scholarly journals Fused neurons and synaptic contacts in the giant nerve fibres of cephalopods

1939 ◽  
Vol 229 (564) ◽  
pp. 465-503 ◽  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Giant Cells ◽  
Nerve Cells ◽  
The Body ◽  
Complete Fusion ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
The Central Nervous System ◽  
Giant Fibre System

The fact that there are two very large nerve cells in the central nervous system of the squid, Loligo , was discovered by Williams (1909), who also gave a brief description of their connexions. His account appears never to have been amplified, or indeed even mentioned, by any subsequent worker until these enormous nerve fibres were accidentally rediscovered in 1933 (see Young 1935 a , 1936 a, b, c ). Williams considered that the whole giant-fibre system on each side of the body consists of the processes of one of the two main giant cells. In fact the arrangement is much more complicated than this, and contains two curiously opposite features of the greatest interest for the neurologist (Young 1936 £). First, the processes of the two main giant cells provide a clear case of the complete fusion of the axons of two nerve cells, thus infringing the strict canon of the neuron theory. Nevertheless, and this is the second point, there are also present, elsewhere in the system, discontinuous synapses which are perhaps more clear and easy to study than any yet described.

The Giant Nerve-Fibres in the Central Nervous System of Myxicola (Polychaeta, Sabellidae)

1948 ◽  
Vol s3-89 (5) ◽  
pp. 1-45
Author(s):  
J.A. C. NICOL
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Size Structure ◽  
Nerve Cells ◽  
The Body ◽  
Usual Sense ◽  
Fibrous Sheath ◽  
Giant Fibre ◽  
The Central Nervous System

1. A description is given of the main features of the central nervous system of Myxicola infundibulum Rénier. 2. The nerve-cord is double in the first four thoracic segments and single posteriorly. It shows segmental swellings but is not ganglionated in the usual sense in that nerve-cell accumulations are not related directly to such swellings of the cord. 3. A very large axon lies within the dorsal portion of the nerve-cord and extends from the supra-oesophageal ganglia to the posterior end of the animal. It is small in the head ganglia where it passes transversely across the mid-line, increases in diameter in the oesophageal connectives, and expands to very large size, up to 1 mm., in the posterior thorax and anterior abdomen, and gradually tapers off to about 100µ in the posterior body. It shows segmental swellings corresponding to those of the nerve-cord in each segment. It occupies about 27 per cent, of the volume of the central nervous system and 0.3 per cent, of the volume of the animal. The diameter of the fibre increases during contraction of the worm. 4. The giant fibre is a continuous structure throughout its length, without internal dividing membranes or septa. Usually a branch of the giant fibre lies in each half of the nerve-cord in the anterior thoracic segments and these several branches are continuous with one another longitudinally and transversely. 5. The giant fibre is connected with nerve-cells along its entire course; it arises from a pair of cells in the supra-oesophageal ganglia, and receives the processes of many nerve-cells in each segment. There is no difference between the nerve-cells of the giant fibre and the other nerve-cells of the cord. 6. A distinct fibrous sheath invests the giant fibre. A slight concentration of lipoid can be revealed in this sheath by the use of Sudan black. 7. About eight peripheral branches arise from the giant fibre in each segment. They have a complex course in the nerve-cord where they anastomose with one another and receive the processes of nerve-cells. Peripherally, they are distributed to the longitudinal musculature. 8. Specimens surviving 16 days following section of the nerve-cord in the thorax have shown that the giant fibre does not degenerate in front of or behind a cut, thus confirming that it is a multicellular structure connected to nerve-cells in the thorax and abdomen. 9. It is concluded that the giant fibre of M. infundibulum is a large syncytial structure, extending throughout the entire central nervous system and the body-wall of the animal. 10. The giant fibre system of M. aesthetica resembles that of M. infundibulum. 11. Some implications of the possession of such a giant axon are discussed. It is suggested that its size, structure, and simplicity lead to rapid conduction and thus effect a considerable saving of reaction time, of considerable value to the species when considered in the light of the quick contraction which it mediates. The adoption of a sedentary mode of existence has permitted this portion of the central nervous system to become developed at the expense of other elements concerned with errant habits.

scholarly journals The giant myelinated nerve fibres of the prawn

1942 ◽  
Vol 231 (582) ◽  
pp. 293-311 ◽  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Myelin Sheath ◽  
Single Cells ◽  
Myelinated Fibre ◽  
Complete Fusion ◽  
Giant Fibre ◽  
The Central Nervous System ◽  
Giant Fibres ◽  
Myelinated Fibres

Evidence is given that the median and lateral longitudinal giant myelinated fibres in the central nervous system of the prawn Leander serratus are syncitial structures, each formed by the fusion of the processes of many segmental nerve cells. Septa are found at intervals in the axoplasm of the median fibres, but they never completely transect it. They are probably relics of a condition similar to that in the earthworm where the giant fibre running the length of the cord is formed of a chain of segmental syncitial axons each divided from its neighbour by a complete septum which presumably functions as a synapse. The motor giant fibres, which are segmental and pass out of the central nervous system to the muscles, are the processes of single cells: the axoplasms of the two fibres of the pair in each segment undergo complete fusion with each other and then redivision before leaving the central nervous system. These motor giant fibres are non-myelinated within the central nervous system, although as great in diameter as other heavily myelinated fibres. They are myelinated outside the central nervous system. In the prawn therefore myelin sheath thickness is not an invariable function of axon diameter. The lateral giant-fibre synapses show complete axoplasmic discontinuity and their structure does not support Johnson’s creation of a new category of synaptic relations. Two types of synapses between fibres are described. In the first, found in the lateral giant-fibre chain, two myelinated fibres lie closely side by side for a considerable distance, but their neuroplasms are separated by a myelin layer except over an extent of less than 10 μ . In the second type, found at the point of contact of both the median and lateral fibres with the motor fibres, a myelinated fibre has synaptic connexions with a large non-myelinated fibre through many fine axonic processes which pass out through a small gap in the myelin sheath.

scholarly journals Brain-derived neurotrophic factor as a potential therapeutic tool in the treatment of nervous system disorders

2020 ◽  
Vol 74 ◽  
pp. 517-531
Author(s):  
Wioletta Kazana ◽  
Agnieszka Zabłocka
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Neurotrophic Factor ◽  
Intracellular Transport ◽  
Brain Derived Neurotrophic Factor ◽  
Nerve Cells ◽  
The Body ◽  
Bdnf Level ◽  
The Central Nervous System ◽  
The Brain

Brain-derived neurotrophic factor (BDNF) plays an important role in the proper functioning of the nervous system. It regulates the growth and survival of nerve cells, and is crucial in processes related to the memory, learning and synaptic plasticity. Abnormalities related to the distribution and secretion of BDNF protein accompany many diseases of the nervous system, in the course of which a significant decrease in BDNF level in the brain is observed. Impairments of BDNF transport may occur, for example, in the event of a single nucleotide polymorphism in the Bdnf (Val66Met) coding gene or due to the dysfunctions of the proteins involved in intracellular transport, such as huntingtin (HTT), huntingtin-associated protein 1 (HAP1), carboxypeptidase E (CPE) or sortilin 1 (SORT1). One of the therapeutic goals in the treatment of diseases of the central nervous system may be the regulation of expression and secretion of BDNF protein by nerve cells. Potential therapeutic strategies are based on direct injection of the protein into the specific region of the brain, the use of viral vectors expressing the Bdnf gene, transplantation of BDNF-producing cells, the use of substances of natural origin that stimulate the cells of the central nervous system for BDNF production, or the use of molecules activating the main receptor for BDNF – tyrosine receptor kinase B (TrkB). In addition, an appropriate lifestyle that promotes physical activity helps to increase BDNF level in the body. This paper summarizes the current knowledge about the biological role of BDNF protein and proteins involved in intracellular transport of this neurotrophin. Moreover, it presents contemporary research trends to develop therapeutic methods, leading to an increase in the level of BDNF protein in the brain.

Synaptic Relations in the Atrial Nervous System of Amphioxus

1958 ◽  
Vol s3-99 (46) ◽  
pp. 243-261
Author(s):  
QUENTIN BONE
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Peripheral Nerve ◽  
Dorsal Root ◽  
Nerve Cells ◽  
Nerve Fibres ◽  
Nerve Bundles ◽  
Analogous Manner ◽  
The Central Nervous System ◽  
Dorsal Nerve

A detailed description of the system of peripheral nerve-cells upon the gut and diverticulum of amphioxus (Branchiostoma) is given; it is shown experimentally by means of degeneration experiments that these cells are connected with the central nervous system by their own axons, which run in the dorsal-root nerves. The form and connexion of the cells are described, special attention is paid to the problems of the multinucleate cells in the plexus, and to the occurrence of possible asynaptic connexion between neighbouring nerve-cells. No sheath-cells have been observed upon the peripheral nerve-fibres, either within the atrial plexus or upon the dorsal-root nerve bundles; earlier misinterpretations of the nuclei of the cells of the epineurium around the dorsal nerve bundles are discussed. The origin of the atrial system in ontogeny is discussed; it is suggested that it arises in an analogous manner to the enteric plexuses of vertebrates, by outgrowth from the central nervous system. The part that this system of nerve-cells plays in the life of the animal is not known. Finally, the relation of this system of cells to that found upon the guts of other groups of animals is discussed, and it is concluded that the system is not homologous with the enteric systems of nerve-cells in the vertebrates.

scholarly journals III. Contributions to the anatomy of the central nervous system in vertebrate animals. Part I. Ichthyopsida. Section 1. Pisces. Subsection 1. Teleostei

1878 ◽  
Vol 27 (185-189) ◽  
pp. 415-417
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Olfactory Nerve ◽  
Nerve Cells ◽  
Mugil Cephalus ◽  
Small Cells ◽  
Nerve Fibres ◽  
The Central Nervous System ◽  
Anterior Pair ◽  
The Brain

The brain of Mugil cephalus consists of three pairs and one unpaired tuberosity above, and two below. The most anterior pair are the olfactory lobes. From the anterior to posterior end they present four layers; first, olfactory nerve fibres with cell-like swellings upon them; second, coarsely granular neuroglia, with incipient glomeruli olfactorii, and large tripolar nerve cells; third, small usually unipolar cells each in its own space in the neuroglia; the whole collected into a rounded mass; fourth, nerve fibres proceeding from this mass to the second pair of tuberosities, the cerebral lobes, which consist of finely granular neuroglia, in which small cells are situated towards the circumference, and larger cells towards the centre, each of the latter contained in a lymph space.

Characteristics of the dynamics of the central nervous system and att ention function in workers of shoe production

2020 ◽  
pp. 64-68
Author(s):  
F. L. Azizova ◽  
U. A. Boltaboev
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Women Workers ◽  
Functional State ◽  
The Body ◽  
Conflict Of Interests ◽  
Professional Groups ◽  
Universal Device ◽  
The Central Nervous System ◽  
Working Day

The features of production factors established at the main workplaces of shoe production are considered. The materials on the results of the study of the functional state of the central nervous system of women workers of shoe production in the dynamics of the working day are presented. The level of functional state of the central nervous system was determined by the speed of visual and auditory-motor reactions, installed using the universal device chronoreflexometer. It was revealed that in the body of workers of shoe production there is an early development of inhibitory processes in the central nervous system, which is expressed in an increase in the number of errors when performing tasks on proofreading tables. It was found that the most pronounced shift s in auditory-motor responses were observed in professional groups, where higher levels of noise were registered in the workplace. The correlation analysis showed a close direct relationship between the growth of mistakes made in the market and the decrease in production. An increase in the time spent on the task indicates the occurrence and growth of production fatigue.Funding. The study had no funding.Conflict of interests. The authors declare no conflict of interests.

Neural Stem Cells to Glial Cells an Important Factor for Brain Injury

2020 ◽  
Author(s):  
Prithiv K R Kumar
Keyword(s):  
Stem Cells ◽  
Central Nervous System ◽  
Nervous System ◽  
Neural Stem Cells ◽  
Glial Cells ◽  
Brain Injuries ◽  
The Body ◽  
The Central Nervous System ◽  
Near Future

Stem cells have the capacity to differentiate into any type of cell or organ. Stems cell originate from any part of the body, including the brain. Brain cells or rather neural stem cells have the capacitive advantage of differentiating into the central nervous system leading to the formation of neurons and glial cells. Neural stem cells should have a source by editing DNA, or by mixings chemical enzymes of iPSCs. By this method, a limitless number of neuron stem cells can be obtained. Increase in supply of NSCs help in repairing glial cells which in-turn heal the central nervous system. Generally, brain injuries cause motor and sensory deficits leading to stroke. With all trials from novel therapeutic methods to enhanced rehabilitation time, the economy and quality of life is suppressed. Only PSCs have proven effective for grafting cells into NSCs. Neurons derived from stem cells is the only challenge that limits in-vitro usage in the near future.

scholarly journals VI. —Anaphylaxis and anaphylatoxins

1923 ◽  
Vol 211 (382-390) ◽  
pp. 273-315 ◽  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Guinea Pig ◽  
Anaphylactic Shock ◽  
The Body ◽  
Muscle Fibres ◽  
Direct Stimulation ◽  
Fundamental Conception ◽  
The Central Nervous System ◽  
Stimulation Of

In the study of the phenomena of anaphylaxis there are certain points on which some measure of agreement seems to have been attained. In the case of anaphylaxis to soluble proteins, with which alone we are directly concerned in this paper, the majority of investigators probably accept the view that the condition is due to the formation of an antibody of the precipitin type. Concerning the method, however, by which the presence of this antibody causes the specific sensitiveness, the means by which its interaction with the antibody produces the anaphylactic shock, there is a wide divergence of conception. Two main currents of speculation can be discerned. One view, historically rather the earlier, and first put forward by Besredka (1) attributes the anaphylactic condition to the location of the antibody in the body cells. There is not complete unanimity among adherents of this view as to the nature of the antibody concerned, or as to the class of cells containing it which are primarily affected in the anaphylactic shock. Besredka (2) himself has apparently not accepted the identification of the anaphylactic antibody with a precipitin, but regards it as belonging to a special class (sensibilisine). He also regards the cells of the central nervous system as those primarily involved in the anaphylactic shock in the guinea-pig. Others, including one of us (3), have found no adequate reason for rejecting the strong evidence in favour of the precipitin nature of the anaphylactic antibody, produced by Doerr and Russ (4), Weil (5), and others, and have accepted and confirmed the description of the rapid anaphylactic death in the guinea-pig as due to a direct stimulation of the plain-muscle fibres surrounding the bronchioles, causing valve-like obstruction of the lumen, and leading to asphyxia, with the characteristic fixed distension of the lungs, as first described by Auer and Lewis (6), and almost simultaneously by Biedl and Kraus (7). But the fundamental conception of anaphylaxis as due to cellular location of an antibody, and of the reaction as due to the union of antigen and antibody taking place in the protoplasm, is common to a number of workers who thus differ on details.

The Co-Ordination of Insect Movements

1957 ◽  
Vol 34 (3) ◽  
pp. 306-333
Author(s):  
G. M. HUGHES
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
The Body ◽  
The Other ◽  
Limb Amputation ◽  
Normal Movement ◽  
Thoracic Ganglia ◽  
Blatta Orientalis ◽  
The Central Nervous System ◽  
Leg Movements

I. The effects of limb amputation and the cutting of commissures on the movements of the cockroach Blatta orientalis have been investigated with the aid of cinematography. Detailed analyses of changes in posture and rhythm of leg movements are given. 2. It is shown that quite marked changes occur following the amputation of a single leg or the cutting of a single commissure between the thoracic ganglia. 3. Changes following the amputation of a single leg are immediate and are such that the support normally provided by the missing leg is taken over by the two remaining legs on that side. Compensatory movements are also found in the contralateral legs. 4. When two legs of opposite sides are amputated it has been confirmed that the diagonal sequence tends to be adopted, but this is not invariably true. Besides alterations in the rhythm which this may involve, there are again adaptive modifications in the movements of the limbs with respect to the body. 5. When both comrnissures between the meso- and metathoracic ganglia are cut, the hind pair of legs fall out of rhythm with the other four legs. The observations on the effects of cutting commissures stress the importance of intersegmental pathways in co-ordination. 6. It is shown that all modifications following the amputation of legs may be related to the altered mechanical conditions. Some of the important factors involved in normal co-ordination are discussed, and it is suggested that the altered movements would be produced by the operation of these factors under the new conditions. It is concluded that the sensory inflow to the central nervous system is of major importance in the co-ordination of normal movement.

Intrasellar Paraganglioma with Suprasellar Extension: Case Report

1998 ◽  
Vol 84 (3) ◽  
pp. 408-411 ◽  
Author(s):  
Maria Laura Del Basso De Caro ◽  
Antonella Siciliano ◽  
Paolo Cappabianca ◽  
Alessandra Alfieri ◽  
Enrico de Divitiis
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Case Report ◽  
Pelvic Floor ◽  
The Body ◽  
Benign Tumors ◽  
Sellar Region ◽  
The Central Nervous System ◽  
Base Of The Skull ◽  
Suprasellar Extension

Paragangliomas are usually benign tumors which can be found in many sites of the body, from the base of the skull down to the pelvic floor. In the central nervous system the sellar region is very rarely involved; only three well studied cases have been reported to date. We present the cytological, histological, histochemical, immunocytochemical and ultrastructural features of an intrasellar and suprasellar paraganglioma in an 84-year-old man.

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