Fig. 5. Contribution of macrophages to Matrigel vascularization. Sections of 5 day (A-D) and 9 day (E-H) Matrigel plugs were stained for DAPI (blue), NG2 (magenta), CD31 (green) and F4/80 (red) to investigate the presence of macrophages in developing vessels. At day 5, NG2⁺F4/80^- pericytes are present (arrowhead). Some F4/80⁺ macrophages also express NG2 (arrow), while others are NG2^- (asterisk). At day 9, NG2 and F4/80 are expressed on non-overlapping populations of pericytes and macrophages, respectively. At this stage, pericytes (arrowhead) exhibit a more intimate physical relationship with endothelial cells than macrophages do (arrows). All panels represent z-stacks of confocal images. Sale bars: 40 µm.