Fig. 2. Expression of Bithorax-Complex genes in the dorsal vessel. For each BX-C gene product, single-channel views of an embryo stained with an antibody to the BX-C product (A,E,I, top row) and the same embryo stained with an antibody to MEF2 (B,F,J, second row) are shown. These images are merged in the third row (C,G,K). The top three rows of micrographs represent combination of several individual z-series images. This is necessary to show the arrangement of the entire dorsal vessel. To confirm co-expression in the mesoderm, the lower row shows the combined images for only one or two optical sections (differing by 2 µm). (A) UBX accumulation. (B) MEF2 accumulation in the same embryo. (C) Merged image of A and B (UBX in green, MEF2 in red). (D) Merged image at limited optical sections to show co-expression in the mesoderm. UBX was detected broadly albeit at low levels in the dorsal vessel. (E) ABDA accumulation. (F) MEF2 accumulation in the same embryo. (G) Merged image of E and F (ABDA in green, MEF2 in red). (H) Merged image at limited optical sections to show co-expression in the mesoderm. ABDA was detected in cardial (yellow) and pericardial (green) cells of the heart region only. (I) ABDB accumulation. (J) MEF2 accumulation in the same embryo. (K) Merged image of I and J (ABDA in green, MEF2 in red). (L) Merged image at limited optical sections to show co-expression in the mesoderm. ABDB was detected only in the posterior four nuclei of the dorsal vessel. Scale bars: 50 µm for A-C,E-G,I-K; 8 µm for D,H,L. All micrographs are dorsal views of stage 16 embryos with the anterior towards the left. The location of the heart (Ht) is bracketed in the lower magnification images.