Skip to main content

Importing Mouse Lines

Northwestern University investigators have several options for for importing new mouse lines. Mouse lines can be imported as:

  • Cryopreserved material: embryos or sperm
  • Live embryos sent overnight within the United States
  • Freshly isolated epididymis shipped under in cold conditions
  • TTML provided sperm cryopreservation kit
  • Live mice for rederivation


The process of rederivation eliminates pathogens such as pinworm, parvovirus, and mouse hepatitis virus from infected mouse lines. Pre-implantation embryos, which are relatively resistant to such pathogenic microorganisms due to the physical barrier of the zona pellucida surrounding the embryo, are collected from infected mice and washed through several droplets of embryo culture media, then surgically transferred into specific pathogen-free pseudopregnant females. Resulting mice can then be transferred to the barrier-level vivarium in the Lurie Research Center. Rederivation allows the import of established mouse lines with either known pathogens or of unknown health status from anywhere in the world.

 Prior to Scheduling

The Center for Comparative Medicine must initially approve the receipt of all animals into the vivarium.

Submit an Animal Import request to CCM and they will:

  • Assess the health status of the requested animals
  • Determine whether rederivation is necessary
  • Provide options for receiving the mice

If opting to have the TTML rederive the line, complete and return the Rederivation Request form, and we will:

  • Review the information
  • Contact CCM to schedule the shipping of the animals (Note: projects will be completed faster if two to three males are available)

 The Rederivation Process

  • Animals are received and housed in containment; males are singly housed upon arrival: tail samples will be taken and provided to verify genotype of received mice
  • Wild-type females are purchased and mated with males
  • Embryos are surgically transferred to SPF recipient mothers
  • Litters are born 19 days following surgical transfer
  • Tail tissue will be provided from 2- to 3-week-old pups for genotyping, if necessary: results are expected within one week
  • Blood for pathogen testing is collected from the mothers when pups are weaned
  • Rederived pups are transferred to your specified animal room

 Expected Results

  • Timeline is dependent on the number and fertility of the males received
  • Males are single housed upon arrival and allowed to acclimate for a week before mating with wild-type females
  • Males are mated for two consecutive weeks, which generally yields enough embryos for rederivation
  • Pathogen testing results are usually obtain within one to two weeks

 Your Responsibilities Following Rederivation

Once pups are weaned and pathogen testing results are received, TTML will initiate the transfer of these mice to your animal room and protocol.


Services include:

  • Coordination of animal receipt
  • Ordering and preparation of female donors/SPF recipients
  • Mating, collection and surgical transfer of embryos
  • Ear tag and tissue biopsy of 2- to 3-week-old pups, genotyping results expected within one week
  • Bleeding of recipient females; pathogen testing
  • Transfer of SPF pups to your protocol


View our core's pricing to get detailed information.

Costs include the purchase of wild-type mice used for the project; the housing of the surrogate females; and limited housing of weaned pups.

Investigators are responsible for the following costs:

  • Shipping costs: all purchase and shipping costs required to obtain males/ship SPF pups
  • Housing costs:
    • Per diems for the mice housed in containment for the duration of the project
    • Per diems will be charged once pups are weaned
  • Pathogen testing: all costs associated with additionally required testing

Follow Center for Genetic Medicine on