Effect of Oxygen Concentration in the Gas Atmosphere during In Vitro Insemination of Bovine Oocytes on the Subsequent Embryonic Development In Vitro

Abstract

In vitro matured bovine oocytes were co-incubated with sperm for 18 hr in a droplet of fertilization medium under a gas atmosphere of 5% CO₂ with 5 or 20% O₂. After removing the cumulus cells, they were fixed to examine their fertilization rate, or cultured for another 154 hr in a chemically defined medium under 5% O₂ to determine their development to the blastocyst stage. There was no difference between the 5 and 20% O₂ groups in the fertilization rate. However, the percentage of inseminated oocytes which developed to the blastocyst stage was higher when in vitro insemination was conducted under 5% O₂ compared with that under 20% O₂ (34.4 vs. 24.7%, P<0.05).