Figure 4.

Rod-shaped monocytes can cross the cerebral endothelium and extend cytoplasmic processes. a, b, Confocal images of GFP⁺ monocytes (green; arrows) that seemed to be in the process of migrating through the endothelium (red). Scale bars: a, 5 μm; b–g, 10 μm. c, Two monocytes, one (arrow) that was located in a capillary and the other (arrowhead) in the parenchyma. Note that the latter had a polarized shape typical of migrating cells, with a leading edge (bottom) and uropod (top). d–f, Monocyte-derived perivascular macrophages exhibiting an elongated cell body with cytoplasmic processes. Note the typical shape of the nucleus in f. g, Monocyte that extended a long cytoplasmic process in a capillary.