Factors influencing the Yield of Transgenic Mouse Embryos for Cryopreservation

Cryopreservation of pre-implantation embryos is  a powerful tool to save and handle the increasing  number of transgenic mouse lines, often consisting  of very small populations. However, the outcome  of embryos following superovulation and mating  varies and is one of the limiting factors for  cryopreservation. Using the data received together  with the cryopreservation of more than 100,000  mouse embryos, the role of embryo yield limiting  and of yield raising factors was analyzed: annual  rhythms, seasonal changes (possibly due to  environmental effects, such as extreme weather  conditions), infections of a mouse colony, or the  mating frequency of males. Then again to increase  embryo yields two pheromonal effects were  investigated: Especially the housing of female  donors in small groups (Lee-Boot effect), but also  the exposure to the future males’ bedding two  days before mating (Whitten effect) resulted in  remarkably higher embryo yields.Â