Figure 4

(A) Sickle-shaped blood vessels as observed after H&E staining. Possibly, due to weak vascular support structures, irregular stenosis (red circle) caused by surrounding tumor cell growth (orange arrow) and pressure on the intervening vessels (blue arrow) can be observed. The tumor may be growing as multiple mountainous protrusions within the dilated vessels, causing valleys between them, steep bifurcations, and sharp angles at the tips. (B) Sickle-shaped blood vessels in CD31-stained cells. CD31-positive endothelial cell covering is shed in some of the intravascular protrusions (red arrow).