Preferential extravasation of neutrophils in platelet-rich areas of cremasteric venules. (A) Confocal intravital microscopy of cremasteric venules in LysM-eGFP mice that were injected intrascrotally with IL-1β. Endothelial cells and platelets were labeled through IV injection of fluorophore-coupled anti–PECAM-1 and anti–GPIbβ antibodies, respectively. Mice were anaesthetized, the cremaster muscle was prepared for intravital imaging, and videos were taken for 1 to 1.5 hours. White dots mark platelets bound to the endothelium, the filled arrowhead marks areas of neutrophil extravasation, and the open arrowhead marks areas of extravasation (supplemental Video 1). Scale bars, 10 µm. The timestamp of the video is 0:20:41:943. (B) Quantification of neutrophil transmigration in platelet-rich and platelet-poor areas of cremasteric venules from 10 videos shown as the percentage of total transmigrated neutrophils. Data are mean ± SEM. (C) Correlation analysis (Pearson) and linear regression of transmigrated neutrophils and endothelium-bound platelets in videos, as described in (A). Results are representative of (A) or pooled from (B-C) 10 videos taken of 9 mice. ***P < .001, Mann-Whitney rank test.