[Electron Micrograph of the Golgi complex. Notice the foldings that form the
cisternae. Copyright Daniel Kunkel]
The Golgi complex is composed of numerous sets of smooth cisternae, which are
coated with lipid membranes. Each disc-shaped cisternae forms a structure that
resembles a stack of plates, called a Golgi stack. The Golgi complex contains a
great number of vesicles. These vesicles are used to send molecules
to the cellular membrane, where they are excreted. There are also larger
secretory vesicles, which are used for selective excretion.
The Golgi is principally responsible for directing molecular traffic in the
cell - nearly all molecules pass through the Golgi complex at some point in
their existence. The sorting is mediated by the vesicles. When proteins bind
with their appropriate receptor on the vesicle, they are encoated in the vesicle
and transported away.