Uropod elongation is a common final step in all leukocyte subsets during extravasation. (A) The cremaster venules in Alexa Fluor 488–anti-Gr1 antibody–injected (i.v.) WT, LysM-GFP, and CX₃CR1-GFP mice were stimulated with chemokines (1 nM CXCL2 or CCL2) and 1 µM fMLP. The representative images of the cell elongation (top) and the cell lengths in each extravasation step (rolling, crawling, and extravascular [Ext.] retention; bottom) are shown. The cell lengths of each extravasating step were measured from at least five stimulated cremaster venules from three mice per stimulatory condition. Horizontal lines indicate the mean. *, P < 0.005. See corresponding Videos 2–4. (B) CFSE-labeled effector CD4 T cells were adoptively transferred to the WT recipient mice. The cremaster from the recipient mouse was stimulated with CXCL12 and IP10 and imaged using MP-IVM. The representative images of adhesion, interstitial migration, and elongation of the CD4 T cells are shown in the stimulated cremaster venules of the recipient mice. Cell morphology at each extravasating step was investigated from at least five stimulated cremaster venules from three mice. See corresponding Video 5. (C) MP-IVM was performed on the ear venules of LysM-GFP mice after PBS inoculation (Basal) or infection with C. albicans or L. major. A representative still image is shown among at least three basal and infected mice ear venule images for each condition. See corresponding Video 6. (A–C) The boxed areas indicate elongated leukocytes. Bars, 30 µm.