The pattern of innervation in serially duplicated axolotl limbs: further evidence for the existence of local pathway cues?

Development ◽  
1987 ◽  
Vol 100 (3) ◽  
pp. 479-487
Author(s):  
N. Stephens ◽  
N. Holder
Keyword(s):  
Spinal Cord ◽  
Horseradish Peroxidase ◽  
Local Environment ◽  
Retrograde Transport ◽  
Limb Muscle ◽  
Biceps Muscle ◽  
Motor Innervation ◽  
Nerve Sprouting ◽  
Correct Pattern ◽  
Motor Neurones

The innervation of the biceps muscle was examined in regenerated and vitamin A-induced serially duplicated axolotl forelimbs using retrograde transport of horseradish peroxidase. The regenerated biceps muscle becomes innervated by motor neurones in the same position in the spinal cord as the normal biceps motor pool. In previous experiments in which the innervation of a second copy of a proximal limb muscle was examined in serially duplicated limbs (Stephens, Holder & Maden, 1985), the duplicate muscle was found to become innervated by motor neurones that would normally have innervated distal muscles. In the present study, the innervation of the second copy of biceps was examined under conditions designed to encourage nerve sprouting from ‘correct’ biceps axons. Following either partial limb denervation or denervation coupled with removal of the proximal biceps, the second copy of the muscle was still innervated by inappropriate motor neurones, which again would normally innervate distal limb muscles. These results are interpreted as evidence for the necessity for an appropriate local environment for axonal growth to allow reformation of a correct pattern of motor innervation in the regenerated limb.

Reformation of specific neuromuscular connections during axolotl limb regeneration: evidence that the first contacts are correct

Development ◽  
1988 ◽  
Vol 103 (2) ◽  
pp. 365-377
Author(s):  
S. Wilson ◽  
M. Jesani ◽  
N. Holder
Keyword(s):  
Spinal Cord ◽  
Horseradish Peroxidase ◽  
Limb Regeneration ◽  
Microscopic Analysis ◽  
Motor Neurone ◽  
Extensor Digitorum ◽  
Limb Muscle ◽  
Proximal Muscle ◽  
Electron Microscopic ◽  
Neuronal Tracing

Retrograde neuronal tracing with horseradish peroxidase was used to determine the position in the spinal cord of the motor neurone pools of a proximal (biceps) and a distal (extensor digitorum) limb muscle at various times during axolotl limb regeneration. It was found that from the earliest stages of muscle redifferentiation (as judged by light and electron microscopic analysis) the vast majority of axons innervating the regenerating muscles came from cells within the bounds of the normal motor neurone pool for each muscle. A few incorrect projections were noted in that the regenerating proximal muscle was sometimes innervated by some cells caudal to its normal motor neurone pool. The results are discussed in terms of mechanisms that may be operating in the regenerating limb to ensure that specific neuromuscular connections are made.

Motorneuron pools innervating muscles in vitamin A-induced proximal-distal duplicate limbs in the axolotl

1985 ◽  
Vol 224 (1236) ◽  
pp. 341-354 ◽  
Keyword(s):  
Horseradish Peroxidase ◽  
Vitamin A ◽  
Nerve Regeneration ◽  
Retrograde Transport ◽  
Axonal Guidance ◽  
The Other ◽  
Limb Muscle ◽  
Hindlimb Muscle ◽  
Forelimb Muscles ◽  
Distal Limb Muscle

Serially duplicated limbs containing two sets of proximal muscles were created in axolotls by vitamin A treatment. The innervation of three replicated proximal muscles was studied by using retrograde transport of horseradish peroxidase. These were the forelimb muscles biceps (seven cases) and anconeus (five cases) and the hindlimb muscle puboischiotibialis (five cases). In two cases (both of anconeus) innervation was from a correct motorneuron pool. In the other 15 cases the innervation was from an incorrect, distal limb muscle, motorneuron pool. These results are interpreted as evidence against long range signals between nerve and muscle controlling specific nerve regeneration. However, the data are compatible with models of axonal guidance that use local pathway cues.

Motor innervation of proximally rotated chick embryo wings

Development ◽  
1984 ◽  
Vol 83 (1) ◽  
pp. 213-223
Author(s):  
N. G. Laing
Keyword(s):  
Spinal Cord ◽  
Electrical Stimulation ◽  
Chick Embryo ◽  
Horseradish Peroxidase ◽  
Brachial Plexus ◽  
Limb Bud ◽  
Motor Innervation ◽  
Lateral Edge ◽  
Limb Innervation

Chick embryo wing buds were rotated close to the lateral edge of the somites at stage 19, prior to limb innervation. Despite the abnormal orientation of the resulting limb, the motor pools to biceps and triceps were largely normal, as judged by electrical stimulation and horseradish peroxidase labelling just prior to hatching. The only abnormalities were a few caudal motoneurons innervating biceps and a few rostral motoneurons innervating triceps. This distribution is similar to that seen normally in young embryos before the completion of motoneuron death and it is suggested that the rotation may be keeping alive motoneurons which otherwise would die. The morphology of the brachial plexus supplying rotated wings was abnormal. It is concluded that axons growing into the limb bud from the spinal cord can compensate for reversal of both the limb axes and selectively innervate appropriate muscles. The result is consistent with others in which proximal reversal of one limb axis alone produced normal innervation.

Reformation of the pattern of neuromuscular connections in the regenerated axolotl hindlimb

Development ◽  
1987 ◽  
Vol 99 (2) ◽  
pp. 221-230
Author(s):  
N. Stephens ◽  
N. Holder
Keyword(s):  
Spinal Cord ◽  
Horseradish Peroxidase ◽  
Detailed Analysis ◽  
Normal Control ◽  
Motor Neurone ◽  
Normal Position ◽  
Distal Limb ◽  
Neuronal Tracing ◽  
Limb Muscles ◽  
Motor Neurones

Retrograde neuronal tracing with horseradish peroxidase (HRP) was used to determine the position in the spinal cord of motor neurone pools innervating muscles in the regenerated axolotl hindlimb. This method allows a detailed analysis of the accuracy of reformation of neuromuscular connections. The results show that regenerated distal limb muscles are reinnervated by motor neurones in the same region of the cord as those that innervate normal control distal limb muscles but that proximal muscles are innervated by a mixture of motor neurones in a normal position and motor neurones in a region of the spinal cord that normally supplies innervation to distal limb muscles. This difference between the reinnervation of proximal and distal limb muscles suggests that axons destined for proximal muscles may not enter distal limb territory during reinnervation of the regenerated limb.

Horseradish Peroxidase Studies in Animals with Neuromuscular Transpositions

1981 ◽  
Vol 90 (4) ◽  
pp. 396-397 ◽  
Author(s):  
G. David Neal ◽  
Dwight Sutton ◽  
Gregory Duncan ◽  
Charles W. Cummings
Keyword(s):  
Spinal Cord ◽  
Horseradish Peroxidase ◽  
Motor Neurons ◽  
Cervical Spinal Cord ◽  
Retrograde Transport ◽  
Laryngeal Nerve ◽  
Nucleus Ambiguus ◽  
Axonal Connections ◽  
Motor End Plate ◽  
Posterior Cricoarytenoid

Horseradish peroxidase (hrp) is used to trace axonal connections from the motor end-plate to the driving neuron. This technique has confirmed that the neurons activating the sternothyroid muscle are located in the cervical spinal cord, while those controlling the posterior cricoarytenoid (pca) are found in the nucleus ambiguus ipsilaterally. Eight rabbits underwent a sternothyroid ansa pedicle implantation to the pca at the time of sectioning the recurrent laryngeal nerve ipsilaterally. After two months, four of these animals received hrp injections into the previously implanted pca. Brainstem staining hrp did not reveal any retrograde transport to the motor neurons that were known to control the sternothyroid. Possible reasons for the failure of retrograde transport are discussed.

Effects of Vincristine on Endothelial Microtubules in the Spinal Cord

1976 ◽  
Vol 34 ◽  
pp. 58-59
Author(s):  
John L. Beggs ◽  
John D. Waggener ◽  
Wanda Miller
Keyword(s):  
Spinal Cord ◽  
Biological Activity ◽  
Horseradish Peroxidase ◽  
Transport Mechanism ◽  
Vasogenic Edema ◽  
Vesicular Transport ◽  
Close Proximity

Microtubules (MT) are versatile organelles participating in a wide variety of biological activity. MT involvement in the movement and transport of cytoplasmic components has been well documented. In the course of our study on trauma-induced vasogenic edema in the spinal cord we have concluded that endothelial vesicles contribute to the edema process. Using horseradish peroxidase as a vascular tracer, labeled endothelial vesicles were present in all situations expected if a vesicular transport mechanism was in operation. Frequently,labeled vesicles coalesced to form channels that appeared to traverse the endothelium. The presence of MT in close proximity to labeled vesicles sugg ested that MT may play a role in vesicular activity.

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