Localization of c-met expression by whole-mount in situ hybridization. (A) Lateral view of stage-16 embryo. c-met expression is detected in the ventral region (with the exception of the region behind the prospective cement gland) in a salt-and-pepper fashion and in the ectoderm in a mosaic fashion. (B and C) Lateral and ventral view, respectively, of stage-17 embryo. c-met staining increases as development proceeds. (D) Lateral view of stage-23 embryo. c-met expression is maintained in the ectoderm but decreased in the dorsal mesoderm. (E) Lateral view of stage-36 embryo. c-met is detected in the liver, midbrain, otic vesicle, pronephric tubules, pronephric duct, heart, and posterior mesoderm near the anus. ccv indicates common cardinal vein; h, heart; lv, liver; mb, midbrain; ov, otic vesicle; pn, pronephric tubules; and pnd, pronephric duct. (F) Transverse section of stage-17 embryo. c-met staining is present in the mesoderm layer beneath the ectoderm (black arrowheads).