Nephric duct markers. (A-F) Stage 11 chick embryos stained by whole-mount in situ hybridization for Lim1 (A,B), cRet (C,D) and Pax2 (E,F). B,D,F are sections of A,C,E taken at the indicated axial levels. Note that Lim1 and cRet mark the nephric duct specifically, whereas Pax2 is expressed in both the nephric duct and nephrogenic cord. (G) Diagram of chick embryo indicating locations of components of the nephric system. (H-J) Summary of fate map of the intermediate mesoderm (IM) at stages 5 (H), 8 (I) and 10 (J). Anterior (future head) is upwards. IM migrates through the mid-portion of the primitive streak. Tissue that gastrulates earlier (blue) ends up in more anterior regions of the IM, including the nephric duct, whereas tissue that gastrulates later (yellow) ends up in more posterior, non-duct regions of the IM. c, nephrogenic cord; d, nephric duct; IM, intermediate mesoderm; lp, lateral plate; n, notochord; nt, neural tube; ps, primitive streak; psm, presomitic mesoderm; som, somite; t, tubule.