Fig. 7.

Expression of LjHh and LjDlxA in embryos of the lamprey, Lethenteron japonicum. (A,B) Expression of LjHh in Tahara’s stage 19 embryo. Box in (B) is enlarged in (A). (C,D) Stage 21 embryo. Box in (C) is enlarged in (D). During these stages, LjHh is expressed in the prechordal plate that appears as the rostral continuation of the notochord. Compare with Fig. 5A,E,F. (E,F) LjDlxA expression in stage 24 embryo. (F) shows an oblique ventral view. (G) LjDlxA expression at stage 25. Note that this gene is upregulated during the pharyngular development in the ectomesenchyme in upper and lower lips. Whether the DlxA-positive ectomesenchyme in the upper lip consists only of the premandibular POC cells or contains mandibular arch ectomesenchyme remains unknown. Compare with Fig. 5H. fb, forebrain; nhp, nasohypophyseal plate; nt, notochord; ot, otocyst; pcp, prechordal plate; ph, pharynx; st, stomodaeum; ulp, upper lip.