Fig. 4.

The prospective IM region of the stage 8 primitive streak is not competent to form nephric duct. (A-H) Transplants of quail stage 4 (A-D) or stage 8 (E-H) mid-primitive streak were labeled with DiI and grafted into the equivalent area of the primitive streak of stage 4 chick embryos. As indicated by the DiI localization (B,F), graft cells migrated into the duct formation region (arrows indicate somite 10). Embryos were sectioned and stained for Lim1 (C,G, green), the quail marker QCPN (C,G, red) and DAPI (D,H). Stage 8 grafts did not differentiate into Lim1-expressing duct tissue (E-H), whereas stage 4 control grafts exhibited robust duct differentiation (A-D). c, nephrogenic cord; d, nephric duct; lp, lateral plate; nt, neural tube; psm, presomitic mesoderm.