Fig. 4

Fluorescent whole mount in situ hybridization analysis of a representative cadherin gene (Sp-pcdh9). Each image shows a z-projection of confocal slices (15–73 slices/stack). Red- Sp-pcdh9 mRNA. Blue- Hoechst staining (nuclei). At the late mesenchyme blastula (MB) stage, strong signal is seen in the vegetal plate (large arrowhead) but is absent from migrating primary mesenchyme cells (small arrowhead). At the early gastrula (EG) stage, signal is elevated at the margin of the blastopore (large arrowheads) but is absent from migrating secondary mesenchyme cells (small arrowhead). At the early prism (EP) stage, expression is highest at what appears to be the foregut/mid-gut boundary and in the circumblastoporal region (small arrowheads), as well as in the apical plate (large arrowhead). At the pluteus (PL) stage, expression is elevated in the ciliary band, especially overlying the postoral arms (large arrowhead), and in the gut (arrowhead). Asterisks indicate the archenteron. MB- mesenchyme blastula (24 hpf). EG- early gastrula (28 hpf). EP- early prism (44 hpf). PL- pluteus (72 hpf). Early gastrula stage embryos are shown in lateral (lat) and vegetal pole (vp) views. Scale bar = 50 μm