What part of a cell controls water movement into and out of the cell?

If you know the answer, I would truly appreciate it if you answered my question. I am not sure if it is the cell membrane or not.

Furthermore, I am doing an experiment that demonstrates osmosis. We are using an egg to represent the cell. What part of the egg controls water movement into and out of the egg?

Thank you very much!What part of a cell controls water movement into and out of the cell?
it is in fact the cell membraneWhat part of a cell controls water movement into and out of the cell?
It IS the cell membrane. The phospolipids make it permeable to water and other small molecules.What part of a cell controls water movement into and out of the cell?
The contractile/normal vacuoles help the movement of water when in an isotonic state
the cell membrane, and the shell?