Fig. 5. Partial rescue of the head and forebrain defects in the
Dkk1-/- embryo with reduced Wnt3 gene dose.
(A) Comparison of the morphology of the
Dkk1+/+;Wnt3+/+,
Dkk1-/-;Wnt3+/- and
Dkk1-/-;Wnt3+/+ embryos
showing the almost complete to partial restoration of head structures in the
Dkk1-/-;Wnt3+/- embryo at E9.5 and E10.5.
(B) Marker analysis of wild-type
(Dkk1+/+;Wnt3+/+), `rescued'
(Dkk1-/-;Wnt3+/-) and Dkk-null
(Dkk1-/-;Wnt3+/+) embryos (E8.5: TopGal,
Six3 and Fgf8; E9.5: En1 and Dlx5). The
presence of TOPGal-free and Six3-expressing domains (arrows) show the
restoration of forebrain tissue in the `rescued' embryos. Expression of
Fgf8 is present in the commissural plate (arrow) of the rescued
embryo but is weaker than the wild type, whereas the isthmus is restored to a
normal position (asterisk) that is shifted rostrally in the
Dkk1-/-;Wnt3+/+ embryo. En1 is
restored to nearly wild-type pattern in the midbrain of the rescued embryo
(asterisk). Dlx5 expression (arrows) reveals the improved development
of the branchial arch in the rescued embryo.