Accepted_test
Among mammals, obligate embryonic diapause (ED), i.e. suspension of embryo development at the blastocyst stage, occurs in no less than 60 species belonging to 12 families. Normally obligate ED disentangles breeding season and the offspring birth, thus evolutionally perpetuate the species. The goal of this work was to develop reproductive technologies for diapausing embryos using the mouse as an experimental model. All the diapausing embryos collected were at blastocyst stage. Total number of diapausing blastocysts cryopreserved was 160 (11 replicates). The post-thaw embryo viability was assessed by different criteria; all of the criteria indicated that the diapausing murine embryos survived cryopreservation. The increase of cells in the frozen-thawed embryos after in vitro culture in a medium containing putrescine is strong evidence of their viability. Meanwhile, our study revealed that diapausing embryos need re-activation time to resume cell division after freezing-thawing procedures. To expand embryo cryopreservation technology to other mammalian species, which possess ED, the evolutional difference in diapause phenotype between species of mammals should be taken into account.