Culture of Bovine Embryos in Polyester Mesh Sections: The Effect of Pore Size and Oxygen Tension on In Vitro Development

Contents The purpose of this study was to assess the feasibility of polyester mesh culture for the in vitro production of bovine embryos, as polyester mesh is an alternative way for tracking individual embryos throughout culture using time-lapse cinematography (TLC). Bovine embryos were isolated during in vitro culture using sections of three different polyethylene terephthalate (PET) mesh products. In vitro matured and fertilized bovine oocytes were cultured in the 217 x 217, 230 x 230 or 238 x 238-mu m openings of PET mesh sections or in simple micro-drops (control) for 7 days under either 20% or 5% O-2 tensions. No difference in embryo developmental rates was found between the culture groups in terms of cleavage, blastocyst formation and blastocyst expansion irrespective of O-2 tension. In contrast, under 20% O-2 tension, blastocysts that developed in PET mesh with 217 x 217-mu m opening had significantly higher numbers of total and trophectoderm (TE) cells than control embryos; however, the numbers and proportions of inner cell mass (ICM) cells did not differ. Under 5% O-2 tension, no difference was found among the culture groups in the numbers of total, ICM and TE cells in embryos. All three PET mesh products investigated in this study were proven to be effective to prevent embryo movement. The results demonstrate that bovine embryos can be cultured in PET mesh sections without negative side-effects and suggest that embryo distance determined by the mesh affects embryo quality at atmospheric oxygen tension. Polyethylene terephthalate mesh with 217 x 217-mu m openings was found to be the most suitable for further application in TLC.