Shown to the right is an animation which illustrates how membrane flows through the stack of Golgi cisternae. Note throughout this process that the newly synthesized membrane "flows" along with the newly synthesized proteins. Membrane is synthesized by the combined action of the RER and SER. The RER synthesizes membrane proteins as well as proteins destined for secretion. The SER synthesizes membrane lipids. Thus, new memrane is synthesized and leaves the SER as vesicles which move on to the Golgi where they coelesce together at the forming face of the Golgi. The animation begins as the vesicles from the SER approach the Golgi. The membrane moves sequentially through the Golgi cisternae and leaves the Golgi at the maturing face as secretion vesicles bleb off. The SV move away from the Golgi and will later fuse with the plasma membrane (not shown here, but see the membrane fusion animation) and dump their contents (the soluble proteins synthesized in the RER) outside of the cell.