Fig. 10

Whole-mount in situ hybridization of wild-type (A) and vgo (B) embryos with fkd-7. At 33 hpf fkd-7 is expressed not only in the medial pharyngeal endoderm but also in the developing pouches (A, arrows). The expression pattern of fkd-7 in vgo within the medial endoderm (B) indicates that the reduction of the pouches is not caused by a general reduction of the endoderm, even though the expression domain is shorter than in wild-type siblings. (C–F) Ventral views of expression patterns of nkx2.3 and nkx2.5 in 30-hpf and 15-somite wild-type (C, E) and vgo mutant larvae (D, F) (anterior to the left). nkx2.3 is expressed in the endodermal pouches in a pattern complementary to that of dlx-2 (Fig. 8C). At this stage the posterior pouches are not separated from each other and appear as a thicker patch of staining (C, arrow). In vgo expression in the endodermal pouches is very much reduced, although it is present in the most anterior pouches (D). At 15 somites nkx2.5 is expressed in precardiac mesoderm as well as in prospective anterior endoderm (E). In vgo the expression in the precardiac mesoderm is normal, whereas the endodermal expression is absent (F). The reduction of nkx2.5 in the endoderm is the earliest defect observed in vgo.