Expression of Ct-eve1. Stages are marked in the lower left of each panel and anterior is to the left for all panels. Except for B, D, J (lateral views with ventral down) and K (dorsal view), all panels are ventral views. An asterisk marks the blastopore in A and B and the mouth in all other panels. (A,B) Ventral (A) and lateral (B) views of the same animal. At the end of gastrulation, Ct-eve1 is expressed in mesodermal precursor cells (arrows in A) and the presumptive brain (br). (C,D) Expression in the presumptive brain (br), mesodermal bands (large arrows), endoderm (end) and ectodermal cells positioned immediately anterior to the telotroch (small arrows). Panel C is a composite of multiple focal planes. (E) Expression is in the brain (br), presumptive foregut (fg), mesodermal bands (large arrows) and hindgut (arrowhead). (F-H) Expression is throughout the mid-body mesoderm as it expands circumferentially (bracket in F, arrows in G) and there is continued expression in the brain (br), foregut (fg) and hindgut (arrowhead). F-H are different focal planes of the same animal. (I) Expression during Stage 6 includes the brain (br), foregut (fg), mid-body mesoderm and mesodermal precursor cells (arrows). (J,K) By Stage 8, the most prominent expression is in the posterior mid-body (bracket), with weaker expression in the brain, foregut and hindgut. (L) In late larval stages, expression is largely restricted to the PGZ (arrow). br: brain; end: endoderm; fg: foregut; St 3b: Stage 3 blastopore; tt: telotroch.