Specificity of early motoneuron growth cone outgrowth in the chick embryo
Open Access
- 1 September 1985
- journal article
- research article
- Published by Society for Neuroscience in Journal of Neuroscience
- Vol. 5 (9) , 2336-2344
- https://doi.org/10.1523/jneurosci.05-09-02336.1985
Abstract
During development, chick lumbosacral motoneurons have been reported to form precise topographic projections within the limb from the time of initial outgrowth. This observation implies, first, that motoneurons select the appropriate muscle nerve pathway and, second, that they restrict their ramification within the primary uncleaved muscle masses to appropriate regions. Several reports based on electrophysiology and orthograde horseradish peroxidase (HRP) labeling have shown muscle nerve pathway selection to be fairly precise. However, studies based on retrograde labeling with HRP have produced conflicting reports on the extent to which vertebrate motoneurons make projection errors. Since it is difficult to distinguish between true projection errors and HRP leakage when using retrograde labeling, we decided to assess the distribution of labeled growth cones in 25-micron serial plastic sections, following orthograde labeling of identifiable subpopulations of motoneurons during the period of initial axon outgrowth. Examination of a large number of muscle nerves revealed no segmentally inappropriate axons, confirming earlier reports that muscle nerve pathway selection is very accurate. In addition, we observed that growth cones take widely divergent trajectories into the same muscle nerve, suggesting that growth cones are responding independently to some specific environmental cue rather than being passively channeled at this point. The distribution of labeled growth cones within the muscle masses provided direct evidence that motoneurons did not at any time project to obviously inappropriate muscle regions.(ABSTRACT TRUNCATED AT 250 WORDS)This publication has 23 references indexed in Scilit:
- Motoneurone projection patterns in the chick hind limb following early partial reversals of the spinal cord.The Journal of Physiology, 1980
- Motoneurone projection patterns in embryonic chick limbs following partial deletions of the spinal cord.The Journal of Physiology, 1980
- Evidence that some developing limb motoneurons die for reasons other than peripheral competitionDevelopmental Biology, 1979
- Development of the segmental innervation of the chick forelimbDevelopment, 1979
- Development of functional motor innervation in supernumerary hindlimbs of the chick embryoJournal of Neurophysiology, 1978
- The development of motor projection patterns in the chick hind limb.The Journal of Physiology, 1978
- The projection patterns of the ventral horn to the hind limb during developmentDevelopmental Biology, 1976
- A series of normal stages in the development of the chick embryoJournal of Morphology, 1951
- The development and innervation of transplanted limb primordia of chick embryosJournal of Experimental Zoology, 1939
- The development of the thigh musculature of the chick twelve figuresJournal of Morphology, 1927