Here's why:

* Golgi apparatus: This organelle acts like a processing and packaging center for the cell. It receives proteins and lipids from the endoplasmic reticulum (ER), modifies them, sorts them, and then packages them into vesicles.

* Exocytosis: The process of vesicles fusing with the plasma membrane and releasing their contents outside the cell is called exocytosis. This is how materials are transported out of the cell.

Important Note: Vesicles can also be formed at other locations within the cell, but those vesicles are typically involved in transporting materials within the cell, not out of it.