The freezing of mature spermatozoa has become a viable alternative to embryo cryopreservation. Freezing sperm is more cost effective and less labor intensive than freezing embryos. Improved protocols developed by The Jackson Laboratories have improved previous methods of sperm cryopreservation and reconstitution.
Cryopreservation provides a safe path for preserving the quality and protection of the transgenic line for any potential projected future experiments. The investigator is responsible for providing a complete description of the mouse line to be cryopreserved (strain, genotype, etc.) Wildtype (purchased) female mice are superovulated and mated with a minimum of 8 heterozygous or 7 homozygous male stud mice between the ages of 2-6 months that are provided by the investigator. From these matings a minimum of 250 heterozygous or 150 homozygous embryos are harvested and cryopreserved.