Fig. 1. Positions and fates of eight-cell stage C. elegans embryonic blastomeres in wild-type and mutant backgrounds. A diagram showing the relative positions of the wild-type AB granddaughters (AB⁴) and the P₁ granddaughters MS, E, C and P₃ is given at the top. Depletion of mex-1 and pie-1 individually and together results in the fate transformations shown at the bottom of the figure (Mello et al., 1992). The table summarizing the major embryonic cell types made by descendants of AB, MS, D and C was adapted from lineage data (Sulston et al., 1983). In embryo diagrams, anterior is towards the left, and dorsal is upwards.