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Meredith Harrell

Viability of 1-cell embryo cryopreservation in Mus musculus

Harrell Meredith; Landrock Danilo; Kier Ann

Department of Veterinary Pathobiology, Texas A&M University College of Veterinary Medicine and Biomedical Sciences, College Station, Texas, USA

Meredith Harrell

Objective – To determine the viability of mouse embryo cryopreservation at the 1-cell stage as compared to previous viability data from the standard 8-cell stage cryopreservation as measured by in vitro culture and pups born.

Animals or Sample Population – Twenty-three inbred C57/BL6 mice were used for embryo donations and six outbred Swiss Webster females were used as recipient females.

Procedure – Female embryo donors underwent superovulation treatment and mating.  Embryos were isolated and removed from donors and put through a cryopreservation freezing/thawing cycle.  After cryopreservation, embryos were incubated overnight to ensure progression to the 2-cell stage and only those embryos exhibiting normal morphology were implanted into recipient females for development.  Recipient females were monitored for pregnancy and number of live pups born.

Results – A total of 252 fertilized embryos underwent cryopreservation.  Of these, 78.6% showed progression to the 2-cell stage after recovery.  Embryos cultured in vitro showed a 76.2% progression to the 8-cell stage and 69.1% progression to the blastocyst stage.  In vivo, 160 embryos were implanted into 6 recipient females.  Five females became pregnant and >23* live pups were born (*exact number unknown due to cannibalization by one female).

Conclusions and Clinical Relevance – One-cell stage embryo cryopreservation is possible using existing protocol and 1-cell embryos show comparable efficiency to the 8-cell stage cryopreservation.  Further study is now needed to determine if the 1-cell stage is more resistant to pathogens than the 8-cell stage.