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document
Successful production of piglets derived from expanded blastocysts vitrified using a micro volume air cooling method without direct exposure to liquid nitrogen . This study was conducted to clarify the feasibility of newly developed vitrification techniques for porcine embryos using the micro volume air cooling ( MVAC ) method without direct contact with liquid nitrogen ( LN₂ ) . Expanded blastocysts were vitrified in a solution containing 6 M ethylene glycol , 0.6 M trehalose and 2 % ( wt/vol ) polyethylene glycol in 10 % HEPES-buffered PZM-5 . The blastocysts were collected from gilts and vitrified using the new device ( MVAC ) or a Cryotop ( CT ) . Blastocysts were stored in LN₂ for at least 1 month . After warming , cryoprotective agents were removed using a single step . Survival of the embryos was assessed by in vitro culture ( Experiment 1 ) and by embryo transfer to recipients ( Experiment 2 ) . In Experiment 1 , the embryos vitrified by the MVAC or CT and fresh embryos without vitrification ( Control ) were used . The survival rates of embryos in the MVAC , CT and Control groups were 88.9 % ( 32/36 ) , 91.7 % ( 33/36 ) and 100 % ( 34/34 ) , respectively , after 48 h culture , and the hatching rates of embryos after 48 h incubation were 69.4 % ( 25/36 ) , 63.9 % ( 23/36 ) and 94.1 % ( 32/34 ) , respectively . In Experiment 2 , 64 vitrified embryos were transferred to 5 recipient gilts , and 8 healthy piglets were produced from 3 recipients in the MVAC group . Similarly , 66 vitrified embryos were transferred to 5 recipient gilts , and 9 healthy piglets were produced from 2 recipients in the CT group . These results indicated that porcine expanded blastocysts can be cryopreserved using the MVAC method without potential pathogen contamination from LN₂ .
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Intervention_Physical
micro volume air cooling method
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Intervention_Physical
micro volume air cooling ( MVAC )
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Outcome_Other
production
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Outcome_Other
hatching rates of embryos after 48 h incubation
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Participant_Condition
piglets