CD34 and neoplasm: Finally, the analysis of angiogenesis markers showed that poly I:C treatment was followed by a change in vessel morphology, loss of well-structured walls and flimsy appearance and by a massive reduction in the density of CD34 positive tumour vessels (7 ± 3 versus 19 ± 5 vessels/mm2 of tumour surface, P < 0.0001; Fig.7B and C).