The effects of cryopreservation on early development and chromosome constitution in Chinese hamster embryos

The effects of cryopreservation on early embryonic development were investigated in Chinese hamster embryos. Embryos were randomly divided into 3 groups, as follows: the control group, embryos which were simply cultured; the DMSO group, embryos which were exposed to dimethyl sulfoxide (DMSO) and then cultured; the cryopreservation group, embryos which were cryopreserved and then cultured. The percentages of embryos which developed into blastocysts after 40 hours of cultivation were high in all groups. However, there were significant differences in the mean number of blastomeres with lower values after an exposure to DMSO and cryopreservation (73.2 in the control group, 62.0 in the DMSO group, and 40.2 in the cryopreservation group). No significant differences in chromosome abnormality rate were evident and there was no distinct tendency for variation in karyotype among the 3 groups. These results indicate that DMSO adversely affects the division of blastomeres, and that cryopreservation with DMSO as a cryoprotectant might aggravate these adverse effects.