The Golgi stack occupies the cross-roads of membrane traffic in the cell, at the interface between protein export from the ER and import by endocytosis. Many different kinds of transport vesicles bud from and fuse with the stack at various levels.
Overall, the stack operates as an iterative sorting device, separating proteins in stages as they progress forward or backward across it stack.
Yet, there are many basic questions about how this traffic flow is orchestrated and even its very nature.
New dynamic imaging technologies, such as super-resolution optical imaging, are being used to probe these questions.