The Effect of Several ?-Tocopherol Concentrations on Swine Oocyte Maturation and Embryo Culture

Abstract

Free radicals play significant roles in the physiological processes happening in the ovary such as steroidogenesis, folliculogenesis, corpus luteum progesterone release and degeneration, and follicle rupture during ovulation. As defence, living systems employ antioxidants that they either produce or take up from the environment. Among these ?-topherol has been shown to improve swine oocyte maturation and the development of bovine and swine embryos. The goal of this study was to establish the influence of several ?-tocopherol concentrations on swine oocyte maturation, viability, the function of cumulus cells and in vitro embryo development in order to improve culture media. Pig oocytes were cultured for 45 hours at 38°C in 5% CO2 atmosphere; in M199 containing several ?-tocopherol (5, 10, 20, 40 and 80 µM) concentrations and cumulus expansion was assessed. Then they were fertilized in TALP medium using spermatozoa capacitated by centrifugation and incubated for 16-18 hours Afterwards the presumed zygotes were cultured in NCSU-23 droplets supplemented with ?-tocopherol (5, 10, 20, 40 and 80 µM) and covered with mineral oil for 92 hours at 38°C in 5% CO2 atmosphere. At the end of this period the number of embryos that had developed to the 2 cells, 4-8 cells and morula stages was counted and compared to the control, and the differences analyzed using ANOVA and interpreted using the Student test. The addition of 20 µM ?-tocopherol to the maturation medium lead to a significant (p<0.05) increase in the number of matured oocytes. Culturing swine embryos in media supplemented with 5 ?M, 10 ?M and 40 ?M ?-tocopherol also had a beneficial effect in their development to the morula stage resulting in higher number of viable swine embryos