Fig. 4.

Co-expression of an FGF ligand, NvFGF1A, and a receptor, FGFRa at the aboral pole during development. NvFGF1A is first expressed during gastrulation where transcripts accumulate at the aboral pole in a broad domain (a). This domain of NvFGF1A expression becomes restricted to fewer cells as development proceeds (b–d). During planula and polyp development, expression can only be found in the ectodermal cells that give rise to the apical tuft (c–d). e–h NvFGFRa is expressed in a pattern nearly identical to that of NvFGF1A, except the initial expression domain of NvFGF1A is broader during gastrulation and early planula development (e, f). All embryo views are lateral, with the asterisk denoting the blastopore and future oral side