The cells - human, vegetable or animal - have doorways, like a room in a house comprises a door: Aquaporins.

These doors are privileged places of passage and can be opened with special keys.

If we use:

- a less concentration, giving a "osmolar gradient" (a move) from outside towards inside of the cell,

- a key opening the door

We "inject" liquid into the cell. Adipocyte can enlarge from 30 to 40 times its size.
Weakened by this growth, we can break it by massage.