The Effect of in Vitro Culture on Cleavage Rates and Morphology of the in Vivo- Developed Embryos in Mice

Background: research studies on reproductive mechanism of laboratory animals areessential for further advancement of assisted reproductive techniques (art). one of thesestudies includes the assessment of in-vitro development of pre-implantation embryos. theobjective was to compare the cleavage rates and morphology of in-vivo formed 2 to 8 cellembryos and blastocysts with in-vitro culture of the same embryos for 24 h.materials and methods: 6-8 weeks old female nmri mice were superovulated with 8idpregnant mare's serum gonadotropin (pmsg, ip). two superovulated animals were cagedwith one male mouse for mating. mated mice were killed by cervical dislocation at differenttime intervals to collect a total of 200 (50/ each) 2, 4, 8, and blastocyst embryos from uterinetubes and horns. following morphological evaluation and cleavage rates, all embryos wereincubated in whittingham's t6 media+5% bsa for 24 h. following incubation at 37°c in 5%c02, the cleavage rates as well as morphological feature of each embryo was re-evaluatedand compared with the original embryos.results: the best quality embryos collected from uterine tubes were at 2-cells stage, whichwere reduced when compared with in-vivo developed 4-8 cells embryos. 880/0 and 520/0 of 2and 8 cells embryos were respectively at grade a stage. 28 embryos out of 50 eight-cellembryos were at grades c and 0 after incubation. following in vitro culture, the developmentof 16%, 24°1ti, 240/0, and 40% of the 2, 4, 8 cells, and blastocysts were arrested, respectively.also, only 2 blastocysts (8%) reached the hatching stage which in comparison with in-vivoblstocysts were increased (p>0.05).conclusion: in-vitro culture of the in-vivo formed embryos reduced their cleavage rates andmorphology, especially at more advanced stages. therefore, it becomes necessary to improvethe in-vitro culture condition and to transfer the embryos at early stage to consequentlyimprove the implantation rates.