caption: Effect of β-ME on (35S)cystine uptake of bovine embryos. Ten 1-cell, 8-cell, morula, and blastocyst stage embryos were incubated for 30 min in cystine, cysteine-free TCM-199 plus (35S)cystine with or without 100 μM β-ME. After incubation with or without β-ME, the radioactivity of incorporated (35S)cystine was measured with a scintillation counter. Data show means ± SEM. n, The number of replications; a vs. b, P < 0.05; a vs. c, P < 0.0001; b vs. c, P < 0.01