Chromosome abnormalities and viability of vitrified eight-cell mouse embryos at presence of two different cryoprotectants at different storage durations

ABSTRACT

Experiments were conducted to find the differences between post-thaw viability and chromosome aberrations in eight-cell mouse embryos at presence of dimethyl sulfoxide [DMSO] and 1, 2-propanediol [PROH] as croprotectants in different storage durations. In this case-control study, a total number of 720 mouse embryos from about 250 NMRI mice were vitrified with 30% PROH or DMSO; each diluted with a solution containing 30% ficol plus 0.5 M sucrose. Embryos were exposed to the solutions for 0.5 minute at 25[degree sign] followed by cooling in liquid nitrogen, then after appropriate storage duration, they were rapidly warmed. Besides, there were 100 mouse embryos for each cryoprotectant group [totally 200 embryos] as control. Embryo survival was assessed by in vitro development, and chromosome abnormalities were analyzed by Giemsa staining. The proportion of mitotic abnormalities in PROH/DMSO vitrified embryos was significantly higher than unfrozen control group. This was confirmed also by a reduced viability of the embryos as judged by a culture at the blastocyst stage [p<0.05 in all test groups]. It can be deduced that long term cryopreservation may result in chromosomal abnormalities and/or low viability