Final answer:
Intermediate filaments are found in the nuclear lamina and contribute to cell structure and resilience to tension. They help maintain the integrity and shape of the nucleus, support desmosomes, and are not part of structures like cilia, mitotic spindle, or centrosomes.
Step-by-step explanation:
Intermediate filaments, a type of cytoskeletal element, are found in various structures within the cell. Their primary function is to provide mechanical strength, resist tension, and maintain cell integrity. Specifically, intermediate filaments are known to form the nuclear lamina, a dense fibrillar network inside the nucleus of a cell that helps maintain the shape of the nucleus and is involved in organizing DNA. While they are associated with various cellular components, they are not present in structures such as cilia, mitotic spindle, cell cortex, or centrosomes; those are principally comprised of microtubules and microfilaments.
For example, intermediate filaments composed of the protein keratin are found in skin, hair, and nail cells. In muscle cells, the intermediate filament protein, desmin, is important in the formation of desmosomes that help cells resist external physical forces. While microtubules and microfilaments are involved in the formation of the mitotic spindle and cell cortex, respectively, it is the intermediate filaments that contribute to the structural support of the nuclear envelope and cell-to-cell junctions such as desmosomes.