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The precision of pathway selection by developing peripheral axons in the axolotl
Journal of Embryology and Experimental Morphology
|February 1, 1986
Summary
Axolotl hindlimb development shows directed nerve growth. Axons preferentially grow via ventral rami, indicating a strong attraction guides this precise pathway selection.
Area of Science:
- Developmental biology
- Neuroscience
- Axolotl biology
Background:
- Trunk innervation in axolotls involves segmental nerves with dorsal and ventral rami.
- During hindlimb development, numerous axons must grow via ventral rami to reach the limb.
Purpose of the Study:
- To determine the precision of pathway selection by axons during axolotl hindlimb innervation.
- To investigate whether axon outgrowth is directed or random during limb development.
Main Methods:
- Counting axons in dorsal and ventral rami at limb and non-limb segmental levels.
- Comparing axon ratios and numbers before and during peak axon proliferation for hindlimb innervation.
Main Results:
- A tenfold increase in the ventral/dorsal ramus axon ratio was observed during peak hindlimb outgrowth.
- No significant increase in dorsal ramus axons at limb levels, while non-limb levels showed a fourfold increase.
- Axon growth appears highly directed towards the limb, suggesting a strong, non-specific attractive force.
Conclusions:
- Axon outgrowth during axolotl hindlimb development is a highly directed process, not random.
- A potent attractive mechanism likely guides axons into the ventral ramus to innervate the developing limb.