Alveolar macrophage, coloured scanning electron micrograph (SEM). B2 sample (sucrose fix) of rat alveolar macrophage and three micrometre particle phagocytosis. Also seeb are three macrophages with surface beading. The alveolar tissue macrophage has short filopodia. A tissue macrophage is a large, mature phagocyte that can ingest and destroy invading microbes, foreign particles, cancerous or diseased cells and cellular debris. Alveolar (lung pleural cavity) macrophages are part of the reticuloendothelial system. Magnification: x500 when shortest axis printed at 25 millimetres.