Effects of Delipidation and Oxygen Concentration on In Vitro Development of Porcine Embryos

摘要

The effects of delipidation and the oxygen (O_2) concentration in the atmosphere during culture on in vitro development and H_2O_2 content were investigated in porcine in vivo fertilized embryos and embryos after in vitro maturation and in vitro fertilization (IVM/IVF embryos). There was no significant difference in the developmental rates to the blastocyst stage between the intact and delipidated IVM/IVF embryos. However, the mean number of cells in blastocysts derived from delipidated IVM/IVF embryos (19.8 ± 0.8 cells) was significantly smaller than that from intact embryos (24.2 ± 1.2 cells). Although there were no significant differences in the developmental rates to the blastocyst stage of intact and delipidated IVM/IVF embryos between the cultures under 5% O_2 and 20% O_2, the developmental rate of intact IVM/IVF embryos cultured under 5% O_2 (27.1%) was significantly higher than that of the delipidated embryos cultured under 20% O_2 (19.3%). On the other hand, there was no difference in the developmental rate to the blastocyst stage between in vivo fertilized embryos cultured under 5% O_2 and 20% O_2. Hydrogen peroxide (H_2O_2), one of the reactive oxygen species (ROS), is thought to cause damage to embryos. The H_2O_2 content per embryoderived from oocytes cultured under 5% O_2 (in vivo fertilized, 58.0 ± 2.5 pixels; IVM/IVF, 79.6 ± 3.2 pixels) was significantly lower than that (in vivo fertilized, 100.2 ± 3.8 pixels; IVM/IVF, 103.9 + 3.2 pixels) under 20% O_2. Furthermore, the level of H_2O_2 in delipidated IVM/IVF embryos (94.7 ± 3.9 pixels) was significantly lower than that in intact embryos (103.9 ± 3.2 pixels) cultured under 20% O_2. The present results indicate that the delipidation of porcine IVM/IVF embryos and reductionof the O_2 concentration decreased the H_2O_2 level rather than the in vitro developmental rate to the blastocyst stage.