Cysteine, glutathione, and percoll treatments improve porcine oocyte maturation and fertilization in vitro

Several factors have been examined to improve in vitro fertilization and development of porcine oocytes. Cysteine is known to be beneficial for oocyte maturation and male pronuclear formation in pigs and glutathione is known to help prevent membrane disruption of sperm in other species, including human, it has also been reported that the presence of cumulus cells influences the outcome of in vitro fertilization in cattle. The objectives of the present study were to investigate the effects of several factors involved in porcine in vitro maturation (IVM) and fertilization (IVF) procedures on oocyte embryogenic competence. The following factors were examined: the effects of different concentrations (0, 0.285, 0.57, 1.14, 2.28 muM) and exposure duration (22 and 44 hr) of cysteine during IVM, glutathione inclusion and of cumulus presence during IVF, and the use of gradient Percoll (45%/90%) during sperm preparation. The presence of cysteine in maturation medium improved blastocyst development significantly regardless of the duration of exposure when compared to the control (11-16% vs. 4%, P < 0.01). However, no dose-responsive effect was observed at the concentrations tested. The use of gradient Percoll during sperm preparation significantly improved cleavage (85% vs. 57%, P < 0.01) and blastocyst development (24% vs. 6%, P < 0.01) over conventional sperm preparation. Significant improvement was also achieved by the addition of glutathione to Percoll gradient (30% vs. 20%, P < 0.05). In conclusion, cysteine and glutathione as well as Percoll and cumulus were beneficial to embryogenic competence of porcine oocytes in this study. (C) 2001 Wiley-Liss, Inc.