Figure 3.

The effect of duration and periods of changes in O₂ tension growth rates in vitro. Hybrid strain zygotes were cultured in groups of 10 in 10 μL of sIVF cleavage medium in 5% or 20% O₂ for 48 h. Each treatment was divided into two subgroups and cultured in sIVF blastocyst medium for a further 48 h in 5% or 20% O₂. The rate of blastocyst formation (A) 96 h post-hCG and (B) 116 h post-hCG, and the (C) the rate of blastocyst hatching, and (D) the total numbers of cells, (E) fragmented nuclei in the resultant 116 h post-hCG blastocyst was analysed. The results are representative of at least 100 embryos for each treatment from three independent replicates. *P < 0.001, compared to the corresponding treatment group of embryo that was cultured in different O₂ tension. **p < 0.001, compared to the embryos that were cultured in 5% O₂ for 48 or 96 h.