Viability of frozen-thawed mouse blastocysts with different number of dead cells

Dead cells in frozen-thawed mouse blastocysts were detected by the DAPI-fluorescence test, and the relationship between the number of dead cells in the embryos and their in vitro development was examined. Morphologically good embryos had significantly fewer dead cells and gave a higher percentage of embryos that developed in vitro than the fair and poor embryos. Viability of the good embryos was reduced as the number of dead cells increased (P<0.001). Embryos with more than 5 dead cells had a very low viability of 7.1%. Embryos which showed re-expansion of the blastocoele after the removal of DMSO had significantly fewer (P<0.001) dead cells than those which remained contracted. The percentage of the re-expanded and contracted embryos that developed in vitro was 97.5 and 51.8%, respectively. These results indicate that number of dead cells influenced the in vitro development of frozen-thawed mouse blastocysts.