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Axonal branching and growth cone structure depend on target cells
S A Berman1, D Moss, S Bursztajn
1Department of Psychiatry (Neuroscience), Harvard Medical School, Cambridge, Massachusetts 02138.
Developmental Biology
|September 1, 1993
Summary
Muscle cells significantly alter neuronal growth, increasing axon numbers and reducing growth cone size in developing neurons. This highlights the influence of target tissues on neural development and axon guidance.
Area of Science:
- Neuroscience
- Developmental Biology
- Cell Biology
Background:
- Growth cones are essential for guiding neuronal development.
- Neurons respond to environmental cues and target cells for proper guidance.
- Understanding target-specific neuronal growth is key to regenerative medicine.
Purpose of the Study:
- To investigate how ciliary neuron growth cones change upon contacting muscle cells (myotubes).
- To characterize alterations in axon patterns and growth cone morphology in response to target contact.
- To determine the role of muscle cells in regulating neuronal axon growth and topography.
Main Methods:
- Coculturing ciliary neurons with myotubes and fibroblasts.
- Utilizing immunofluorescence microscopy with antibodies for GAP-43 and MAP-2.
- Quantifying axon numbers, growth cone size (lamellipodia area), and filopodia count.
Main Results:
- Ciliary neurons cocultured with myotubes developed significantly more axons (4-5) compared to those alone (1-2).
- Growth cone lamellipodia area decreased substantially when contacting myotubes (25.0 μm²) versus alone (56.3 μm²).
- The number of filopodia per growth cone was lower in nerve-muscle cocultures (3.6) than in cultures without myotubes (6.8).
Conclusions:
- Muscle cells or their secreted factors actively regulate neuronal growth cone morphology and axon branching.
- Target tissues play a critical role in shaping neuronal projections during development.
- These findings have implications for understanding neural regeneration and development.