Comparison of AmItgα1, AmItgβ1 and AmItgβ2 mRNA distribution patterns during gastrulation in Acropora. At the prawn chip stage, the AmItgα1 and AmItgβ1 mRNAs are clearly restricted to one side of the flattened cell bilayer (A, A', D). During gastrulation, these mRNAs are tightly restricted to the area of the blastopore (asterisks) lip (B, B', C, C', E, F), and throughout development remain endodermal. The distribution of AmItgβ2 mRNA (G, H, I) is broadly similar to that of AmItgα1, but is less tightly restricted, as indicated by weak general staining. Arrow heads in A, B, and C indicate the plane of the sections shown as A', B' and C'.