AH.lacZ embryonic brain expression reflects dCORL and not Toy. Stage 16 embryos. Left half dorsal views and right half lateral views. A) Eve (brown) and dCORL RNA (purple). Eve is present along the aorta in two anterior-posterior rows each composed of 2 pericardial cells per segment. Where the aorta squeezes between the brain lobes Eve cells are irregularly arranged (red arrowhead). dCORL medial brain expression appears associated with Eve at this location. B) dCORL RNA is located in groups of cells laterally in the brain (protoerebrum – purple arrowheads) and in a medial group of cells. dCORL is also found in pairs of cells at several locations along the pharynx (example shown with white arrowhead). C, C’) Top half of slices of the brain revealing Eve (red), Fas2 (blue) and AH.lacZ (green) or just Eve and Fas2. Strong protocerebral AH.lacZ expression approximating dCORL RNA is visible (purple arrowheads; lacZ expression overflows the nuclei and is visible in cell bodies). The accurate but incomplete reflection of dCORL expression of AH.lacZ is shown by the lack of expression near the irregularly spaced Eve cells (red arrowhead) and lack of expression near the pharynx (white arrowhead). D) Bottom half of slices from the same embryo displaying ventral expression in the trito-, deuto and protocerebrum (from ventral to dorsal orange, aqua and purple arrowheads, respectively). E) Top half of slices of the brain revealing Toy (red), Fas2 (blue) and AH.lacZ (green) or just Toy and Fas2. Strong protocerebral AH.lacZ expression (purple arrowheads) appears to overlay Toy expression dorsally as well as to the anterior and posterior. F) Bottom half of slices from the same embryo displaying AH.lacZ ventral expression in the protocerebrum (purple arrowheads) anterior and posterior to Toy as well as in the trito- and deutocerebrum (orange and aqua arrowheads). G) Eve (brown) and dCORL (purple). Eve is adjacent to dCORL where the aorta squeezes between the brain lobes (red arrowhead). Close-up view of the ventral brain region of the same embryo revealing dCORL expression in the protocerebrum (purple arrowhead). dCORL expression in the trito- and deutocerebrum (orange and aqua arrowheads) is associated with Eve. H) Complete stack, medial half of slices and apical slices from the quarter of the brain closest to the viewer revealing Eve (red), Fas2 (blue) and AH.lacZ (green). AH.lacZ trito- deuto- and protocerebral expression (orange, aqua and purple arrowheads) is visible with the former two associated with Eve. I,J) Medial half of slices and apical slices from the quarter of the brain closest to the viewer revealing Toy (red), Fas2 (blue) and AH.lacZ (green) or just Toy and Fas2. Both views show that AH.lacZ protocerebral expression (purple, arrowheads) is present anterior and posterior to Toy. Taken together (E,F,I,J) show the envelopment of protocerebral Toy expression on its dorsal, anterior and posterior sides by AH.lacZ.