Spatial expression patterns of AmSoxBb , AmSoxB1 and AmSoxE1 during early embryogenesis: A-F) AmSoxB1 ; (G-L) AmSoxBb ; (M-R) AmSoxE1 . (A, G, M) Early cleavage stage. (B, H, M) Blastula (prawnchip) stage. (C, I, O) Early donut stage, during gastrulation. (D, J, P) Transverse sections of C, I, O, respectively. (E, K, Q) Late donut stage, finishing gastrulation. (F, L, R) Transverse sections of E, K, Q respectively. Asterisks indicate the blastopore. 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). The speed of embryonic development is temperature dependent, so we have not attempted to give ages of the embryonic stages in this and later figures. Typical ages for the various stages are available in Figure 2 of Ball et al. .