Fig. 1.

Summary of 53 maternal-effect gene (MEG) products active during oocyte growth and meiosis resumption (green box), fertilization (orange box) and early preimplantation development (blue box). The purple-shaded area represents the moment when the embryonic genome activation occurs. MEGs are grouped according to their specific function and located depending on the site where they exert their main activity. For each MEG, the lethality stage observed in experimental models is indicated with a red arrow. All the experiments were performed in the mouse, except for Spind1, whose lethality was detected in the porcine model. The absence of the red arrow indicates that the lethality stage is not yet available. GV, germinal vesicle; MII, metaphase II; FERT, fertilization; PN, pronuclei; ZYG, zygote; MOR, morula; BL, blastocyst; POST-IMP, post-implantation; COC, cumulus-oocyte complex