Schwann Cells In Peripheral Myelination is an important cell type in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
Schwann cells are the myelinating cells of the peripheral nervous system (PNS), responsible for forming the myelin sheath around axons in the PNS. Unlike oligodendrocytes in the central nervous system (CNS), each Schwann cell myelinates a single axon segment. Schwann cells are essential for rapid nerve conduction in the PNS, and their dysfunction underlies peripheral neuropathies including Charcot-Marie-Tooth disease and Guillain-Barré syndrome.
| Property |
Value |
| Category |
Glial cells |
| Location |
Peripheral nervous system (PNS) |
| Cell Type |
Myelinating Schwann cell |
| Origin |
Neural crest cells |
| Function |
Myelin formation, axonal support, nerve conduction |
¶ Development and Lineage
Schwann cells derive from neural crest cells during embryonic development:
- Neural Crest Progenitors: Migrate along developing nerves
- Immature Schwann Cells: Proliferate and associate with axons
- Pro-myelinating Schwann Cells: Initiate myelination program
- Myelinating Schwann Cell: Form compact myelin sheath
- Non-myelinating Schwann Cells: Remain associated with small axons
- Neuregulin-1 (NRG1): Essential for Schwann cell survival and myelination
- Notch signaling: Regulates myelination choice
- cAMP: Promotes myelination
- PI3K/AKT: Cell survival pathway
- Elongated cell body along axon
- Multi-layered myelin wrap (up to 75 layers)
- Internode: Myelinated segment (500-1500 μm)
- Node of Ranvier: Unmyelinated gap (1-2 μm)
- C Schmidt-Lanterman incisures: Cytoplasmic channels
- Microvilli: At nodes of Ranvier
- Surround multiple small axons
- Form Remak bundles
- Do not produce compact myelin
PNS myelin differs from CNS myelin:
- Periodic myelin segments: Distinct from internodes
- Schmidt-Lanterman incisures: Cytoplasmic clefts
- Microvilli at nodes: For ion exchange
- Basal lamina: Surrounds Schwann cells
Major PNS myelin proteins:
- P0 (MPZ): Adhesion molecule, 50% of PNS myelin protein
- MBP: Present but less abundant than in CNS
- PMP22: Peripheral myelin protein 22
- Peripheral myelin protein 2 (PMP2)
- Connexin-32 (GJB1): Gap junctions
Schwann cells enable rapid nerve conduction:
- Myelin insulates axons in the PNS
- Action potentials jump between nodes
- Conduction velocity increases 50-100x
- Node of Ranvier enriched in sodium channels
Schwann cells provide critical axonal support:
- Produce neurotrophic factors (BDNF, NGF, GDNF)
- Maintain axonal cytoskeleton
- Clear debris after injury
- Guide axonal regeneration
During development, Schwann cells:
- Guide growing axons
- Promote axonal sorting
- Establish nodal architecture
- Form neuromuscular junctions
Inherited peripheral neuropathies:
- Gene: PMP22 duplication
- Pathology: Demyelination, onion bulb formation
- Onset: Childhood
- Features: Distal weakness, foot deformities
- Gene: GJB1 (Connexin-32)
- X-linked inheritance
- Features: Variable severity
- Primary axonal degeneration
- Less severe than demyelinating forms
Autoimmune peripheral neuropathy:
Pathology:
- Autoantibodies against peripheral nerve antigens
- Demyelination or axonal damage
- Acute inflammatory demyelinating polyradiculoneuropathy
Subtypes:
- AIDP (acute inflammatory demyelinating)
- Miller Fisher syndrome (anti-GQ1b)
- Axonal forms (AMAN, AMSAN)
Treatment:
- Intravenous immunoglobulin (IVIG)
- Plasma exchange
- Supportive care
- Chronic progressive or relapsing-remitting
- Similar to GBS but longer duration
- Requires sustained treatment
- Most common peripheral neuropathy
- Metabolic dysfunction of Schwann cells
- Microvascular damage
- Axonal degeneration
Schwann cells respond to injury:
- Distal axon degenerates
- Schwann cells clear debris
- Form Bands of Bungner
- Guide axon regrowth
- Re-myelinate regenerating axons
- Support functional recovery
Schwann cells can remyelinate after injury:
- Dedifferentiation of surviving Schwann cells
- Proliferation
- Re-myelination of axons
- More efficient remyelination
- Thinner myelin (shadow fibers)
- Functional recovery possible
Schann cells exhibit diversity:
- Myelinating Schwann cells
- Non-myelinating Schwann cells (Remak cells)
- Terminal Schwann cells (at synapses)
- Sensory vs. motor nerve differences
- Node of Ranvier architecture
- Myelin thickness variation
Schwann cell markers:
- S100β (Calcium-binding protein)
- P75NTR (p75 neurotrophin receptor)
- GFAP (in immature/non-myelinating)
- MBP (myelin basic protein)
- MPZ (Myelin Protein Zero)
- Corticosteroids: For CIDP
- IVIG: For GBS and CIDP
- Plasma exchange: For GBS
- Immunomodulatory drugs
- Gene therapy: For CMT
- Neurotrophic factors: Promote survival
- Cell therapy: Stem cell-derived Schwann cells
- Small molecules: Promote myelination
| Feature |
PNS (Schwann cells) |
CNS (Oligodendrocytes) |
| Cell type |
Schwann cell |
Oligodendrocyte |
| Myelination |
One axon per cell |
Up to 60 axons per cell |
| Node length |
500-1500 μm |
200-2000 μm |
| Basal lamina |
Present |
Absent |
| Incisures |
Schmidt-Lanterman |
Absent |
| Remyelination |
Efficient |
Limited |
| Immune response |
More robust |
More limited |
The study of Schwann Cells In Peripheral Myelination has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.
- Jessen & Mirsky, The origin and development of glial cells (2005) - Developmental Dynamics
- Salzer, Schwann cell myelination (2015) - Cold Spring Harbor Perspectives
- Nave & Trapp, Axon-glial signaling (2008) - Annual Review of Neuroscience
- Feltri & Wrabetz, Myelin assembly (2005) - The Neuroscientist
- Martini et al.,Schwann cell response to injury (2008) - Acta Neuropathologica
- Scherer & Wrabetz, Molecular basis of Charcot-Marie-Tooth disease (2008) - Neuromuscular Disorders
- Patzkó & Shy, Update on Charcot-Marie-Tooth disease (2011) - Archives of Neurology
- Rajabally & Durand, Treatment of CIDP (2015) - Revue Neurologique