Jak2^V617F mice showed an enhanced early endothelial adhesion of leukocyte and platelet in cerebral veins after CVST. (A) Intravital microscopy imaging of venous brain network from Jak2^WT and Jak2^V617F mice representing SSS and cortical venules (CtV) labeled with dextran 2 mKDa (green). Scale bar, 200 μm. (B) In sham-operated mice (left panel), sparse marginating leukocytes and platelets (rhodamine 6G, red) were found in Jak2^V617F and Jak2^WT mice. Two hours after CVST, adhesion and accumulation of platelets and leukocytes increased in both Jak2^V617F and Jak2^WT mice (right panel). Dextran imaging showed black segments within venules (white arrow), indicating a disruption in blood flow and formation of new thrombi. (C) Median of fluorescence intensity of rhodamine 6G–labeled platelets and leukocytes as a marker of thrombosis burden in CtV. Results are expressed as mean ± standard deviation (n = 5 per group). Data were analyzed using Kruskal-Wallis test; ∗P < .05; ∗∗P < .01. (D) Labeling of neutrophils (Ly6G, pink; lower panel) and vessels (dextran 2 mKDa, green; upper panel) showed that neutrophils were mainly involved in endothelial adhesion in Jak2^V617F mice. Scale bars, 25 μm.