Large numbers of mice established by in vitro fertilization with cryopreserved spermatozoa: implications and applications for genetic resource banks, mutagenesis screens, and mouse backcrosses.

Recent advances in the methodologies for cryopreservation of mouse spermatozoa have opened up a number of opportunities for mouse geneticists. We have investigated various applications for this relatively new technology and have explored the potential of sperm freezing coupled with IVF for archiving, stock building, and the rapid establishment of backcrosses. Firstly, we investigated the use of sperm freezing for the archiving of (C3H/HeH x BALB/c)F(1) progeny from a large-scale mutagenesis program. We have demonstrated that it is possible to establish efficient, comprehensive, and deep archives and that potentially thousands of offspring can be derived from the frozen spermatozoa of a single mutant male mouse. Secondly, we examined the efficacy of sperm freezing for a number of other genotypes. For at least some genotypes, frozen spermatozoa can be utilized to rapidly build stock far more quickly than by conventional methods. Finally, we demonstrated that it is feasible to use frozen spermatozoa from the mouse mutant archive for the rapid generation of mutant backcross progeny.