Fig. 1. Schematic diagram of MEX-5 and PIE-1 proteins in a wild-type C. elegans hermaphrodite gonad, oocytes and early embryos. Germ nuclei (white circles) are in a syncitial cytoplasm of the gonad arm before being enclosed by membranes to form developing oocytes. The oocyte adjacent to the spermatheca undergoes maturation, and is then immediately ovulated and fertilized. Small black ovals: polar bodies. Nuclei are only shown in one-cell embryos. The levels of MEX-5 and PIE-1 proteins are indicated by shades of green and red, respectively. Yellow indicates the presence of both MEX-5 and PIE-1. The blue arrow indicates the proposed time for MBK-2 activation. Embryo images are oriented with the anterior pole to the left, with closed and open arrowheads pointing to the germline blastomere and its somatic sister, respectively. 1C Ana, first mitotic anaphase; 2C, two-cell; 4C, four-cell; 12C, 12-cell; DC, decondensation; MI, meiosis I; MII, meiosis II; ooc, developing oocytes; spm, spermatheca.