Fig. 2. Endodermal properties are altered in VAD embryos. Anterior dorsal views and transverse sections of normal and VAD whole-mount quail embryos hybridized with the markers indicated. (A-D'') Anterior expression of Bmp2 and Bmp7 in stage 4/5 normal and VAD embryos. The panels show only expression anterior to the node (asterisks). Lines (A,C,E) indicate the position of the transverse sections shown at hypoblast (hy) (A',C',E') and anterior definitive endoderm (en) (A'',C'',E'') levels. Note that at stage 4/5 Bmp2 and Bmp7 expression is detected at higher levels in hypoblast cells of VAD embryos (asterisks in B,B',D,D') than of normal embryos (A,A',C,C'). Furthermore, VAD embryos have an expanded expression domain of Bmp2 and to a lesser extent of Bmp7, in anterior definitive endoderm (arrowheads in B,B'',D,D''). (E-F'') Anterior endodermal expression of Hex in stage 5 normal and VAD embryos. Note the dramatic downregulation of Hex expression in anterior endoderm (arrow in F), in particular in definitive endoderm (F''), whereas expression in hypoblast is only partially reduced (F'). Scale bar in A: 100 µm in A-F; 40 µm in A'-F''.