Reviving cryopreserved mouse embryos to re-establish a colony

Immunocompromised mouse strains may be archived by cryopreserving their germplasms in order to reduce facility space usage and to protect the strains from losses due to environmental disaster, genetic drift, disease outbreak or breeding failure. Frozen embryos can then be revived and implanted into surrogate dams to expand the breeding stock if the need should arise. When Ingle and colleagues experienced a sudden breeding failure in their NOD–SCID mouse colony, they attempted to re-establish the colony from cryopreserved stock embryos instead of importing live mice. The authors describe how they successfully revived the frozen embryos from the institution's cryopreservation repository and confirmed that the recovered progeny lacked T and B cells.

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Availability of unsoiled resting areas in rodent cages

The Guide for the Care and Use of Laboratory Animals (the Guide) recommends that animals be provided sufficient space to comfortably rest away from areas soiled by urine and feces. To evaluate the feasibility of meeting this recommendation, Boivin examined over time the availability of feces-free resting areas in the cages of adult C57BL/6 mice and Wistar rats housed singly, in pairs or in trios in shoebox cages at densities that met the space recommendations of the Guide. The author concludes that the recommendation may not be a reasonable expectation and suggests that the benefit of unsoiled resting areas to animal welfare be further investigated.

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