Figure 2.

A flow-chart illustrating the embryo culture system. Fertilization checks were performed on day 1 (D1) between 16 and 18 h after insemination by conventional IVF or ICSI. Normal fertilized (2PN) oocytes were allocated to either a K-system (G185) or Embryoscope incubator based on space availability. Pronuclear stage embryos were cultured in G¹⁺ medium until day 3 (D3). In cases where only one or two embryos are available, ET was performed on day 2. Embryos cultured in the conventional style box incubator and K-system were graded morphologically under a stereomicroscope at, approximately, post-insemination/injection on day 2 (44 ± 1 h), D3 (68 ± 1 h), D5 (116 ± 2 h) and D6 (140 ± 1 h). In the Embryoscope, morphological grading of embryos was performed at the same time-points by examining the time-lapse images. On D3, embryos were selected for replacement, for cryopreservation or for extended culture to the blastocyst stage: the latter were transferred to new culture dishes or Embryoscope slides containing G²⁺ medium for further culture to day 6. On day 5, the highest quality blastocysts were selected for either single embryo transfer (SET) or double embryo transfer (DET). Cryopreservation was by slow freezing (SF) for cleavage on D3 and vitrification (VIT) for blastocyst stage embryos. TLI, time lapse incubator **Embryoscope incubator timelapse assessment, *stereomicroscope assessment.