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Fig. 1. The Drosophila dorsal vessel consists of a posterior heart and an
anterior aorta, which can be distinguished on the basis of morphological and
molecular criteria. (A,C,E,G) Low-magnification views of stage 16 embryos
stained with various markers. (B,D,F,H) High-magnification views of same
embryos. (A,B) MEF2 protein accumulation in the muscle cells of the embryo.
The dorsal vessel consisted of two parallel rows of cells at the dorsal
midline. Note that the distance between the two rows of MEF2-positive nuclei
is greater in the heart (Ht) compared to the aorta (Ao). The pattern of
Hand transcripts (C,D) and muscle MHC protein (E,F) in the cardial
cells of the dorsal vessel can also be used to distinguish heart from aorta,
and to visualize the heart lumen. Numbered body segments are indicated. (G,H)
Tina-1 transcripts in the dorsal vessel accumulated only in the
heart. Scale bars: 50 µm for A,C,E,G; 25 µm for B,D,F,H. All pictures
are dorsal views oriented with anterior towards the left. In C,E,G, the
location of the heart is bracketed.