Pinocytosis

In cellular biology, pinocytosis (pino- + cytosis), otherwise known as cell drinking, fluid endocytosis, and bulk-phase pinocytosis, is a mode of endocytosis in which small particles are brought into the cell, forming an invagination, and then suspended within small vesicles. These pinocytotic vesicles subsequently fuse with lysosomes to hydrolyze (break down) the particles. This process requires a lot of energy in the form of adenosine triphosphate (ATP), the chemical compound mostly used as energy in the majority of animal cells.