Fig. 3.

NvFGF8A is expressed during gastrulation and during apical tuft formation. In situ hybridization of an antisense RNA probe towards NvFGF8A shows that NvFGF8A is not expressed during cleavage (a) or blastula (b) stages. Transcripts first appear at the onset of gastrulation, with staining visible in the blastopore (c–e). Expression remains restricted orally, to the developing pharynx in pharyngeal ectoderm (f–h). During planula and polyp development, transcripts are also detectable at the base of the apical tuft, in the ectoderm (g–j). During tentacle bud formation, expression is also detected in a few cells at the tips of the growing mesenteries and in the accompanied body wall endoderm (h–j). All embryo views are lateral, with the asterisk denoting the blastopore and future oral side, except (a) and (b), which are cleavage and blastula stage embryos, and (e), which is an oral view