MICROFILAMENTS
Microfilaments are fibres of the protein actin 4 to 7 nanometers in diameter in the cytoplasm of eukaryotic cells. Microfilaments form a compact interlacing under the plasma membrane. They are organized into bundles of parallel oriented fibres in the cell cytoplasm. Microfilaments are retractile elements of the cytoskeleton and they are immediately involved in the change of cell shape.