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Introduction: 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.
Materials and Methods: 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 (FG30 and FG60) and separated from unfused embryos as exposed control group (ECG). The developmental rate was compared between UCG, ECG, FG30, and FG60 groups and the relation between fusion duration and cleavage and developmental rate was surveyed. Results: The cleavage rate up to 8-cell stage in FG60 was increased significantly compared to FG30 (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, FG60 and FG30. Chromosomal analysis showed that 76% of embryos were true tetraploid.
Conclusion: The fused embryos in FG60 had more ability to produce embryos up to 8-cell stage than FG30. The electrical pulse can decrease the cleavage and developmental ability of embryo

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Introduction: Stirility is a problem throughout the world. Decreasing the growth and developmental rate of embryo and arresting in certain step of development like two cell block, could be the reason of infertility in some couples. Previous study show that arrest and retardation in embryo development can produced by low temperature exposure. We aimed to evaluate the effect of Ethanol on growth and development of mouse two-cell arrested embryo. Material and methods: The 4-6 week old female mice were coupled with male mice following superovulation and positive vaginal plaque mice were killed 48 hour after HCG injection by cervical dislocation method. Two cell embryo were collected in RPMI medium and divided and cultured (in M16 medium) in three groups. The 2nd and 3rd groups were exposed to 4°C for 24 hour in order to delay and arrest for cleavage and developmental rate. The 2nd group (2nd control) were incubated immediately, while the 3rd group (experiment) were exposed to % 0.1 Ethanole for 5 minutes and the 1st group (1st control) without any exposure to low temperature group were incubated . Results: The data analysis by one-way ANOWA show that the developmental rate of embryos exposed to low temperature (4°C) significantly decreased (P=0.001), retardation and arrest being produced. The mean of cleavage rate between groups were not significantly affected, but the mean percent of degenerated embryos between groups have significant differences (P=0.045). On the other hand the mean percent of morulla is significantly different between groups (P=0.005) similarly the mean percent of blastocyst and hatched blastocyst have significant differences between groups (P=0.014) (P=0.001) after 120 hr evaluation. Conclusion: Effect of %0.1 Ethyl-alchol on arrested two cell embryos can significantly increase the mean percent of morulla and development up to blastocyst and hatching blastocyst stage related to control group, without any significant effect on cleavage rate