Cytoskeleton: microfilaments, intermediate filaments, microtubules !
- Topic
The cytoskeleton is the cell's inner scaffold: it gives shape, moves the cell and shares out the chromosomes when it divides.
Updated 2026-11-01
See it in 3D: Skin
What it is
The cytoskeleton is a network of three kinds of protein filament. Actin microfilaments move and shape the cell, intermediate filaments resist tension, and tubulin microtubules act as rails for transport and build the mitotic spindle, cilia and flagella. Several drugs and diseases act on it.
Function
- Motor proteins walk along microtubules: kinesin carries cargo toward the plus end (anterograde, toward the axon terminal) and dynein toward the minus end (retrograde).
- Microtubules grow from the centrosome, which holds two centrioles of nine triplets.
- Myosin pulls on actin filaments for muscle contraction and to pinch the cell in two at cytokinesis.
The three filaments
| Filament | Diameter | Protein | Function | Clinical |
|---|---|---|---|---|
| Microfilament | About 7 nm (thinnest) | Actin | Core of microvilli, contraction with myosin, cytokinesis ring, cell migration | Wiskott-Aldrich syndrome (actin regulation) |
| Intermediate filament | About 10 nm | Keratins, vimentin, desmin, GFAP, neurofilaments, nuclear lamins | Resists tension; anchors desmosomes and hemidesmosomes | Epidermolysis bullosa simplex (keratins 5 and 14); tumour markers |
| Microtubule | About 25 nm (thickest), hollow tube | Alpha and beta tubulin | Mitotic spindle, vesicle transport, cilia and flagella | Colchicine, vinca alkaloids and taxanes; primary ciliary dyskinesia |
Markers
- Cytokeratin: epithelia and carcinomas
- Vimentin: mesenchyme and sarcomas
- Desmin: muscle
- GFAP: astrocytes and gliomas
- Neurofilament: neurons
Clinical notes
- Colchicine blocks microtubule polymerisation in neutrophils and dampens gouty inflammation.
- Vinca alkaloids (block assembly) and taxanes (block disassembly) halt mitosis in tumour cells; peripheral neuropathy is a typical side effect.
- Epidermolysis bullosa simplex: faulty keratins 5 and 14; basal cells break with friction and blisters form.
Test yourself
Think of the answer, then tap the question to see it.
Which intermediate filament identifies a tumour of epithelial origin on immunohistochemistry?
Cytokeratin; vimentin points to mesenchymal origin, desmin to muscle and GFAP to glia.
Which motor protein carries cargo toward the neuron's cell body (retrograde transport)?
Dynein, which moves toward the minus end of microtubules.
How do taxanes act on microtubules?
They stabilise microtubules and prevent disassembly, which arrests the cell in mitosis.
Which proteins fail in epidermolysis bullosa simplex?
Keratins 5 and 14 of the basal keratinocytes, intermediate filaments that resist friction.
See it in 3D
The structures of Durgical's 3D anatomy where it is found.
Related
- Cilia, microvilli and stereocilia
- Cell junctions: tight, adherens, desmosomes, gap, hemidesmosomes
- Cell cycle, mitosis and meiosis
- Skeletal muscle: sarcomere and contraction
- The neuron and synapse
In Pharmacology
Educational content on normal microscopic structure and its clinical relevance; no substitute for studying slides or for a health professional's advice.
Sources: 3.2 The Cytoplasm and Cellular Organelles (OpenStax (Rice University), 2022); 3.5 Cell Growth and Division (OpenStax (Rice University), 2022); Epidermolysis bullosa simplex (MedlinePlus Genetics (U.S. National Library of Medicine), 2024).
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Representative model, for educational purposes only.