Exocytosis is the reverse of endocytosis.

And that is just as well. In 30 minutes an active cell like a macrophage (right) can endocytose an amount of plasma membrane equal to its complete plasma membrane.

This electron micrograph (courtesy of Dr. Robert J. North) shows a guinea pig phagocyte ingesting polystyrene beads. Several beads are already enclosed in vacuoles while the others are in the process of being engulfed.

So the cell must have a mechanism to restore the normal