When eukaryotic cells are placed in the following solutions the changes observed are as follows:

Hypotonic Solution: The water moves from a region of low osmolarity to a region of high osmolarity. In this case, since the extracellular fluid has low osmolarity, the water would rush into the cell. The cell would then expand and eventually lyse or burst.

Hypertonic Solution: In this case, water will leave the cell since the cell has a lower osmolarity than the extracellular fluid. As a result the cell would shrink in what is called plasmolysis.

Isotonic Solution: The osmolarity of both fluids is equal. As such, though water diffuses in and out, there is no net change in the volume of the cell.