Endocytosis is the uptake of extracellular macromolecules across the plasma membrane into the cell. The objects to be ingested is progressively enclosed by a small portion of the plasma membrane that first invigilates and then pinches off to form an intracellular vesicle having the ingested macromolecule. Endocytosis can be divided into three distinct parts depending on the size of the ingested macromolecule and whether particular cell surface receptors are included. These 3 procedures are receptormediated, endocytosis pinocytosis, and phagocytosis.