Potential of two-cell mouse embryos to develop to term despite partial damage after cryopreservation

Area of Science:

• Reproductive Biology
• Embryology
• Cryopreservation Science

Background:

• Cryopreservation of 2-cell mouse embryos is a standard practice in reproductive biology.
• Morphological assessment is crucial for selecting viable embryos for transfer.
• The impact of freeze-thaw damage on embryo development requires further investigation.

Purpose of the Study:

• To evaluate the viability and developmental potential of cryopreserved 2-cell mouse embryos exhibiting morphological damage.
• To assess the survival rate of blastomeres after cryopreservation and thawing.
• To compare the in vitro and in vivo developmental outcomes of intact versus partially damaged embryos.

Main Methods:

• Cryopreservation of 26 batches of 2-cell mouse embryos.
• Morphological assessment using light microscopy.
• Vital staining (Fluorescein-diacetate and 4', 6-Diamidino-2-Phenylindole) to determine blastomere survival.
• In vitro culture to blastocyst stage.
• Embryo transfer to foster mothers for assessment of term development.

Main Results:

• Approximately 18% of cryopreserved 2-cell mouse embryos showed morphological damage.
• Blastomere survival post-thaw was high, with 82% of embryos retaining both blastomeres.
• Over 60% of partially damaged embryos developed to blastocyst in vitro, and 26% of these developed to term after transfer.
• Despite smaller inner cell mass during culture, no differences in gestation period were observed compared to intact embryos.

Conclusions:

• A significant proportion of cryopreserved 2-cell mouse embryos can recover from morphological damage and achieve full term development.
• Vital staining is effective in assessing blastomere viability post-cryopreservation.
• Partially damaged embryos represent a viable option for embryo transfer, expanding the utility of cryopreservation techniques.