Mouse Sperm Cryopreservation Using Cryoprotectant Containing Monothioglycerol (MTG).

Significant progress has been made in sperm cryopreservation. It is now possible to achieve more consistent fertilization rates using in vitro fertilization (IVF) with cryorecovered sperm. Including the antioxidant monothioglycerol (MTG) in the cryoprotectant may increase the fertilization rate. This protocol has been successfully used at The Jackson Laboratory since 2007 to cryopreserve >5000 strains on many genetic backgrounds. Although it is possible to recover motile sperm from 2-yr-old mice, sperm quality often begins to decline by 6 mo of age. In practice, sperm from males 10-16 wk of age has yielded the best results. This protocol is relatively easy to implement because it uses a simple freezing apparatus and a cryopreservation medium.