Intermediate Filaments

Intermediate Filaments are the thickest in cytoskeleton family. Unlike microfilaments, they don't anchor to the plasma membrane. They move in the cytoplasm around the nucleus. Because they are the thickest, they serve an important role in the stability of the cell's shape, forming hair, skin, etc.

Keratin intermediate filaments (stained red)

Microscopy of keratin filaments inside cells, stained in red dye