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.

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.

TENS equipment, techniques, and biophysical principles

2014 ◽  
Keyword(s):  
Clinical Practice ◽  
Peripheral Nerve ◽  
Nerve Fibre ◽  
Electrical Current ◽  
Electrical Characteristics ◽  
Nerve Fibres ◽  
Electrical Currents ◽  
Nerve Impulses ◽  
Different Types ◽  
Nociceptive Information

The purpose of the electrical current delivered during TENS is to generate nerve impulses in peripheral nerve fibres to modulate the flow of nociceptive information and reduce pain. The characteristics of the electrical currents (i.e. stimulating parameters) and physiology at the electrode–skin interface will influence which nerve fibres are excited. Conventional TENS and acupuncture-like TENS are two techniques developed to stimulate different types of nerve fibres. The purpose of this chapter is to overview the biophysical principles of TENS and to explain how these principles have been used to inform clinical practice by covering TENS equipment and the standard TENS device, the electrical characteristics of currents produced by a standard TENS device, lead wires and electrodes, the physiology at the electrode–skin interface including nerve fibre activation by TENS, and TENS techniques used in clinical practice, including conventional TENS and acupuncture-like TENS (AL-TENS).

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.

scholarly journals Early Detection of Diabetic Peripheral Neuropathy: A Focus on Small Nerve Fibres

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 165
Author(s):  
Jamie Burgess ◽  
Bernhard Frank ◽  
Andrew Marshall ◽  
Rashaad S. Khalil ◽  
Georgios Ponirakis ◽  
...  
Keyword(s):  
Peripheral Neuropathy ◽  
Nerve Fibre ◽  
Diabetic Peripheral Neuropathy ◽  
Point Of Care ◽  
Unmet Need ◽  
Screening Tools ◽  
Nerve Fibres ◽  
Diagnostic Laboratory ◽  
Corneal Confocal Microscopy ◽  
Small Nerve

Diabetic peripheral neuropathy (DPN) is the most common complication of both type 1 and 2 diabetes. As a result, neuropathic pain, diabetic foot ulcers and lower-limb amputations impact drastically on quality of life, contributing to the individual, societal, financial and healthcare burden of diabetes. DPN is diagnosed at a late, often pre-ulcerative stage due to a lack of early systematic screening and the endorsement of monofilament testing which identifies advanced neuropathy only. Compared to the success of the diabetic eye and kidney screening programmes there is clearly an unmet need for an objective reliable biomarker for the detection of early DPN. This article critically appraises research and clinical methods for the diagnosis or screening of early DPN. In brief, functional measures are subjective and are difficult to implement due to technical complexity. Moreover, skin biopsy is invasive, expensive and lacks diagnostic laboratory capacity. Indeed, point-of-care nerve conduction tests are convenient and easy to implement however questions are raised regarding their suitability for use in screening due to the lack of small nerve fibre evaluation. Corneal confocal microscopy (CCM) is a rapid, non-invasive, and reproducible technique to quantify small nerve fibre damage and repair which can be conducted alongside retinopathy screening. CCM identifies early sub-clinical DPN, predicts the development and allows staging of DPN severity. Automated quantification of CCM with AI has enabled enhanced unbiased quantification of small nerve fibres and potentially early diagnosis of DPN. Improved screening tools will prevent and reduce the burden of foot ulceration and amputations with the primary aim of reducing the prevalence of this common microvascular complication.

Neural induction and regionalisation in the chick embryo

Development ◽  
1992 ◽  
Vol 114 (3) ◽  
pp. 729-741 ◽  
Author(s):  
K.G. Storey ◽  
J.M. Crossley ◽  
E.M. De Robertis ◽  
W.E. Norris ◽  
C.D. Stern
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Molecular Markers ◽  
Chick Embryo ◽  
Normal Development ◽  
Neural Induction ◽  
Stage 4 ◽  
Embryo Chick ◽  
Host Embryo ◽  
Embryonic Region

Induction and regionalisation of the chick nervous system were investigated by transplanting Hensen's node into the extra-embryonic region (area opaca margin) of a host embryo. Chick/quail chimaeras were used to determine the contributions of host and donor tissue to the supernumerary axis, and three molecular markers, Engrailed, neurofilaments (antibody 3A10) and XlHbox1/Hox3.3 were used to aid the identification of particular regions of the ectopic axis. We find that the age of the node determines the regions of the nervous system that form: young nodes (stages 2–4) induced both anterior and posterior nervous system, while older nodes (stages 5–6) have reduced inducing ability and generate only posterior nervous system. By varying the age of the host embryo, we show that the competence of the epiblast to respond to neural induction declines after stage 4. We conclude that during normal development, the initial steps of neural induction take place before stage 4 and that anteroposterior regionalisation of the nervous system may be a later process, perhaps associated with the differentiating notochord. We also speculate that the mechanisms responsible for induction of head CNS differ from those that generate the spinal cord: the trunk CNS could arise by homeogenetic induction by anterior CNS or by elongation of neural primordia that are induced very early.

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.

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