Fig. 5. The regionalization of the primitive streak and the specification of the
mesoderm are partially maintained in murine
Fgf8
b-neo/
b-neo
embryos. (A-L) In situ hybridization analysis of markers (indicated
to the left) characteristic for Fgf8 signaling and mesoderm in wild-type and
Fgf8
b-neo/
b-neo
embryos at E7.5. (A-D,I,J) Adjacent sagittal sections of wild-type (A,C,I) and
Fgf8
b-neo/
b-neo
(B,D,J) embryos. Inset in B shows whole-mount analysis of Fgf8
expression. Notice that axial mesoderm marked by T and Foxa2
expression is absent anterior to the streak of
Fgf8
b-neo/
b-neo
embryos, indicating a lack of mesoderm migration. (E,F) Asterisk indicates
Evx1 expression at the proximal end of the primitive streak.