چكيده لاتين :
Background: Research studies on reproductive mechanism of laboratory animals are
essential for further advancement of assisted reproductive techniques (ART). One of these
studies includes the assessment of in-vitro development of pre-implantation embryos. The
objective was to compare the cleavage rates and morphology of in-vivo formed 2 to 8 cell
embryos 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 8ID
pregnant mareיs serum gonadotropin (PMSG, ip). Two superovulated animals were caged
with one male mouse for mating. Mated mice were killed by cervical dislocation at different
time intervals to collect a total of 200 (50/ each) 2, 4, 8, and blastocyst embryos from uterine
tubes and horns. Following morphological evaluation and cleavage rates, all embryos were
incubated in Whittinghamיs 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-evaluated
and compared with the original embryos.
Results: The best quality embryos collected from uterine tubes were at 2-cells stage, which
were reduced when compared with in-vivo developed 4-8 cells embryos. 880/0 and 520/0 of 2
and 8 cells embryos were respectively at grade A stage. 28 embryos out of 50 eight-cell
embryos were at grades C and 0 after incubation. Following in vitro culture, the development
of 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-vivo
blstocysts were increased (P>0.05).
Conclusion: In-vitro culture of the in-vivo formed embryos reduced their cleavage rates and
morphology, especially at more advanced stages. Therefore, it becomes necessary to improve
the in-vitro culture condition and to transfer the embryos at early stage to consequently
improve the implantation rates.
