Fig. 1. Expression of cyp26 at gastrula to early somitogenesis stages. Views of whole embryos (orientation indicated to the left of each row) at the stages indicated on top of each column. cyp26 was stained by in situ hybridization (purple), while ntl (red) was used to mark the blastoderm margin (A, A', open arrowhead) and developing notochord (C,F, asterisk). cyp26 is expressed in the presumptive anterior neural ectoderm (A,A' filled arrowhead) and at the blastoderm margin (A,A' open arrowhead) throughout gastrulation (B-D). Subsequently, expression in the anterior neural ectoderm decreases rapidly (E'', F'' filled arrowhead), while expression continues in the tail bud.