The structure of a nervous system—Nerve fibres, cells, and ganglia.

2011 ◽  
pp. 26-54
Author(s):  
H. Charlton Bastian
Keyword(s):  
Nervous System ◽  
Nerve Fibres

Aberrant Nerve Fibres in Human Development

Development ◽  
1960 ◽  
Vol 8 (2) ◽  
pp. 119-129
Author(s):  
J. D. Boyd ◽  
A. F. W. Hughes
Keyword(s):  
Nervous System ◽  
Human Development ◽  
Nerve Fibre ◽  
Early Years ◽  
Developmental Studies ◽  
Nerve Fibres ◽  
Ground Plan ◽  
Technical Developments ◽  
Previous Decade ◽  
Ramón Y Cajal

In the early years of this century debate concerning the development of nerve fibres became more intense. During the previous decade, following the developmental studies of His (1883, 1886) and the early embryological studies of Ramon y Cajal (1890), the neurone theory as proclaimed by Waldeyer in 1891 seemed assured of victory; but when, with Apáthy and Bethe, new technical developments diverted attention from the whole neurone to its apparent constituents, the neurofibrillae, the simple concept of the outgrowth of the nerve fibre became enmeshed in complexity. Methods for their impregnation with silver were soon elaborated (Bielschowsky, 1904; Ramon y Cajal, 1903), and Held (1907) affirmed that a network of neurofibrillae preceded the appearance of the definitive nerve process. This claim became associated with the much older views of Hensen (1864, 1876) that protoplasmic strands were the forerunners of the nerve fibres and constituted a ground plan for the later development of the peripheral nervous system.

scholarly journals XIV.—On the Relation of Nerves to Odontoblasts, and on the Growth of Dentine

1892 ◽  
Vol 36 (2) ◽  
pp. 321-333 ◽  
Author(s):  
W. G. Aitchison Robertson
Keyword(s):  
Nervous System ◽  
Nerve Trunk ◽  
The Body ◽  
Osmic Acid ◽  
Nerve Fibres ◽  
Incisor Tooth ◽  
Highly Sensitive ◽  
Single Nerve ◽  
Lateral Branches ◽  
External Stimuli

Clinical and pathological observation both show that the dentine of the tooth is very closely connected with the nervous system, and is in consequence highly sensitive. Upon what structures does the sensibility of the dentine depend? In what manner is the dentine connected with the nerves of the pulp so as to become so sensitive to external stimuli?Perhaps there is no other structure in the body which is so largely supplied with nerves as the pulp of the tooth; even in the smallest fragment we find many nerve fibres. If we take the pulp from the incisor tooth of an ox and examine it after having allowed it to lie in a solution of osmic acid for a few minutes, we can see clearly through the darkened semi-transparent tissue a large blackened nerve trunk passing up the centre of the pulp, giving off on its way innumerable lateral branches, and dividing in a brush-like manner near the upper part of the pulp. All the fine branches are directed towards the periphery of the pulp. In longitudinal sections of the pulp we can see the same in greater detail; many large bundles of medullated and non-medullated nerve fibres running longitudinally near the centre and giving off lateral branches, which are found in great numbers near the periphery and divide into single nerve fibres just under the odontoblastic layer, being specially numerous at the apex of the pulp.

scholarly journals  Expression of corticotropin releasing factor (CRF) in the enteric nervous system of the jejunum of sheep

2011 ◽  
Vol 56 (No. 11) ◽  
pp. 551-560 ◽  
Author(s):  
A. Czujkowska ◽  
MB Arciszewski
Keyword(s):  
Nervous System ◽  
Smooth Muscle ◽  
Muscle Layer ◽  
Corticotropin Releasing Factor ◽  
Enteric Neurons ◽  
Nerve Fibres ◽  
Myenteric Neurons ◽  
Smooth Muscle Layer ◽  
Circular Smooth Muscle ◽  
A Minor

 Corticotropin releasing factor (CRF), a 41-amino acid neuropeptide widely distributed in the mammalian central nervous system, has been shown to influence several gastrointestinal functions. Recent studies show that CRF released locally from enteric nerves may also underlie alterations in gut function. In this study, immunohistochemisty was applied to demonstrate the presence of CRF in the jejunum of sheep. Using double immunohistochemical staining the co-localization of CRF with vasoactive intestinal peptide (VIP), galanin, tyrosine hydroxylase (TH), neuropeptide Y (NPY) and substance P (SP) was evaluated. The presence of CRF was detected in myenteric neurons (3.6 ± 0.9%) as well as in submucous neurons (10.5 ± 1.2%). In the ovine jejunum different numbers of CRF-expressing nerve fibres were detected in myenteric ganglia, submucous ganglia, circular smooth muscle layer, lamina muscularis mucosae and between mucosal glands. None of the CRF-positive enteric neurons and CRF-positive nerve fibres exhibited the presence of TH. CRF-immunoreactive (IR) myenteric neurons widely co-expressed VIP and/or NPY. A minor population of CRF-IR myenteric neurons additionally co-stored SP. Galanin was not present in CRF-IR myenteric neurons. The presence of VIP was observed in the vast majority of CRF-positive submucous neurons. Moderate numbers of CRF-IR sumbucous neurons co-expressing galanin or NPY were also found. The presence of SP in CRF-positive submucous neurons was noted only incidentally. In the circular smooth muscle layer CRF-IR/VIP-IR, CRF-IR/NPY-IR as well as CRF-IR/SP-IR nerve fibres were present. In the mucosal layer of the ovine jejunum CRF-IR nerve fibres co-stored additionally VIP, galanin, NPY or SP. This present study provides for the first time evidence that CRF present in different subclasses of enteric neurons may influence certain activities of the ovine jejunum. Co-localization studies indicate that VIP, galanin, SP and NPY functionally co-operate with CRF in the jejunum of the sheep.  

IV. Observations on the nervous system of aurelia aurita

1878 ◽  
Vol 27 (185-189) ◽  
pp. 16-17
Keyword(s):  
Nervous System ◽  
Close Contact ◽  
The Other ◽  
Ciliated Cells ◽  
Nerve Fibres ◽  
Primitive Form ◽  
Vertebrate Embryo ◽  
Limited Length ◽  
Central Nervous Structures ◽  
Epithelium Cells

The author describes the nervous system of Aurelia as consisting in addition to the lithocysts and certain tracts of specially modified epithelium in their neighbourhood, of an interlacement of nerve-fibres covering the whole of the under surface of the umbrella and lying between the ectodermal epithelium and the muscular sheet. Each nerve-fibre presents near the middle of its course a nucleated enlargement in the shape of a bipolar nerve-cell, which is thus interpolated in the course of the fibre. With regard to these nerve-fibres it is remarked-firstly, that they are of limited length, seldom exceeding four millimetres; second, that they never come into actual continuity with other fibres, although they frequently run closely parallel for a certain distance, and often form extremely intricate interlacements by the coming together of a number of fibres. The fibres occasionally branch. They are described as ending generally by finely-tapered extremities, which are in close contact with the substance of the muscular fibres, but sometimes the termination of the nerve is dilated into a flattened nucleated expansion, probably a primitive form of motorial end plate. The structure and relations of the lithocysts are then treated of. The lithocyst is described as consisting of an ectodermic covering and an endodermic core, the two being nearly everywhere separated by a thin layer of the jelly-like mesoderm. The ectodermic covering con­sists, except over the free end where the cells are simple and flattened, of long columnar, ciliated cells, the fixed ends branching into delicate fibres, which form a stratum underneath the epithelium. A similar condition of the ectoderm is described as met with in two depressions of the surface, one being situate above, and the other below, the lithocyst; and the resemblance which the elongated epithelium cells with the subjacent granular-looking, but in reality fibrous stratum, exhibits to the developing central nervous structures in the vertebrate embryo is pointed out. These parts, in fact, probably represent the first beginnings—phylogenetically—of a central nervous system. Some of the cells of the ectodermic covering of the lithocyst are pigmented, and these cells are provided each with an excessively long and fine (sensorial) filament instead of with vibratile cilia.

Branchial innervation and ciliary control in the ascidian Corella

1974 ◽  
Vol 187 (1086) ◽  
pp. 1-35 ◽  
Keyword(s):  
Nervous System ◽  
Resting Potential ◽  
Pacemaker Activity ◽  
Ciliated Cells ◽  
Nerve Fibres ◽  
Nervous Control ◽  
The Central Nervous System ◽  
Intracellular Microelectrodes ◽  
The Common ◽  
Branchial Nerve

The cilia lining the stigmata of the branchial sac of an ascidian circulate water through the animal. These stigmatal cilia are under nervous control; when either siphon is stimulated, both siphons close by muscular contractions and at the same time the stigmatal cilia stop beating simultaneously in all parts of the branchial sac. Spontaneous ciliary arrests may also occur, with or without associated closure of the siphons. Elements of the branchial nervous system that run in the gill bars are assumed to be concerned in coordination of the ciliary arrests. The majority of the branchial nerve fibres emerge dorsally from the visceral nerves that form the posterior brain roots, although nerves are also believed to enter the branchial sac along its anterior margin. No cell bodies could be found in the branchial nerves or in the visceral nerves, so that the cell bodies of the branchial nerve fibres are assumed to lie in the central nervous system. The branchial nerve fibres form a peripheral conducting net extending throughout the branchial sac. Branches of these nerve fibres terminate in contact with some of the ciliated cells; cell-to-cell conduction (through close junctions?) probably spreads excitation to the other ciliated cells. Nerve-nerve junctions appear to be more sensitive to curare than those between nerves and ciliated cells. Electrical recordings from the branchial sac, obtained with suction electrodes, show that arrest of the cilia is accompanied by electrical activity, and that prolonged arrest is maintained by trains of regular pulses. Intracellular microelectrodes in the ciliated cells indicate that these cells have a negative resting potential of 30-40 mV, and that a ciliary arrest is associated with a positive-going spike of 45-50 mV. The externally recorded ‘ciliary arrest potentials’ probably represent the coordinated depolarization of many ciliated cells. The rhythmical character of the trains of pulses presumably depends on pacemaker activity; this is not localized, since intact organisms or isolated small portions of the branchial sac are capable of generating similar trains of pulses. During the arrest response the stigmatal cilia first perform a reverse beat, then maintain the reverse position for several seconds before slowly relaxing and after several more seconds recommencing to beat with progressively increasing amplitude. The duration of the arrest response varies in media with different concentrations of the common cations, and also varies in response to repetitive stimulation, in a manner which suggests that the depolarization of the ciliated cells is associated with an influx of Ca 2+ , so that the ciliary control here may have some close parallels with that described for Paramecium .

The nervous system of a pilidium larva: evidence from electron microscope reconstructions

1985 ◽  
Vol 63 (8) ◽  
pp. 1909-1916 ◽  
Author(s):  
T. C. Lacalli ◽  
J. E. West
Keyword(s):  
Nervous System ◽  
Electron Microscope ◽  
Similar Type ◽  
Ciliary Band ◽  
Nerve Fibres ◽  
Larval Nervous System ◽  
Marginal Band ◽  
Friday Harbor ◽  
And Behavior ◽  
First Time

The principal ultrastructural features of a pilidium larva from Friday Harbor (pilidium A, unidentified as to species) are summarized and, based on electron microscope reconstructions, the larval nervous system is described for the first time. Ciliary effectors in the larva include the marginal ciliary band, which is drawn out to form a small accessory ridge at each of the junctions between lobes, and a pair of suboral (buccal) ridges, one on either side of the stomodeum, that run between the mouth and marginal band. The nervous system consists of a small intratrochal nerve supplying the marginal band, an oral nerve that encircles the mouth at the junction of stomodeum and stomach, and a pair of nerves connecting these that run beneath the suboral ridges. The nerve fibres appear to arise from uniciliate cells in the marginal band and the suboral region. The organization, innervation, and behavior of pilidium A are discussed briefly with reference to Müller's larva, a related larva with a similar type of trochal innervation.

Immunocytochemical demonstration of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica (Trematoda, Digenea)

Parasitology ◽  
1989 ◽  
Vol 98 (2) ◽  
pp. 227-238 ◽  
Author(s):  
R. M. Magee ◽  
I. Fairweather ◽  
C. F. Johnston ◽  
D. W. Halton ◽  
C. Shaw
Keyword(s):  
Nervous System ◽  
Egg Production ◽  
Liver Fluke ◽  
Fasciola Hepatica ◽  
Adult Fluke ◽  
Nerve Fibres ◽  
Indirect Immunofluorescence Technique ◽  
The Central Nervous System ◽  
Positive Immunoreactivity ◽  
Longitudinal Nerve

SUMMARYThe localization and distribution of neuropeptides in the nervous system of the liver fluke, Fasciola hepatica at different stages in the development of the adult fluke have been determined by an indirect immunofluorescence technique, using antisera to 19 vertebrate peptides and the invertebrate neuropeptide, FMRFamide. Positive immunoreactivity was obtained with antisera to pancreatic polypeptide (PP), peptide tyrosine tyrosine (PYY), substance P (SP) and FMRFamide. Cell bodies and nerve fibres immunoreactive to the 4 peptides are present in the anterior ganglia and the 3 pairs of longitudinal nerve cords and their commissures in the central nervous system. In the peripheral nervous system, immunoreactivity occurs in the nerve plexuses supplying the subtegumental musculature, the oral and ventral suckers, and the muscular lining of the male and female reproductive ducts, including the ootype, uterus, cirrus pouch and gonopore. Cells displaying immunoreactivity to PYY and FMRFamide lie amongst the Mehlis' gland cells that surround the ootype. Processes from these cells extend into the wall of the ootype. One group of PP-immunoreactive cells occurs at the junction of the vitelline and ovovitelline ducts, whilst another group is situated at the entrance to the uterus from the ootype. The results are discussed in relation to the possible roles of the peptides in the neurophysiology and egg production of the fluke.

scholarly journals Further Observations on the Effect of De-Afferentation on the Locomotory Activity of Amphibian Limbs

1946 ◽  
Vol 23 (2) ◽  
pp. 121-132
Author(s):  
J. GRAY ◽  
H. W. LISSMANN
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Motor Nerve ◽  
Sensory Nerve ◽  
The Body ◽  
Locomotory Activity ◽  
Nerve Supply ◽  
Nerve Fibres ◽  
Stimulation Of ◽  
Intact Limb

1. An examination of a large number of toads has confirmed the conclusion that unilateral integrity of the sensory and motor nerve supply to one segment is necessary for the maintenance of the normal diagonal pattern of ambulation. The site of the intact segment is immaterial; segments of the body are equally effective as those of a limb provided the number of sensory nerve fibres is approximately the same. 2. If three limbs and the body are de-afferentated, a stimulus applied to the fourth intact limb can evoke well co-ordinated ambulation in all four limbs. If the motor roots of the fourth limb are cut, a stimulus applied to this limb invariably elicits only a monophasic response in each of the remaining three limbs. The nature of the monophasic response is always such as tends to move the body away from the source of stimulation. 3. A central nervous system totally isolated from stimulation of proprioceptor or labyrinthine origin cannot sustain co-ordinated movements of a toad either on land or in water.

The Effects of Curare in the Cockroach

1970 ◽  
Vol 52 (3) ◽  
pp. 583-592
Author(s):  
K. J. FRIEDMAN ◽  
A. D. CARLSON
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Motor Nerve ◽  
Nerve Fibres ◽  
Affected Area ◽  
Metathoracic Ganglion ◽  
The Central Nervous System ◽  
Mechanical Studies

1. The nature of insect curarization has been investigated in the cockroach, P. americana. Mechanical studies of leg contraction revealed that dTC, whether injected into the abdomen, injected into a leg or applied to the metathoracic ganglion, produces failure of contraction. 2. The contraction failure caused by injecting dTC into a leg or by applying dTC to the metathoracic ganglion could be reversed by washing the drug out of the affected area. 3. The central nervous system does not appear to be essential for curare-induced contraction failure. The contraction of metathoracic legs deprived of their metathoracic ganglion is abolished in the presence of curare. 4. Since curare produces contraction failure when applied to the metathorax and when injected into a leg, the site of curare action must be present in both these locations. The motor nerve fibres are present in both these locations and it is proposed that contraction failure is due to the action of curare on these fibres.

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