[Effect of fusion duration on cleavage and developmental rate of electrofused tetraploid 2-cell bovine embryo]

ABSTRACT

Because tetraploid embryo is used as a base for growth and development of transgenic cells, one of the most important stages in animal biotechnology is to produce tetraploidy by electrofused 2-cell embryo. The aim of this study was to determine the effect of fusion duration on developmental rate of tetraploid embryos. In this experimental study some of the bovine 2-cell embryos were obtained from in vitro matured and fertilized cumulus oocyte complexes 33-35 hr post fertilization as an unexposed control group [UCG]. The remaining 2-cell embryos were exposed to 0.75 kilovolt per centimeter for 80 microsecond, and were transferred to SOF1 medium. Subsequently those embryos fused at 30 and 60 minute post electrofusion were categorized as fused groups [FG[30] and FG[60]] and separated from unfused embryos as exposed control group [ECG]. The developmental rate was compared between UCG, ECG, FG[30], and FG[60] groups and the relation between fusion duration and cleavage and developmental rate was surveyed.The cleavage rate up to 8-cell stage in FG[60] was increased significantly compared to FG[30][p<0.05] while the blastocyst rate has no significant difference between the two groups. The cleavage and developmental rate in UCG was significantly higher than ECG, FG[60] and FG[30]. Chromosomal analysis showed that 76% of embryos were true tetraploid.The fused embryos in FG[60] had more ability to produce embryos up to 8-cell stage than FG[30]. The electrical pulse can decrease the cleavage and developmental ability of embryo