Fig. 5. Midbrain cells that cannot respond to Fgf signalling acquire forebrain character. Embryos were injected with 400 pg XFD-mRNA (A), grafts of these donor embryos were transplanted to a wild-type host embryos (B) and fixed at indicated stages prior to staining procedures (C). Arrows indicate transplanted cells. (D,F) Cell clones in the midbrain express the forebrain markers pax6.1 and efna4. Transplanted cells contain rhodamine dextran (E,G), but do not express the midbrain marker Engrailed, as visualized by -Engrailed antibody 4D9 staining (H-J). Control transplantations without XFD mRNA show co-localization of rhodamine dextran and -Engrailed staining (K-M). (J,M) Superimposed pictures of H,K and I,L. Transplanted cells do not express any of the hindbrain markers gbx1, fgf8 or krox20 (N,O). a, anterior; fb, forebrain; hb, hindbrain; p, posterior; r3, rhombomere 3.