Assisted Reproduction

Rederivation by Embryo Transfer

To allow mice or rats from conventional housing or those with known or suspected pathogens to be brought into a barrier facility by embryo transfer. "Dirty" male mice/rats are held in quarantine where they are mated with donor females. Embryos from these matings are washed and transferred to clean surrogate mothers in TGEF's barrier facility. At weaning, surrogate mothers are bled and serum prepared and shipped for serological testing. Once the pups are confirmed pathogen­ free, they will be transferred to the investigator's animal facility. 

Embryo Cryopreservation

To preserve valuable lines of mice and rats for security and to avoid costly long-term maintenance of breeding colonies. Valuable germplasm is cryopreserved as embryos and stored in straws immersed in liquid nitrogen. The investigator will provide 7-8 males who will be mated multiple times with wild type females supplied from TGEF’s in-house colony. Investigator-provided females may be utilized for an additional fee and after consultation with the TGEF director on breeding strategy. 300 embryos (200 for rats) will be collected from the females and frozen. Frozen embryos can later be thawed and transferred into surrogate mothers when they are needed, either for research or to replace contaminated or infected lines. There is a yearly storage fee for each line stored in TGEF’s duplicate cryobanks. 

Sperm Cryopreservation

To preserve sperm from valuable lines of mice for security and to avoid costly long-­term maintenance of breeding colonies. Valuable germplasm is collected from 2 males, cryopreserved and stored in straws immersed in liquid nitrogen. Sperm can later be thawed and used for IVF to repopulate the colony when needed, either for research or to replace contaminated or infected lines. There is a yearly storage fee for each line stored in TGEF’s duplicate cryobanks. At this time, only available for mice. 

In Vitro Fertilization

To overcome breeding problems in valuable mice. Transgenic or otherwise valuable mice frequently encounter breeding problems related to genetic manipulation, in-breeding or simply age. This technique allows investigators to save lines of mice which would otherwise be lost. Sperm is collected from the mouse in question and incubated with unfertilized oocytes from donor females. Successfully fertilized eggs are then transferred to surrogate mothers who give birth to offspring of the original infertile male. This technique is also used to regenerate lines from frozen sperm. At this time, only available for mice. 

Speed (Embryo) Cryopreservation

Same as Embryo Cryopreservation above, but utilizing IVF and only 2 males, to quickly generate the 300 embryos necessary to secure the line. At this time, only available for mice. 

Speed Expansion

To rapidly produce a large number of mice using IVF. Sperm is collected from 2-­3 male mice of the line required and incubated with oocytes from wild type donor females. Successfully fertilized eggs are transferred to surrogate mothers who give birth to offspring of the original male. At this time, only available for mice.