<P> In cell biology , a vesicle is a small structure within a cell , or extracellular , consisting of fluid enclosed by a lipid bilayer . Vesicles form naturally during the processes of secretion ( exocytosis ) , uptake ( endocytosis ) and transport of materials within the cytoplasm . Alternatively , they may be prepared artificially , in which case they are called liposomes ( not to be confused with lysosomes ) . If there is only one phospholipid bilayer , they are called unilamellar liposome vesicles ; otherwise they are called multilamellar . The membrane enclosing the vesicle is also a lamellar phase , similar to that of the plasma membrane and vesicles can fuse with the plasma membrane to release their contents outside the cell . Vesicles can also fuse with other organelles within the cell . </P>
<P> In cell biology , a vesicle is a small structure within a cell , or extracellular , consisting of fluid enclosed by a lipid bilayer . Vesicles form naturally during the processes of secretion ( exocytosis ) , uptake ( endocytosis ) and transport of materials within the cytoplasm . Alternatively , they may be prepared artificially , in which case they are called liposomes ( not to be confused with lysosomes ) . If there is only one phospholipid bilayer , they are called unilamellar liposome vesicles ; otherwise they are called multilamellar . The membrane enclosing the vesicle is also a lamellar phase , similar to that of the plasma membrane and vesicles can fuse with the plasma membrane to release their contents outside the cell . Vesicles can also fuse with other organelles within the cell . </P>
where do vesicles originate that are involved in secretion
where do vesicles originate that are involved in secretion
within a cell
within a cell