Figure 4. Types of blood vessels stained with immunohistochemistry anti-CD31 in neuroblastoma samples.

Differences in blood vessel networks can be appreciated between sinusoids and capillaries. Sinusoidal networks are shown as discontinuous capillaries with more variable forms and sizes, irregular shapes and larger caliber (around 20 to 50 μm) than an ordinary capillaries. Capillary networks are composed by vascular tubes, measuring around 5-15 μm, lined with an uninterrupted layer of endothelial cells. The intrinsic design of the TMAs avoided areas with huge vascular structures so very few samples presented venules & arterioles and veins & arteries in their ECM (1.7% and 0.1% of all present blood vessels, respectively), thus these structures were not considered.