Cells engage in endocytosis and exocytosis. Cells can import materials from the external medium by capturing them in vesicles that pinch off from the plasma membrane. The vesicles ultimately fuse with lysosomes, where intracellular digestion occurs. By a converse process, cells export materials that they have synthesized in intracellular compartments: the materials are stored in the intracellular vesicles and released to the exterior when these vesicles fuse with the plasma membrane.  Fair Use and Copyright info