NETs are part of deep vein thrombi and histones produce toxicity in vivo. (A) A deep vein thrombus was formed in an otherwise healthy baboon by balloon catheterization. The thrombus was excised and analyzed for the presence of extracellular DNA (green) and von Willebrand factor (red), which were found to codistribute. Scale bar, 100 μm. Reproduced from Fuchs et al.³¹  (B) Intravenous histone infusion was detrimental to both endothelium and epithelium, as shown by vacuolization (stars) of these cells in and around the lung capillaries (right). Av, alveolae. Cav, caveolae. Ep-I, type I epithelial cell. EC, endothelial cell. Scale bars, 500 nm. Reproduced from Xu et al with permission.³⁰