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6.8.2. Intermediate filaments

Intermediate filaments

The intermediate filaments are composed of protein, thick and resilient fibers, which are named to have a thickness (8-10 nm) intermediate between the microfilaments and the microtubules.

1 nm (nanometer) = 10 Å (angstrom) = 1 × 10-9 meters = 1 × 10-6 millimeters

Structure and composition of the intermediate filaments

The intermediate filaments are formed by structures fibrous proteins, very resilient, which are found in all eukaryotic cells. They are the most stable components of the cytoskeleton. Four types stand out:

  • Keratin filaments. They are called tonofilaments and are characteristic of epithelial cells, to which they provide a lot of mechanical resistance. They also appear in epithelial cell cell-junction desmosomes.
  • Neurofilaments. The neurons contain neurofilaments in the axon.
  • Vimentin filaments, typical of connective tissue cells.
  • Desmin filaments, very abundant in muscle cells.

Functions of intermediate filaments

Intermediate filaments are the strongest of the three types that make up the cytoskeleton. Its main function is to support the cellular organelles and thus provide mechanical resistance to the cell, avoiding the rupture of the membranes of the cells subjected to stress.

For this reason, they are abundant in nerve fibers and muscle and epithelial cells that are subjected to strong stresses.

Like the rest of the components of the cytoskeleton, they contribute to the maintenance of cell shape.