Genetic banking through the use of mouse embryo cryopreservation is a practical means to store scientifically valuable mice. Mouse embryos stored in liquid nitrogen offer a safe way to preserve lines with potential future use but no current use and offer savings in facility space and the expense associated with keeping a breeding colony. Another advantage is that during the process of embryo collection, most pathogenic organisms are excluded as in other methods used to rederive lines of mice.
Briefly, the procedure entails harvesting embryos from donor females at the 8-cell developmental stage that is optimal for cryopreservation by our method. A controlled-rate methanol bath freezer is used to gradually cool the embryos to -80°C, before plunging them into liquid nitrogen for storage. Quality control is assured by freezing and thawing a representative sample of wild-type frozen embryos along with each line frozen down. Frozen embryos should be retrieved by the investigator one week post-freezing for long-term storage in liquid nitrogen in the investigator's own lab.
- Client coordinates the receipt of at least 8 to 9 males preferably homozyogous for transgene, ages between 2 to 5 months, of desired strain into the Rodent Isolation Unit (RIU) with the Animal Care Program Acquisitions Office.
- Core acquires wild-type females of the appropriate background strain and schedules procedure
- Core super-ovulates and RIU personnel mate females with males in RIU
- Core collects embryos, and freezes them.
- Core will freeze up to 200 embryos per line (if homozygous males provided) and 250 embryos per line ( if heterozygous males provided)
- Core will store vials for up to 1 week. Client does long-term storage in liquid N2