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Developmental potential of frozen-thawed human blastocysts
T Nakayama1, Y Goto, H Kanzaki
1Department of Gynecology and Obstetrics, Kyoto University, Faculty of Medicine, Japan.
Journal of Assisted Reproduction and Genetics
|April 1, 1995
Summary
Freezing human embryos at the blastocyst stage shows reduced developmental potential. Longer in vitro culture before freezing negatively impacts embryo development after thawing.
Area of Science:
- Reproductive medicine
- Embryology
- Cryobiology
Background:
- Cryopreservation of human embryos is a key technique in assisted reproductive technology.
- Assessing the developmental potential of embryos post-thaw is crucial for successful outcomes.
Purpose of the Study:
- To investigate the feasibility and outcomes of cryopreserving human embryos at late cleavage stages (morula or blastocyst).
- To evaluate the developmental potential of human embryos after thawing, specifically comparing those frozen at 5 versus 6 days post-insemination.
Main Methods:
- 119 morphologically good-quality human embryos from in vitro fertilization (IVF) treatments were cryopreserved using dimethyl sulfoxide.
- Embryos were cryopreserved for 5 to 30 months and then thawed.
- Post-thaw developmental potential was assessed through 24 hours of in vitro culture, with survival and developmental rates evaluated.
Main Results:
- Survival rates did not differ significantly between embryos frozen on day 5 (78.2%) and day 6 (70.0%).
- Developmental rates after thawing were significantly lower for embryos frozen on day 6 (6.0%) compared to day 5 (18.8%).
- Overall fetal development after transfer was low (1.7%).
Conclusions:
- The developmental potential of cryopreserved-thawed human blastocysts is significantly diminished, even with good initial morphology.
- Extended in vitro culture duration prior to cryopreservation appears to reduce the developmental capacity of human embryos.