The viability of deep-frozen cow embryos.
Day 7 cow embryos were frozen in 1.5 M-DMSO in PBS at 0.3 degrees C/min to -36 degrees C and at 0.1 degrees C/min between -36 and -60 degrees C before being plunged directly into liquid nitrogen. They were subsequently thawed (rapidly to -50 degrees C, at 4 degrees C/min from -50 to -10 degrees C, and rapidly again) to room temperature. Embryonic viability was tested by four different transfer techniques. Maximum pregnancy rate (8/12) was obtained with surgical transfer immediately after thawing and dilution of DMSO.
D000818:Animals; D002417:Cattle; D004624:Embryo Transfer; D004622:Embryo, Mammalian; D005615:Freezing; D014021:Tissue Preservation / Q000379:methods*; D014022:Tissue Survival