Bioresources offers the ability to archive important mouse lines as embryos and/or sperm. Most lines can be cryopreserved as sperm, though embryo freezing is required for lines that must be maintained as homozygous or on a specific genetic background.
Although sperm cryopreservation requires fewer mice for freezing and is cheaper, revival of the line is more expensive than if embryos were initially frozen. Additionally, if shipping samples to collaborators, shipping embryos is often preferred to sperm as many facilities do not have the capability to perform IVFs.
Cryopreservation of Sperm
We require male that are at least 8 weeks old and ideally less than 6 months old. For each male, 8 straws of semen are frozen as well as 1 QC straw. Typically, 3 males per line are frozen.
A QC is performed on the sperm sample as part of the freezing charge. It involves thawing one straw and observing the level of sperm activity. There is no guarantee that the sperm sample is capable of successfully being used in an IVF, though in the majority of cases this will be so. There is no confirmation that the sperm sample carries the correct genotype.
Cryopreservation of Embryos
For embryo cryopreservation to be performed, 8-10 males of fertile age (8 weeks - 6 months) are required, unless the line must be maintained as homozygous or on a particular background, in which case 30-50 female mice aged 21-28 days will be required. Normally, Bioresources would manage any breeding to produce the female mice for this service, which would be included in your monthly cage charges.
Two levels of embryo cryopreservation are offered:
QC for Embryo Cryopreservation
10-20 embryos are thawed and cultured to the blastocyst stage to confirm viability.
Cryopreservation of Embryos and Sperm
This is the optimal way to archive a line as it affords the possibility of having sperm samples stored from 3 males as well as having 200 2-cell embryos stored in a discounted packaged deal. If for some reason IVF is not available (or not successful) then, from the bank of 200, there are always some embryos remaining to reanimate the line. If a collaborator requires the line, they can be sent either sperm or embryos depending on what capabilities they have at the receiving institute, when freezing as a package deal.
If cost is an issue, then sperm freezing at a minimum is recommended.
For further information, please contact firstname.lastname@example.org
If you want to discuss your specific requirements or are wanting to re-animate any cryopreserved sperm stored in the facility bank or from an external source, please contact our Rederivation/ Cryopreservation Coordinators: Faience Kramer (email@example.com) and Nicole Jeffries (firstname.lastname@example.org)