Addition of Cysteamine to a Serum-free Maturation Medium Enhances In Vitro Development of IVM-IVF Bovine Oocytes

Abstract

Bovine cumulus-enclosed oocytes were matured in vitro (IVM) in PVA-HEPES-TCM199 supplemented with 0, 0.5, 5, 50 or 500 μM cysteamine for 24 h and fertilized in vitro (IVF). After removal of cumulus cells, IVM-IVF oocytes were cultured in vitro for 8 days. Cysteamine had no effect on oocyte maturation or fertilization rates. In contrast, 5 μM cysteamine in the maturation medium enhanced subsequent in-vitro development of IVM-IVF oocytes to the blastocyst stage. Glutathione (GSH) content of oocytes cultured in medium with 0 or 0.5 μM cysteamine was significantly lower than that of oocytes before culture. When oocytes were cultured in medium with 5, 50 or 500 μM cysteamine, GSH content of oocytes remained constant (5 μM) or was significantly increased (50 or 500 μM) compared with that of oocytes before culture. These results indicate that the addition of cysteamine to a serum-free maturation medium enhances the efficiency of in vitro production of bovine embryos by maintaining GSH content of IVM oocytes.