Figure 1

Schematic representation of experimental design. During an OPU session, all COCs retrieved from a single cow were subjected to in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC-I) for up to 24 h. After 24 h of IVC, the presumed OPU zygotes were cultured either (1) alone (2~8) or (2) cocultured (2~8) with agar chip-embedded slaughterhouse presumed zygotes (8~2). Moreover, a group of ten slaughterhouse-derived presumed zygotes were cultured (sIVP) to supply presumed zygotes for coculturing with OPU presumed zygotes or for the evaluation of embryonic development.