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Postnatal development of olfactory receptor cell axonal arbors
1Department of Neurosurgery, Yale University School of Medicine, New Haven, Connecticut 06520-8082, USA.
The Journal of Comparative Neurology
|February 7, 1998
Summary
Olfactory receptor neuron axons achieve adult patterns without early overgrowth. This suggests direct guidance mechanisms, not pruning, shape their specific glomerular innervation.
Area of Science:
- Neuroscience
- Developmental Biology
- Olfactory System Research
Background:
- The precise mechanisms guiding olfactory receptor neuron (ORN) axon terminal arborization in the olfactory bulb are not fully understood.
- Common central nervous system development involves axonal exuberance followed by activity-dependent pruning.
Purpose of the Study:
- To investigate whether ORN axonal arbors in the olfactory glomerulus follow a developmental pattern of initial exuberance and subsequent pruning.
- To characterize the morphological development of ORN axonal arbors from postnatal day 0 to 21.
Main Methods:
- Studied Sprague-Dawley rat olfactory bulbs at multiple postnatal ages (0, 3, 6, 9, 12, 21 days).
- Utilized Golgi staining to impregnate ORN axons.
- Reconstructed and morphometrically analyzed axonal arbors using camera lucida at high magnification.
Main Results:
- ORN axonal arbor morphology in younger rats was not statistically different from adult patterns.
- No evidence of early axonal exuberance was observed.
- Adult ORN axons occupied approximately 14% of glomerular area with specific branch lengths and varicosity counts.
Conclusions:
- ORN axons likely innervate single glomeruli and arborize to adult levels directly, without a phase of exuberance and pruning.
- This suggests that specific cell surface molecules and trophic factors play a crucial role in guiding glomerular targeting and precise innervation by ORN axons.