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Mouse Embryo and Spermatozoa Cryopreservation

​21-24 September 2015

Intended to give animal technologists practical, hands-on experience of the murine embryo and spermatozoa freezing techniques routinely used at MRC Harwell, as well as a simple, robust in vitro fertilization procedure.

Cryopreservation allows long-term storage of embryos and sperm, providing a convenient way to preserve, protect and transport mouse lines for use in research. Here at MRC Harwell we have extensive experience of using cryopreservation techniques. By providing this course we aim to share our expertise with the wider scientific community. It is supported by the European Mouse Mutant Archive (EMMA).

The course runs over a period of three and a half days, this year from 2-5 March and 21-24 September, and is worth ten continuing professional development (CPD) points. It is led by MRC Harwell’s Frozen Embryo and Sperm Archive (FESA), part of the European Mutant Mouse Archive (EMMA), a collective effort by centres all across Europe to create a genetic archive for use by the international scientific community.

Day 1: participants learn how to freeze sperm in liquid nitrogen using plastic semen straws. While embryos can be stored ready to use, sperm cryopreservation has the advantage that, as long as you have enough oocytes for fertilisation, you can potentially recover over a thousand mice from the sperm of just one male.

Day 2: embryo cryopreservation. The embryos were harvested, loaded into straws and frozen in the morning, and after lunch the group learnt how to thaw them out again. At the end of the day, everyone had the chance to get to know each other a little better at the course dinner.

Days 3 and 4: participants gain experience of a straightforward and robust in vitro fertilisation (IVF) procedure, with a demonstration of how these embryos can then be transferred into recipient females to establish a new pregnancy. The course concludes with a final review and recap.

In this way, the course allows participants to gain experience of the entire process, from harvesting the embryos and sperm, to conducting IVF and transferring embryos into the female mouse.

Please contact the course convenor Martin Fray ( for more details or email