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Hindlimb sensory neuron number increases with body size
1Department of Physiology CB#7545, University of North Carolina School of Medicine, Chapel Hill 27599.
The Journal of Comparative Neurology
|April 15, 1994
Summary
As bullfrogs grow, their sensory systems add neurons to maintain sensitivity. Larger frogs have more dorsal root ganglion neurons, indicating neuron addition supports peripheral field expansion.
Area of Science:
- Neuroscience
- Developmental Biology
- Comparative Physiology
Background:
- Animal growth necessitates sensory system adaptation to expanding peripheral fields.
- Neuronal addition is crucial for maintaining sensory discrimination and localization precision.
Purpose of the Study:
- To quantify neuron numbers in bullfrog hindlimb dorsal root ganglia (DRGs) during growth.
- To investigate the relationship between body size and DRG neuron count in Rana catesbeiana.
Main Methods:
- Counting neuronal nuclei profiles in serially sectioned DRGs.
- Validating neuron counts with 3D reconstructions.
- Using horseradish peroxidase to trace peripheral nerve connections.
Main Results:
- Large frogs (10-17 cm) possessed over twice the DRG neurons of small frogs (3.3-5 cm).
- Neuron addition rate was highest between 3-8 cm body length.
- Added neurons were confirmed to extend axons to the periphery.
Conclusions:
- Bullfrog hindlimb sensory neuron number increases significantly with body size.
- Neuron addition is a key mechanism for adapting sensory systems to growth.
- This study supports the hypothesis of neuronal addition for peripheral field expansion.