Spatial expression pattern of AmSoxBa during development. (A) There is no expression in the early prawnchip stage, (B) Initiation of gastrulation in the late prawnchip stage. AmSoxB2 transcripts appear in the presumptive ectoderm with some cell specific staining. (C) At the donut stage the general ectodermal expression and some cell specific staining persist. (D) Transverse section of C. Expression is restricted to the presumptive ectoderm. (E) Pear stage (F) Longitudinal section of E shows ectodermal expression. (G) Late pear or early planula stage. (H) Longitudinal section of G. (I) Planula stage (96 h). Cell specific expression is restricted to the aboral half of the ectoderm. (J) Section image of I. (K) Post settlement polyp. (L) Transverse section of K. Expression is now missing from the aboral ectoderm. Asterisks indicate the position of the blastopore. (E-J) Oral pore is oriented to the left and aboral side to the right. Paired arrows on a panel of the figure indicate that the next panel is a section in the plane of the arrows (e.g. D is a transverse section of the embryo shown in C).