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How is the Golgi apparatus structured as a stack of cisternae?

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Diagram of the Golgi apparatus showing its stacked, curved membranes with labeled parts including cisternae, cis face, trans face, lumen, and various vesicles involved in cellular transport and secretion. — Golgi apparatus A membrane-bound organelle of eukaryotic cells, the Golgi apparatus is made up of a series of flattened, stacked pouches called cisternae that function as a series of compartments that progressively refine and direct cellular products to their proper destinations. .

The Golgi apparatus is a membrane-bound organelle characterized by a series of flattened, disk-shaped, membrane-defined pouches known as cisternae. Typically, the apparatus consists of four to eight of these cisternae arranged in a stack, though some single-celled organisms may contain as many as 60.21

The structure is held together by matrix proteins and supported by cytoplasmic microtubules. It is also structurally polarized, featuring three distinct functional compartments:2

Cis face: The region nearest the endoplasmic reticulum, where proteins and lipids are received.21
Medial segment: The central layers of the stack.2
Trans face: The region farthest from the endoplasmic reticulum, where molecules are sorted and packaged into vesicles for transport.21

These compartments are biochemically distinct, with each containing specific enzymes required for the modification of proteins and lipids as they progress through the stack.21