Fig. 7

Ectopic Expression of axial after Injection of shh RNA into Fertilized Zebrafish Eggs
(A-C) Whole-mount uninjected and injected embryos hybridized with axial probe after 28 hr of development are shown. (A) axial expression in three wild-type (wt) embryos (left) and three embryos injected (inj) with shh mRNA at the 1- to 4-cell stage (right). Notice the different degree of ectopic axial expression in the head of different embryos, in particular in the ectopic posterior stripe (arrow). (B) axial expression in the head of a control embryo at 28 hr of development. The arrow shows the narrow axial stripe in the diencephalon. The dotted line shows the eye. (C) axial expression in the head of an embryo injected with shh synthetic RNA. Arrowheads mark the broadened axial expression in the diencephalon. The arrow shows the ectopic posterior stripe of axial expression in the midbrain/hindbrain region. The dotted line marks the rudimentary eye.
(D) Horizontal section through the head of a 28 hr wild-type embryo; note the narrow stripe of axial expression through the diencephalon (arrowhead).
(E) Horizontal section through the head of a 28 hr injected embryo; note the broadened stripe of axial expression in the diencephalon (arrowhead) and the ectopic expression in the midbrain (arrow).
(F) Transverse section through the midbrain of a 28 hr injected embryo showing asymmetric distribution of axial-expressing cells.
Abbreviations: d, diencephalon; f, forebrain; h, hindbrain; and m, midbrain.