Localization of HGF expression by whole-mount in situ hybridization. (A) Lateral view of stage-14 embryo. HGF is detected in the head mesenchyme and neuroblasts. (B and C) Lateral and ventral view, respectively, of stage-20 embryo. HGF is expressed in the branchial arches and ventral region. Ventral expression of HGF forms a V-shaped pattern. (D) Lateral view of stage-24 embryo. Ventral expression of HGF is decreased. Staining is evident in the branchial arches and dorsolateral plate (DLP) mesoderm (black arrowheads). (E) Lateral view of stage-36 embryo. HGF is detected in the branchial arches, embryonic vasculature (common cardinal vein, posterior cardinal vein, and pronephric sinus), and heart. (F) Transverse section of stage-20 embryo. HGF staining is present in the mesoderm layer beneath the ectoderm (black arrowheads). br indicates branchial arches; ccv, common cardinal vein; h, heart; pcv, posterior cardinal vein; and ps, pronephric sinus.