Disruption of Clec1b or Syk in the megakaryocyte/platelet lineage results in interconnection of the blood and lymphatic vasculatures. (A) FITC-dextran was injected into an anesthetized mouse via a carotid cannula after exteriorization of the abdominal mesentery. In both Clec1b^fl/fl (top) and Clec1b^fl/flPF4-Cre (bottom) FITC-dextran was initially visualized in the artery (1) followed shortly by the vein (2). In the Clec1b^fl/flPF4-Cre mice FITC-dextran was visualized in the mesenteric lymphatic vasculature (3) shortly after the flowing through the vein. This phenomenon was never seen in the Clec1b^fl/fl mice. Scale bar = 0.5 mm. This figure is representative of 3 experiments. (B) FITC-dextran was injected into the left ventricle of the heart of mice of the indicated genotypes, and vessels in the gut were visualized for FITC fluorescence 60 seconds later. FITC-dextran was only detected in the systemic blood circulation (1 and 2) of Syk^fl/fl (top left) and Syk^fl/flLysM-Cre mice (top right). In contrast, leakage of the FITC-dextran into the gut mesenteric lymphatic vasculature (3) was detected in Syk^fl/flVav-iCre (bottom left) and Syk^fl/flPF4-Cre (bottom right).