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.

Selective bilateral motor innervation in Xenopus tadpoles with one hind limb

Development ◽  
1981 ◽  
Vol 65 (1) ◽  
pp. 149-163
Author(s):  
Alan H. Lamb
Keyword(s):  
Horseradish Peroxidase ◽  
Hind Limb ◽  
Limb Bud ◽  
The Other ◽  
Motor Innervation ◽  
Two Sides

Bilateral innervation of a single hindlimb bud was induced by amputating the other limb bud and disrupting the barriers between the two sides. Though the routes of the crossed nerves were necessarily abnormal, the motor projections that developed subsequently were normal as determined by horseradish peroxidase tracing. The limb therefore appears to be innervated selectively, each region being invaded and/or synapsed with only by motoneurones at particular locations. The numbers of motoneurones surviving after metamorphosis were almost normal on both sides provided the operation was done before motor invasion of the limb bud begins. From this it is argued that the axons were probably guided actively to their correct destinations. Without such guidance, axons would probably not have been able to find their correct termination sites and motoneurone survival would therefore have been depressed. The normal motoneurone numbers also imply that the single limb was supporting twice its usual quota of motoneurones. The hypothesis that motoneurones compete in the limb for survival is therefore not supported.

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.

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.

Cardiovascular and Metabolic Responses to Electrical Stimulation-Induced Leg Exercise in Spinal Cord Injury

1997 ◽  
Vol 36 (04/05) ◽  
pp. 372-375 ◽  
Author(s):  
J. R. Sutton ◽  
A. J. Thomas ◽  
G. M. Davis
Keyword(s):  
Spinal Cord ◽  
Heart Rate ◽  
Spinal Cord Injury ◽  
Cardiac Output ◽  
Electrical Stimulation ◽  
Knee Flexion ◽  
Flexion Extension ◽  
Cord Injury ◽  
Leg Exercise ◽  
Leg Muscle

Abstract:Electrical stimulation-induced leg muscle contractions provide a useful model for examining the role of leg muscle neural afferents during low-intensity exercise in persons with spinal cord-injury and their able-bodied cohorts. Eight persons with paraplegia (SCI) and 8 non-disabled subjects (CONTROL) performed passive knee flexion/extension (PAS), electrical stimulation-induced knee flexion/extension (ES) and voluntary knee flexion/extension (VOL) on an isokinetic dynamometer. In CONTROLS, exercise heart rate was significantly increased during ES (94 ± 6 bpm) and VOL (85 ± 4 bpm) over PAS (69 ± 4 bpm), but no changes were observed in SCI individuals. Stroke volume was significantly augmented in SCI during ES (59 ± 5 ml) compared to PAS (46 ± 4 ml). The results of this study suggest that, in able-bodied humans, Group III and IV leg muscle afferents contribute to increased cardiac output during exercise primarily via augmented heart rate. In contrast, SCI achieve raised cardiac output during ES leg exercise via increased venous return in the absence of any change in heart rate.

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