Fig4K. Copyright: Reprinted with permission from Cell Press from [doi:10.1016/S1534-5807(02)00321-0] Dev Cell 3(5): 745-56, Perea-Gomez A; Vella FD; Shawlot W; Oulad-Abdelghani M; Chazaud C; Meno C; Pfister V; Chen L; Robertson E; Hamada H; Behringer RR; Ang SL, Nodal antagonists in the anterior visceral endoderm prevent the formation of multiple primitive streaks. Copyright 2002 [PMID:12431380]