Cryopreservation: Live Embryos

Cryopreservation of embryos is a routine method of archiving mouse strains for future use as well as a recommended way to safeguard against infection in a breeding colony. Unlike spermfreezing and revival with IVF, where heterozygotes are produced, the pups derived from reviving frozen embryos have the exact genotype they had when they were frozen, this method is therefore ideal for homozygous conservation of single, but even more so, double and triple transgenics.

We use the CARD protocol for cryopreserving 2-cell stage embryos. The embryos will be stored in cryovials within liquid N₂ containing 30-40 embryos each. By default we will use fertilised oocytes at the 2-stage embryo phase, however we are able to accommodate other cell-stages by request.

We recommend freezing at least 200 embryos to optimise future strain revival and to have extra vials for sharing with collaborators. To achieve this we will require 10 – 15 males of breeding age. Where possible we recommend the use of 3-4 week old C57BL/6 females (provided by us) to be mated with transgenic males to produce heterozygous embryos. In cases where homozygous embryos are required, the number of females needed is dependent on the age, embryo yield, embryo viability and mating success of the strain. For these reasons we recommend sending initially 20 females, but more may be required. If you are unable to provide enough females we offer the option to have the mice bred at our facility at an additional breeding and maintenance fee of 700 CHF.

For information about subsequent embryo transfer implantation at our facility please refer to: Embryo Transfer 

1. A completely filled out request form
2. The GMO datasheet as requested by the veterinary office
3. 10-15 transgenic males
4. For homozygous embryos, at least 20 females or 2 breeding pairs for our in house breeding
5. For heterozygous embryos we will provide the females

Cryopreservation of 200-300 heterozygous embryos: 2400 CHF*

Cryopreservation of 200-300 homozygous embryos: 2200 CHF

Breeding and maintenance fee (if required): 700 CHF

*includes cost of sufficient C57BL/6 female breeding partners for 200 embryos