In vitro fertilisation (IVF) is used to re-animate strains from the frozen state from sources such as the repository of the Australian Phenome Bank. The team is using the latest and most efficient IVF techniques and re-animation success is currently running at 97% of attempts with sperm thawed from the APB archive.
Incubation of the frozen-thawed sperm with oocytes harvested from females of the correct background. Resulting two-cell embryos are transferred into pseudo-pregnant females and if successful, pups will be born 20-21 days later.
Until recently, IVF with sperm and oocytes on the C57BL/6 background was notoriously difficult. A new IVF technique developed by Professor Naomi Nakagata and colleagues in 2012 allowed the APB to change their IVF procedure to one resulting in higher two-cell fertilisation efficiency for strains on C57BL/6 background. While strain-to-strain variation is still evident, the APB consistently achieves two-cell fertilisation efficiencies of more than 80 per cent.