morphological changes correlated with the outcome of the comet assay. Our results show that comet assay is an appropriate method for studying apoptosis in preimplantation embryos, and it appears to be more sensitive than the classically used morphological analyses.
Insights
The comet assay effectively detects apoptosis in mouse preimplantation embryos, showing higher sensitivity than morphological analysis for identifying DNA fragmentation and cellular damage.
Area of Science:
- Developmental Biology
- Cell Biology
- Reproductive Science
Background:
- Apoptosis, or programmed cell death, is crucial for normal embryonic development.
- Assessing apoptosis in early-stage embryos is vital for understanding developmental abnormalities.
Purpose of the Study:
- To evaluate the comet assay's efficacy in detecting apoptosis in mouse preimplantation embryos.
- To compare the sensitivity of the comet assay with traditional morphological analysis for apoptosis detection.
Main Methods:
- Mouse preimplantation embryos were cultured in vitro and apoptosis was induced using camptothecin and actinomycin D.
- Apoptosis was assessed using DNA staining (Hoechst 33342, PI) and a modified comet assay for blastocysts.
- Embryos were analyzed for nuclear changes, DNA fragmentation, and morphological alterations.
Main Results:
- The comet assay detected dose-dependent apoptosis induction by camptothecin and actinomycin D.
- Over 90% of embryos showed apoptotic comets at high inducer doses, significantly higher than controls.
- The comet assay demonstrated greater sensitivity in detecting DNA fragmentation compared to morphological assessments.
Conclusions:
- The comet assay is a suitable and sensitive method for studying apoptosis in preimplantation embryos.
- This technique offers advantages over traditional morphological criteria for apoptosis evaluation in early development.
