Sensory nerve routes in chick wing buds deprived of motor innervation

Development ◽  
1986 ◽  
Vol 95 (1) ◽  
pp. 37-52
Author(s):  
Gavin J. Swanson ◽  
Julian Lewis
Keyword(s):  
Peripheral Nerve ◽  
Neural Tube ◽  
Sensory Nerve ◽  
Embryonic Chick ◽  
Motor Axons ◽  
Motor Innervation ◽  
Nerve Fibres ◽  
Sensory Axons ◽  
Muscle Nerve ◽  
Focused Beam

To what extent do motor and sensory nerve fibres depend on one another for guidance during the development of peripheral nerve patterns? This question has been examined by looking at the paths taken by sensory nerve fibres growing into the embryonic chick wing in the absence of motor axons. The precursors of the motoneurones were destroyed by irradiating the appropriate part of the neural tube with a focused beam of ultraviolet light, before axons had grown out. The limb nerve patterns seen 5 to 7 days later revealed that sensory fibres followed the usual paths of main nerve trunks and formed cutaneous nerve branches in an almost normal way. However, the sensory fibres did not take the paths where muscle nerve branches are normally seen. Apparently, sensory axons for the most part do not depend on motor axons for guidance, except in the case of proprioceptive fibres, which require guidance from motor axons over the final steps of their path into muscle.

Selective Reinnervation of Regenerating Mixed Nerve Fibres Across a Silicone Tube Gap

1996 ◽  
Vol 21 (5) ◽  
pp. 660-663 ◽  
Author(s):  
Z-J. LUO ◽  
S-B. LU
Keyword(s):  
Dorsal Root ◽  
Tibial Nerve ◽  
Motor Nerve ◽  
Sensory Nerve ◽  
Nerve Fibres ◽  
Silicone Tube ◽  
Spinal Dorsal ◽  
Sensory Axons ◽  
Target Organs ◽  
Mixed Nerve

This study investigated specific regeneration of a mixed motor and sensory nerve by the method of spinal dorsal root ganglions resection. A 10 mm segment of tibial nerve was resected and the nerve ends inserted in a silicone tube. Fourteen weeks later, dorsal root ganglia from L6 to S1 were resected on the experiment side. Twenty weeks later, the regenerating motor nerve fibres of mixed nerves selectively grew into motor branches. The rate of misdirected growth in mixed nerves was less than 6%. These results suggest that regenerating motor and sensory axons of mixed nerves are able to select their distal target organs accurately. Better results may be obtained using the entubulation repair method.

Atypical Spindles in Reinnervated Rat Muscles

Development ◽  
1961 ◽  
Vol 9 (3) ◽  
pp. 456-467
Author(s):  
P. Hník ◽  
J. Zelená
Keyword(s):  
Peripheral Nerve ◽  
Functional Groups ◽  
Transition Period ◽  
Present Report ◽  
Sensory Nerve ◽  
Morphological Characteristics ◽  
Muscle Spindles ◽  
Nerve Fibres ◽  
Muscle Receptors ◽  
Short Transition

In young rats, following lesions of a peripheral nerve at birth, immature muscle spindles disintegrate during a short transition period (Zelená, 1957), and even after several months of reinnervation the reinnervated muscles are usually found to contain no spindles (Zelená & Hník, 1960). Nevertheless, occasional small spindles of atypical structure are observed in some of these muscles. In the present report, the structure and morphological characteristics of these atypical spindles were studied and compared with normal spindles. Since differences in fast and slow muscles may include differences in muscle receptors (Voss, 1937; Maruseva, 1947; Hagbarth & Wohlfahrt, 1952; Freimann, 1953; Cooper, 1960), the number, size, and distribution of spindles were studied in two muscles representing the two functional groups. The origin of atypical spindles in the reinnervated muscles is not clear. These spindles could either differentiate anew under the influence of regenerating sensory nerve fibres, or they could originate from spindles reinnervated before their ultimate disintegration had taken place.

Paths taken by sensory nerve fibres in aneural chick wing buds

Development ◽  
1985 ◽  
Vol 86 (1) ◽  
pp. 109-124
Author(s):  
Gavin J. Swanson
Keyword(s):  
Peripheral Nerve ◽  
Nerve Fibre ◽  
Sensory Nerve ◽  
Axon Outgrowth ◽  
Sensory Ganglia ◽  
Chick Embryos ◽  
Nerve Fibres ◽  
Embryo Chick ◽  
Wing Bud ◽  
Host Embryo

What constrains growing nerves to follow the paths they take during the development of peripheral nerve patterns? This paper examines two, related, topics concerning the pathways taken by sensory nerve fibres in the embryo chick wing: the constraints imposed on the nerves by limb tissues; and the timing of axon outgrowth. Sensory ganglia from 7-day-old chick embryos were grafted into younger host embryo wing buds which had been previously denervated. The resultant nerve patterns revealed that, first, nerve fibres could grow almost anywhere within the wing bud, with the exceptions of cartilage and a region just beneath the growing tip. Secondly, the younger the host wing bud at the time of grafting, the more likely the neurites were to form a thick fascicle which followed the limb's normal nerve pathways. The wing apparently does not impose a rigid restraint on nerves to grow only along certain routes; however, if a nerve fibre reaches a normal nerve pathway, it prefers to follow it.

scholarly journals Axon typing of rat muscle nerves using a double staining procedure for cholinesterase and carbonic anhydrase.

1991 ◽  
Vol 39 (12) ◽  
pp. 1617-1625 ◽  
Author(s):  
M J Szabolcs ◽  
A Windisch ◽  
R Koller ◽  
M Pensch
Keyword(s):  
Carbonic Anhydrase ◽  
Cross Sections ◽  
Sensory Nerve ◽  
Histological Section ◽  
Trapezius Muscle ◽  
Motor Units ◽  
Conventional Technique ◽  
Nerve Fibers ◽  
Staining Procedure ◽  
Muscle Nerve

We developed a method for detecting activity of axonal cholinesterase (CE) and carbonic anhydrase (CA)--markers for motor and sensory nerve fibers (NFs)--in the same histological section. To reach this goal, cross-sections of muscle nerves were sequentially incubated with the standard protocols for CE and CA histochemistry. A modified incubation medium was used for CA in which Co++ is replaced by Ni++. This avoids interference of the two histochemical reactions because Co++ binds unspecifically to the brown copper-ferroferricyanide complex representing CE activity, whereas Ni++ does not. Cross-sections of the trapezius muscle nerve containing efferent and afferent NFs in segregated fascicles showed that CE activity was confined to motor NFs. Axonal CA was detected solely in sensory NFs. The number of labeled motor and sensory NFs determined in serial cross-sections stained with either the new or the conventional technique was not significantly different. Morphometric analysis revealed that small unreactive NFs (diameter less than 5 microns) are afferent, medium-sized ones (5 microns less than d less than 7 microns) are unclassifiable, and large ones (d greater than 7 microns) are efferent. The heterogenous CE activity of thick (alpha) motor NFs is linked to the type of their motor units. "Fast" motor units contain CE reactive NFs; "slow" ones have CE negative neurites.

Conduction Velocities and Their Temperature Coefficients in Sensory Nerve Fibres of Cockroach Legs

1967 ◽  
Vol 46 (1) ◽  
pp. 63-84
Author(s):  
K. M. CHAPMAN ◽  
J. H. PANKHURST
Keyword(s):  
Conduction Velocity ◽  
Periplaneta Americana ◽  
Sensory Nerve ◽  
Point Of View ◽  
Conduction Delay ◽  
Nerve Fibres ◽  
Impulse Frequency ◽  
Temperature Coefficients ◽  
Conduction Velocities ◽  
Sensory Encoding

1. Conduction velocities of individual afferent nerve fibres from tactile spines and proprioceptive campaniform sensilla have been measured in situ over the temperature range 5-42° C., in leg preparations of the cockroach Periplaneta americana. 2. Conduction velocities at 20° C. (u20) averaged 3.3±1.4 m./sec., ranging from 1.6 to 11.0 m./sec. 3. Temperature coefficients, expressed as Q10 for the interval 20-30° C., averaged 1.7±0.24, ranging from 1.3 to 2.6. 4. The length of the propagated disturbance is about 2-3 mm., and is nearly temperature-independent. 5. Fibre diameters, estimated from conduction velocity, must be about 10 µ. 6. There is no correlation between conduction velocity and distance from the sensillum to the thoracic ganglion. Conduction delays in fibres conducting within one standard deviation of mean u20 range from about 2 to 15 msec., from the most proximal to the most distal tactile spines. 7. The effect of conduction delay on temporal and spatial sensory encoding is probably unimportant from a behavioural point of view. It contributes a factor of the form exp(-sd/u) to the sensory transfer function, and may be appreciable at upper physiological frequencies of impulse frequency modulation.

scholarly journals Fast-spiking GABA circuit dynamics in the auditory cortex predict recovery of sensory processing following peripheral nerve damage

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Jennifer Resnik ◽  
Daniel B Polley
Keyword(s):  
Peripheral Nerve ◽  
Auditory Cortex ◽  
Sensory Processing ◽  
Cortical Neurons ◽  
Sensory Nerve ◽  
Intracortical Inhibition ◽  
Nerve Fibers ◽  
Nerve Damage ◽  
Inhibitory Neurons ◽  
Sound Processing

Cortical neurons remap their receptive fields and rescale sensitivity to spared peripheral inputs following sensory nerve damage. To address how these plasticity processes are coordinated over the course of functional recovery, we tracked receptive field reorganization, spontaneous activity, and response gain from individual principal neurons in the adult mouse auditory cortex over a 50-day period surrounding either moderate or massive auditory nerve damage. We related the day-by-day recovery of sound processing to dynamic changes in the strength of intracortical inhibition from parvalbumin-expressing (PV) inhibitory neurons. Whereas the status of brainstem-evoked potentials did not predict the recovery of sensory responses to surviving nerve fibers, homeostatic adjustments in PV-mediated inhibition during the first days following injury could predict the eventual recovery of cortical sound processing weeks later. These findings underscore the potential importance of self-regulated inhibitory dynamics for the restoration of sensory processing in excitatory neurons following peripheral nerve injuries.

scholarly journals Hyperpolarization-activated cyclic-nucleotide-gated channels potentially modulate axonal excitability at different thresholds

2017 ◽  
Vol 118 (6) ◽  
pp. 3044-3050 ◽  
Author(s):  
Dinushi Weerasinghe ◽  
Parvathi Menon ◽  
Steve Vucic
Keyword(s):  
Cyclic Nucleotide ◽  
Neurological Diseases ◽  
Lower Threshold ◽  
Resting Membrane Potential ◽  
Hcn Channels ◽  
Motor Axons ◽  
Cyclic Nucleotide Gated Channels ◽  
Sensory Axons ◽  
Current Threshold ◽  
Axonal Excitability

Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels mediate differences in sensory and motor axonal excitability at different thresholds in animal models. Importantly, HCN channels are responsible for voltage-gated inward rectifying ( Ih) currents activated during hyperpolarization. The Ih currents exert a crucial role in determining the resting membrane potential and have been implicated in a variety of neurological disorders, including neuropathic pain. In humans, differences in biophysical properties of motor and sensory axons at different thresholds remain to be elucidated and could provide crucial pathophysiological insights in peripheral neurological diseases. Consequently, the aim of this study was to characterize sensory and motor axonal function at different threshold. Median nerve motor and sensory axonal excitability studies were undertaken in 15 healthy subjects (45 studies in total). Tracking targets were set to 20, 40, and 60% of maximum for sensory and motor axons. Hyperpolarizing threshold electrotonus (TEh) at 90–100 ms was significantly increased in lower threshold sensory axons times ( F = 11.195, P < 0.001). In motor axons, the hyperpolarizing current/threshold ( I/ V) gradient was significantly increased in lower threshold axons ( F = 3.191, P < 0.05). The minimum I/ V gradient was increased in lower threshold motor and sensory axons. In conclusion, variation in the kinetics of HCN isoforms could account for the findings in motor and sensory axons. Importantly, assessing the function of HCN channels in sensory and motor axons of different thresholds may provide insights into the pathophysiological processes underlying peripheral neurological diseases in humans, particularly focusing on the role of HCN channels with the potential of identifying novel treatment targets. NEW & NOTEWORTHY Hyperpolarization-activated cyclic-nucleotide-gated (HCN) channels, which underlie inward rectifying currents ( Ih), appear to mediate differences in sensory and motor axonal properties. Inward rectifying currents are increased in lower threshold motor and sensory axons, although different HCN channel isoforms appear to underlie these changes. While faster activating HCN channels seem to underlie Ih changes in sensory axons, slower activating HCN isoforms appear to be mediating the differences in Ih conductances in motor axons of different thresholds. The differences in HCN gating properties could explain the predilection for dysfunction of sensory and motor axons in specific neurological diseases.

The Staining of Nervous Elements by the Bodian Method

1962 ◽  
Vol s3-103 (63) ◽  
pp. 297-310
Author(s):  
TERRY WILLIAMS
Keyword(s):  
Smooth Muscle ◽  
Paraffin Sections ◽  
Nerve Fibres ◽  
End Point ◽  
Pilot Trials ◽  
Initial Ph ◽  
Muscle Nerve ◽  
Impregnation Time ◽  
Time Required

In paraffin sections of tissues containing much smooth muscle, nerve-fibres are difficult to demonstrate by silver techniques. In pilot trials Bodian's activated protargol technique proved most promising for stomach sections. From a fixed Bodian-type schedule, the effects of variation in pH, time, and temperature of impregnation were studied separately and together. These experiments provided means of determining optimal levels for some of the variables in the process. The impregnation time required for optimal staining varies according to the temperature and initial pH. Stirring, or agitation of the slides, at intervals of a few hours has been found to be a valuable aid to even staining, and if this has been done it is possible to use the stage of clearing of the fluid as an end-point indicator.

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