Cryopreservation of in vitro cultured mouse preimplantation embryos.

We investigated two different freezing protocols on mouse embryos that were either grown in vivo or were grown in vitro for a certain period. Our results confirm that an extended in vitro culture period makes the embryo more susceptible for injury due to freezing and thawing. Furthermore when freezing two cell mouse embryos we could observe that this early stage is more dependent on optimal cryopreservation protocol parameters than later stages.