The following table demonstrates basic differences between cryopreservation of sperm and embryos.

Embryo Freezing

Gamete (sperm & ovary)

Initial labour

Can take a few months to acquire all the embryos for storage.

Work is done in one day

Initial costs

As charges are dependant on the number of females used, costs will vary for each strain. Is more expensive than gamete freezing

Set cost.

Cheaper than embryo freezing

Numbers cryostored

Het X WT matings= 500

Het x Het matings=300

Homo X WT= 250

Homo X Homo= 250

Collect sperm from 3-5 males, so there are millions

Test thaw

Thaw assesses viability to live births.

Thaw assesses only motility. After freezing/thaw need an IVF session to determine live birth viability. More expensive than embryo freezing

Rederivation

Set cost for rederivation per round. Involves embryo thaw and culture, then an embryo transfer. Cheaper and less labour intensive

Set cost for Mouse IVF per round. Requires donor priming, embryo collection, IVF and culture, then embryo transfer. More expensive and more labour intensive

Genotype/phenotype

When rederived the genotype and phenotype of the resulting progeny will be exactly same as when freezing done.

Only cryopreserves half of genetic make-up of the original strain/background. Future rederivation can only produce a Het (due to IVF with WT eggs).