Final answer:
The cell cortex in eukaryotic cells is primarily made up of actin filaments, also called microfilaments, which are key to maintaining cell shape and supporting movement.
Step-by-step explanation:
In eukaryotic cells, the cell cortex is made of a network of actin filaments. These actin filaments, also known as microfilaments, are the narrowest components of the cytoskeleton and are fundamental for maintaining the cell's shape and facilitating movement. Microfilaments are particularly abundant just beneath the cell membrane, forming a thickened cortex around the cell's inner edge, which is crucial for cell morphology and motility. Furthermore, these protein fibers are involved in important cellular processes, such as cytokinesis during cell division where they enable the contracting mechanism of the cleavage furrow.
The other cytoskeletal fibers include intermediate filaments and microtubules. Intermediate filaments, composed mainly of proteins like keratin, play a role in resisting tension, anchoring organelles, and connecting cells to one another. Meanwhile, microtubules, which are the thickest of the cytoskeletal structures and are composed of alpha and beta-tubulin, help in maintaining cell shape, intracellular transport, as well as cilia and flagella movement.