Phagocytosis is a kind of endocytosis to absorb some relatively large particles (microorganisms, dead and destroyed cells or debris, inert materials such as silicon salts, carbon, etc.) Phagocytosis of these objects by professional phagocytic cells (such as macrophages or neutrophils) is a receptor-mediated and regulated process. A contact between a phagocytic cell and the object to be absorbed activates the cell cytoskeleton causing formation of elongated projections, villi, and folds of the cellular surface. The image depicts projections of a macrophage #1, #2 wrapping the cellular debris. Subsequently, the absorbed material is further enveloped into a phagosome, which is a relatively large vacuole. The phagosome matures for a while, then joining a primary lysosome, which is a transporting vesicle transferring hydrolytic enzymes from Golgi apparatus. The diversity of cell lysosomes in an actively functioning macrophage is generally due to secondary lysosomes (phagolysosomes). For more details, see "Cytoplasmic fragment of macrophage"