Wild-type and blastomere transformed embryos at the 8-cell stage of embryogenesis. Top: A wild-type embryo at the 8-cell stage showing the founder blastomeres (MS, E, C, P3) and four AB descendents. Middle: Treatment of the parental hermaphrodite with mex-1 RNAi results in conversion of the four AB descendents into MS-like founder blastomeres that execute an MS-like fate [16]. Bottom: Treatment the parental hermaphrodite with mex-1, lit-1, pal-1 triple RNAi results in an embryo comprised mostly of MS-like blastomeres. The fate of the C founder cannot be specified in the absence of PAL-1 [14].