Abstract: The aim of this investigation was to study the efect of brilliant cresyl blue(BCB)staining on IVM-IVF in cow．For this purpose，oocytes were stained by BCB and selected by IVF examination before mature culture．COCs without BCB staining was considered as control group，and COCs stained with BCB in 26 μmol／L for 90 min as treatment group before mature culture．Treated oocytes were divided into BCB一(eolourless cytoplasm)and BCB+ (coloured cytoplasm)．After
1VM，oocytes were fertilized in vitro(ⅣF)．The cleavage rate of eggs at 48 h and the proportion of blastocysts at 8 d after 1VF were compared．The results showed that：(1)The BCB+ oocytes had a signiiicanfly higher proportion of mature rate (80．83％)than control group and BCB—oocytes(60．20％ and 51．92％)(P <0．05)；(2)The BCB+ooeytes had a signiticanfly higher proportion of blastocysts(32．99％)than control group and BCB-oocytes(17．64％ and 3．57％)(P

Key words: Cow, oocytes, IVF, brilliant cresyl blue