Survival of Mouse Embryos Frozen to -196° and -269°C

TLDR

Survival of mouse embryos at cryogenic temperatures required slow cooling (0.3–2 °C/min) and slow warming (4–25 °C/min). Mouse embryos survived freezing to –196 °C, with 50–70 % forming blastocysts after up to 8 days storage, and when ~1,000 survivors (some frozen to –269 °C) were transferred, 65 % of recipients became pregnant and over 40 % of embryos produced normal full‑term pups.

Abstract

Mouse embryos survived freezing to -196°C. Survival required slow cooling (0.3° to 2°C per minute) and slow warming (4° to 25°C per minute). Depending on the specific rates used, 50 to 70 percent of more than 2500 frozen and thawed early embryos developed into blastocysts in culture after storage at -196°C for up to 8 days. When approximately 1000 of the survivors, including some frozen to -269°C (4°K), were transferred into foster mothers, 65 percent of the recipients became pregnant. More than 40 percent of the embryos in these pregnant mice gave rise to normal, living full-term fetuses or newborn mice.