Cryopreservation of Valuable Mouse and Rat Lines

The application of cryopreservation technologies to generate a cryobank of embryos and germ cells from genetically valuable mouse and rat lines is a standard procedure applied in many rodent facilities and large repositories around the world. Slow freezing was the first methodology developed for embryo cryopreservation and is still suitable and reliable. Despite this, the ultra-rapid vitrification technique is gaining more adepts since it is faster, consistent, and does not require expensive equipment. For sperm freezing, standardized protocols using commercial media are now available with excellent outcomes, reducing the number of donor animals required, the final cost, and ensuring the preservation for future in vitro fertilization. In this chapter, we will summarize the past, present, and future of the main techniques used nowadays and their benefits, with the aim to help readers understand the relevance to preserve the germplasm (i.e., spermatozoa, oocytes, and resulting embryos) of valuable lines.