Fig. 5

Injection of shh/vhh-1 RNA results in elevated and ectopic expression of nk2.2, axial and shh/vhh-1. Whole-mount embryos with rostral to the left. (A-F) Lateral views of 24h shh/vhh-1-injected embryos showing nk2.2 (A,D), axial (B,E) and shh/vhh-1 (C,F) expression. Eyes have been removed. (D-F) Examples of embryos affected more severely than those in A-C. (G,H) Dorsal views showing the gap in nk2.2 expression at the MDB of uninjected wild-type embryos (G) and the complementary expression of axial at the same location (H). The eyes are removed in H. (I) Dorsal view of expanded axial expression domain at the MDB in an shh/vhh-1-injected embryo. (J) Lateral view of axial expression in an control (left) and shh/vhh-1-injected 12 somite embryos. (K) Detection of b-galactosidase activity (blue) in embryos injected with b- galactosidase-encoding RNA. Some embryos were also examined for nk2.2 expression (eg. dark blue label in the forebrain of embryo at bottom left). (L) Higher magnification of the tail region of embryo seen bottom right in K. Blue cells are positive for b-galactosidase. Abbreviations: bl, blood; cf, cephalic flexure; h, hypochord; hy, hypothalamus; mb, midbrain; mdb, mid-diencephalic boundary; n, notochord; or, optic recess; sc, spinal cord; sk, skin; t, telencephalon; y, yolk; III, third ventricle. Scale bar=100 μm.