Figure 7 of Kagemann, Mol Vis 2008; 14:2157-2170.

Figure 7. Blood within vessels creates shadow artifacts in C-mode slices below the vessels. Images of the same 48 hpf embryo obtained in a shallow slab location (A) and a deep location (B) allow visualization of blood, which is highly scattering (A, bright locations, arrows), and the resultant shadows mask structure in deeper slabs (B, dark locations, arrows).