Lay Summary: The high numbers of embryos produced, manipulated and cryopreserved for research involving genetically altered animals requires that large numbers of embryo transfers are carried out in mice. At the NIMR, each of our transgenic technicians carries out in the region of 500 to 1000 transfers per year. The mice are anaesthetised and embryos are surgically implanted in the uterus or oviduct depending on their stage of development. We tested whether non-surgical transfer through the cervix, was a viable and effective alternative.
Non-surgical embryo transfer of blastocysts through the cervix of mice is a viable and effective alternative to surgical transfer with comparable live birth rates after practice. The most effective technique is to use the NSETTM device to insert blastocysts through the cervix of an E2.5 pseudopregnant mouse that is conscious, and either scruffed or placed on a cage roof, although using gaseously anaesthatised mice is also effective especially to those new to the technique. This method involves a significant reduction in the severity of the procedure to the animal, and also time and economic savings, cutting out the need for analgesia, anaesthesia and surgery for the mice. We have now swapped over to this technique for our work with ES cells and blastocysts in mice, cutting our surgical work significantly. We feel the technique is of particular importance considering the increasing amount of gene targeted work being carried out, which specifically requires blastocyst embryo transfer.
This method has been presented at several meetings for the NC3Rs, LASA, LAVA and RSPCA, aimed at veterinarians, transgenic and animal technicians, with good responses and I have integrated it into 2 annual courses covering best practice in colony management, run by the Wellcome trust and in a "Transgenics and the 3Rs" workshop, run by the RSPCA. Uptake of the technique across the UK has been high, and we have support from the HOI. I will continue to disseminate this work, it has been published elsewhere, but we are working on some refinements and hope to transfer the technique to rats. We are also looking to produce a video advising best practice in the technique to be available on the web.
Scientific Abstract: The large numbers of embryos produced and cryopreserved for research into genetically altered animals, requires that large numbers of embryo transfers are carried out in mice. At the NIMR, each of our transgenic technicians carries out in the region of 500 to 1000 transfers per year. The mice are anaesthetised and embryos are surgically implanted in the uterus or oviduct depending on their stage of development. We want to test whether non-surgical transfer through the cervix, is a viable and effective alternative. This could change the severity of the procedure to cut out surgery, and possibly even anaesthesia, by using a method similar to that which we use for artificial insemination.