Other studies have confirmed that higher expression of Bax in particular, compared with Bcl-2, resulted in the cells sending a death command signal, but when Bcl-2 dominated, cell death was inhibited at the expense of cell survival (Korsmeyer, 1999; Suyama et al., 2001; Walsh et al., 2008). At the embryonic level, after incubation for 6 d, the expected expression levels of most of these genes were not the same and therefore may require further investigation.