Pinocytosis

Unlike the phagocytosis, that is a regulated form of endocytosis carried out through a small number of cell category, pinocytosis is a constitutive process which occurs continuously in all eukaryotic cells.  Little areas of the plasma membrane are ingested in the form of small pinocytic vesicles that are later returned to the cell

                                                       Figure: (a) Phagocytosis and (b) pinocytosis.

surface.  By the pinocytic vesicle forms, a little amount of extracellular fiuid is enclosed in the vesicle and also taken up into the cell which is described in the figure. That nonspecific uptake of extracellular fiuid is frequently denotes to as cell-drinking or fiuid-phase endocytosis. The initial endocytosis starts through the formation of a clathrin-coated pit at specialized regions of the plasma membrane. The resulting clathrin-coated endocytic vesicle or endosome is then endocytosed the clathrin coat dissociates; the endosome fuses with a lysosome.