Glycogen is stored in the cytoplasm of cells, specifically in granules called glycogen granules.

Here's a breakdown:

* Cytoplasm: The gel-like substance that fills the cell and surrounds the nucleus.

* Glycogen granules: These are small, dense structures within the cytoplasm where glycogen molecules are clustered together.

The highest concentrations of glycogen are found in:

* Liver cells (hepatocytes): The liver stores glycogen as a readily available source of glucose for the body.

* Muscle cells: Muscle cells store glycogen for their own energy needs during exercise.