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Novel Culture Systems for In Vitro Production and Transfer of Mammalian Embryos
In the first part of this study, a novel culture device the named oil-free micro tube culture (MTC) system for in vitro culture (IVC) of murine and porcine embryos was introduced. Parthenogenetic mouse and porcine embryos were placed into 0.2-mL thinwall flat cap PCR tubes and cultured to the blastocyst stage. Conventional drop culture was used as the control. Murine embryos in MTC had a higher blastocyst formation rate and larger population of cells in the blastocysts. This was due to higher numbers of trophectoderm (TE) cells rather than inner cell mass cells. On the other hand, the 'MTC' system in the pig showed similar (in 20 μl medium volume) or lower (in 10 μl medium volume) blastocyst formation rate when compared with drop culture system. In the second part of this study, dexamethasone (DEX) and leukemia inhibitory factor (LIF), which suppress PGF2α, were directly supplemented into ET media, and transfer of the embryos to surrogate was followed. In the cattle industry, embryo transfer technology has been used to produce the most valuable cows or bulls. Numerous factors such as heat stress, mastitis, manipulating female reproductive tract may contribute to early embryonic loss through premature increases of uterine luminal concentrations of PGF2α in cows. Furthermore, addition of PGF2α to culture medium has been shown to inhibit the development and hatching of mammalian embryos. When DEX and LIF were supplemented, the pregnancy rate (6 month post-ET) was increased from 56.0% to 68.3%. In IVC experiment, DEX and LIF supplementation supported hatching of bovine embryos in the presence of PGF2α in the medium (from 16.9% to 40.6%). Additional ET experiments using alternative drugs are currently under investigation. The present work was supported by the Technology Development Program for Agriculture and Forestry, Ministry for Food, Agriculture, Forestry and Fisheries (MIFAFF; 109020-3).
