Here's why:

* Network of protein fibers and tubes: The cytoskeleton is made up of three main types of protein fibers: microtubules, microfilaments (actin filaments), and intermediate filaments. These fibers extend throughout the cytoplasm.

* Extending through the cytoplasm: The cytoskeleton provides structural support and organization to the cell. It helps maintain cell shape, allows for movement, and facilitates transport of substances within the cell.

Let me know if you have any other questions!