Figure 6-43.
Looking down on the head of a stage 35–36 embryo. The beating heart appears as a structure between the anterior head and the large oil droplet on the right (see also Movie M6-2g). Scale bar, 250 μm.

Figure 6-44.
Gene expression of mcmlc2 in a stage 35–36 embryo, as detected by whole-mount in situ hybridization. mcmlc2 expression can be seen in both the atrium and the ventricle. Scale bar, 250 μm.