Induction d'une queue et de parapodes surnuméraires par déviation de l'intestin chez les Nereidae (Annélides Polychètes)

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 329-343
Author(s):  
Par B. Boilly
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Cord ◽  
Body Wall ◽  
The Body ◽  
The Central Nervous System ◽  
Different Tissues

Supernumerary tail and parapodia induction by deviation of the intestine in nereids (Annelida: Polychaeta) Localized ablation of the intestine has been performed on normal and grafted specimens of the two polychaetes Nereis pelagica L. and Perinereis cultrifera G. with the following results: (1) In the absence of the intestine, segments are not regenerated but parapodia grow on the plane of section. (2) A segmented tail arises where the intestine is deviated; the regenerate we obtain in this case is of the ‘aneurogenic’ type and without anal cirri and parapodia. (3) These results suggest that caudal regeneration results from the association of different tissues (intestine and the body wall) whereas the nerve cord exerts an influence upon the organization of the regenerate. Likewise the caudal regeneration of parapodia is the consequence of the juxtaposition of a dorsal and a ventral body wall in the presence of the central nervous system.

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 Movements of the Proboscis in Glycera Dibranchiata Ehlers

1937 ◽  
Vol 14 (3) ◽  
pp. 290-301
Author(s):  
G. P. WELLS
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Body Wall ◽  
The Body ◽  
Inhibitory Influence ◽  
Spontaneous Movement ◽  
Arenicola Marina ◽  
Glycera Dibranchiata ◽  
The Central Nervous System ◽  
Nervous Conduction

1. The gut of Glycera consists of (a) the buccal tube, (b) the pharynx, containing the jaws with their associated muscles and glands and the principal stomatogastric ganglia, (c) the oesophagus, leading from the pharynx to (d) the intestine, in which digestion occurs. 2. An "isolated extrovert" preparation is described, consisting of the buccal tube, pharynx and oesophagus. The movements of the buccal tube and oesophagus are recorded separately. The preparation has the following properties: (a) The buccal tube shows vigorous, rapid contractions with a somewhat irregular rhythm. These contractions are due to impulses coming forwards from the pharynx, the buccal tube itself having little power of spontaneous movement. (b) The oesophagus shows tone-waves, on which more rapid contractions of small amplitude may be superposed. These contractions and tone-waves are due to impulses originating in the wall of the oesophagus itself. (c) In a few preparations only, synchronous movements of buccal tube and oesophagus were seen. The site of origin of this synchronous activity was not determined. 3. An "extrovert-body wall" preparation is described, in which the movements of the body wall and buccal tube are separately recorded while the normal nervous conduction paths between them remain intact. The preparation has the following properties: (a) In most cases the body wall shows slight movements only, and the buccal tube moves little or not at all. If, however, the buccal tube be cut across close to the mouth, it begins an irregular rhythm of vigorous contractions, due to impulses originating in the pharynx, which usually continues without diminution for hours. The quiescence of the buccal tube before this cut is made indicates that the central nervous system normally exerts an inhibitory influence on the pharynx. (b) In a few preparations, correlated outbursts of contraction in the body wall and buccal tube were seen. These outbursts, which possibly correspond to extrusion movements of the intact worm, are due to impulses originating in the central nervous system. 4. The results are compared with those previously obtained on Arenicola marina, and reported in an earlier paper.

Pharmacological Induction of Plasticization in the Abdominal Cuticle of Rhodnius

1974 ◽  
Vol 61 (3) ◽  
pp. 705-718
Author(s):  
STUART E. REYNOLDS
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Hormone Receptor ◽  
Body Wall ◽  
Direct Action ◽  
The Body ◽  
Malpighian Tubules ◽  
Diuretic Hormone ◽  
The Central Nervous System ◽  
The Relationship

Injections of 5-hydroxytryptamine (5-HT, serotonin) are found to cause plasticization of the abdominal cuticle of Rhodnius larvae. This plasticization is a direct action of 5-HT on some element in the body wall; the central nervous system is not required. It is probable that 5-HT acts directly at a receptor on the epidermal cells. The relationship between structure and plasticizing activity for a number of 5-HT analogues has been investigated. The receptor resembles other ‘classical’ 5-HT receptors in its requirements, but is unlike the 5-HT/diuretic hormone receptor of Rhodnius Malpighian tubules.

scholarly journals The visceral nervous system of the earthworm: I. Nerves controlling the tone of the alimentary canal

1943 ◽  
Vol 131 (864) ◽  
pp. 271-295 ◽  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Alimentary Canal ◽  
Body Wall ◽  
The Body ◽  
Nerve Supply ◽  
Rhythmic Movements ◽  
Indirect Control ◽  
Pharyngeal Plexus ◽  
The Central Nervous System

The alimentary canal of Lumbricus exhibits autonomous rhythmic movements, probably co-ordinated by nerve elements situated in its walls. The gut is subject to indirect control by extrinsic nerves which fall into two groups mutually antagonistic in their effects. Nerves which augment the tone of the gut muscles leave the central nervous system by the middle and posterior nerves of each segment and join nerve elements (apparently arranged as a plexus) situated in the peritoneum of the body wall, from which nerves pass to enter the gut by the ventro-lateral regions of each septum. Nerves which diminish the tone of the gut leave the central nervous system by the anterior, middle and posterior nerves of each segment and join nerve elements (also probably in the form of a plexus) situated in the muscular layer of the body wall, from which nerves arise to enter the gut via the dorso-lateral region of each septum. The alimentary canal receives another nerve supply from the peripharyngeal commissures of the central nervous system by means of a number of fine plexiform nerves partially embedded in the pharyngeal musculature of either side (pharyngeal plexus). The anatomical relationships of these nerves are described. The pharyngeal plexuses are shown to embody nerve elements which exert an indirect control over the gut, stimulation of these resulting in a fall in tone of all regions of the gut behind the pharynx. The nerve supply of the gut is compared with that which is known in other annelids, and the mechanism of indirect control is compared with that existing in vertebrates.

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 Larval Eclosion Hormone Neurones in Manduca Sexta: Identification of the Brain-Proctodeal Neurosecretory System

1989 ◽  
Vol 147 (1) ◽  
pp. 457-470 ◽  
Author(s):  
JAMES W. TRUMAN ◽  
PHILIP F. COPENHAVER
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Manduca Sexta ◽  
Nerve Cord ◽  
Release Site ◽  
Neurosecretory System ◽  
Nerve Activity ◽  
Eclosion Hormone ◽  
The Central Nervous System ◽  
The Brain

Larval and pupal ecdyses of the moth Manduca sexta are triggered by eclosion hormone (EH) released from the ventral nervous system. The major store of EH activity in the latter resides in the proctodeal nerves that extend along the larval hindgut. At pupal ecdysis, the proctodeal nerves show a 90% depletion of stored activity, suggesting that they are the major release site for the circulating EH that causes ecdysis. Surgical experiments involving the transection of the nerve cord or removal of parts of the brain showed that the proctodeal nerve activity originates from the brain. Retrograde and anterograde cobalt fills and immunocytochemistry using antibodies against EH revealed two pairs of neurons that reside in the ventromedial region of the brain and whose axons travel ipsilaterally along the length of the central nervous system (CNS) and project into the proctodeal nerve, where they show varicose release sites. These neurons constitute a novel neuroendocrine pathway in insects which appears to be dedicated solely to the release of EH.

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.

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