Developmental expression of Fezf in amphioxus and Drosophila. (A-D) Expression of Branchiostoma lanceolatum Fezf (purple) during embryogenesis. (A) Dorsal view of an early neurula showing the highly restricted Fezf expression (purple) in the anterior neural plate. Expression is observed only in the anterior-most six to seven rows of cells in the neural plate. (B) Side view of the same stage shown in (A). (C) Dorsal view of a mid-neurula stage, showing similarly strongly restricted anterior neural expression. (D) Lateral view of a premouth larva. Anterior is to the left and dorsal is up. (E-J): Expression of Drosophila Fezf (purple) during embryogenesis, as previously reported , in embryos at stages 4 (syncitial blastoderm), 5 (cellular blastoderm), 8, 10, 11-12 and 14, respectively, as described previously . Anterior is to the left. (E, F, H-J) dorsal views; (G) dorsolateral view. Arrowhead in (G) indicates the dorsal split of the initially continuous stripe. br brain hemispheres.