Brilliant Cresyl Blue Negative Oocytes Show a Reduced Competence for Embryo Development after In Vitro Fertilisation with Sperm Exposed to Oxidative Stress

Abstract

The extent of oxidative damage transferred by the damaged sperm to the progeny is likely to be limited by the oocyte’s repair and antioxidative capacity. We aimed to assess the association between Brilliant Cresyl Blue (BCB) staining in oocytes and their competence for embryo development after in vitro fertilisation (IVF) with damaged sperm. For this purpose, bovine sperm were incubated without (non-oxidised sperm, NOX S) or with 100 µM H2O2 (oxidised sperm, OX S) and were used to fertilise in-vitro-matured bovine oocytes (BCB-pos./BCB-neg.). Unstained oocytes served as controls (US). Development was assessed at 30, 46, 60 h and on Days (D) 7 and 8 after IVF. Total cell number and apoptotic index were analysed in D7 blastocysts. BCB-neg. oocytes showed lower cleavage rates and blastocyst rates than unstained oocytes after IVF with NOX S (p < 0.05). They showed the highest reduction in D7 blastocyst rate upon fertilisation with OX S and showed a delayed embryo development at 46 and 60 h after IVF compared to embryos produced with NOX S (p < 0.05). Total cell number in blastocysts produced with BCB-neg. oocytes was lower (p < 0.05) in the embryos produced with OX S than in embryos after IVF with NOX S. In conclusion, BCB-neg. oocytes have a lower competence to support embryo development after in vitro fertilisation with oxidised sperm.