Effects of oxygen concentration in IVM/IVF on marmoset monkey oocyte maturation and embryo development

ABSTRACT

The effect of oxygen (O2) concentration on in vitro development of the oocytes from antral follicles of naturally cycling common marmosets (Callithrix jacchus) has been investigated. Different O2 concentrations during in vitro maturation (20 or 8%) and during in vitro fertilization (20 or 5%) have been applied in three combinations 8-5, 20-20, 20-5 (maturation and fertilization, respectively). Additionally, 8-20 conditions were tested in a pre-study, but since no fertilization occurred, this test group was excluded from further experiments. Oocyte maturation rate was significantly higher after IVM in 20% than in 8% O2 (MI 91% in 20-20 vs. 78% in 8-5; MII 69 vs. 45% in 20-5 and 50% in 8-5, P < 0.05 for all). The lowest rate of embryo development occurred after maturation under 8% O2 (59% in 8-5 vs. 95% in 20-20 and 83% in 20-5, P < 0.05 for all), strongly suggesting this low tension may produce hypoxic conditions during maturation, which damages the oocytes. In conclusion, 20% O2 was shown to be significantly superior to 8% O2 for marmoset oocyte maturation, and 5% O2 was to be preferred over 20% for IVF, based on a trend for better embryo morphology and rates of progression.