Fig. 1.

The ANE territory is segregated into two concentric domains. (A) Schematic model showing the progressive positioning of expression of the cardinal ANE regulators foxq2 and six3 around the anterior pole of early S. purpuratus embryos from the 60-cell to the mesenchyme blastula stage (data from Li et al., 2014; Wei et al., 2009; Yaguchi et al., 2008). (Ba-c) foxq2 expression is nested within the fzl5/8 expression domain and is surrounded by six3 expression. Two-color in situ hybridization for foxq2 (green) and fzl5/8 (red) transcript expression at the mesenchyme blastula stage; overlap appears in yellow.