Depending on their housing and transportation conditions mouse strains may be carrying a multitude of pathogens that may or may not result in disease but may very well affect your experimental result outcomes. The APF can “rederive” your strain to remove these unwanted pathogens and provide your strain with a Specific Pathogen Free status.
The rederivation process
Achieved by sperm cryopreservation and IVF or by live mating. Both employ harvesting of 2-8 cell embryos, washing them in sterile media and transferring them into the oviduct of pathogen-free, pseudo-pregnant females resulting in the birth of specific pathogen-free offspring.