Fig. 8. prd embryos have a delay in initiator cell behavior and CF formation. (A-D) Scanning electron microscopy of wild-type (A,C), prd (B,D), eve (E) and btd (F) embryos. Embryos are viewed on their lateral sides and are at early gastrula (A,B) and at mid-germband extension (C-F). (G-L) Embryos are stained with neurotactin (green), Eve (red) and Prd (blue). prd homozygotes were identified based on the absence of Prd staining. prd (H,J,L) or non-prd sibling (G,I,K) embryos of similar stages of gastrulation are shown. (G,H) Embryos are at the very onset of gastrulation. (I,J) Approximately 15 minutes into gastrulation; (K,L) early germband extension. Prd is expressed in the cell immediately anterior to the initiator cell, which corresponds to the middle cell of the first stripe of Eve. Eve and Prd therefore overlap in a single cell. Arrows mark either the initiator cell or the cell that would be an initiator cell in a wild-type embryo, as marked by localization relative to Eve expression. Note that the embryo in L, although at early germband extension, has barely begun a basal bulge of the CF and only on one side.