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.

The Golgi Material of the Neurones of the Central Nervous System of Sheep Infected with Louping-Ill

1947 ◽  
Vol s3-88 (1) ◽  
pp. 55-63
Author(s):  
R. A. R. GRESSON ◽  
I. ZLOTNIK
Keyword(s):  
Spinal Cord ◽  
Central Nervous System ◽  
Nervous System ◽  
Purkinje Cells ◽  
Medulla Oblongata ◽  
Motor Nerve ◽  
Pyramidal Cells ◽  
Cell Processes ◽  
The Central Nervous System ◽  
Louping Ill

1. The Golgi material of the pyramidal cells of the cerebral cortex, the Purkinje cells of the cerebellum, and the multipolar cells of the medulla oblongata and ventral horns of the spinal cord of the sheep is present as filaments and as irregularly shaped bodies. In some of the cells, particularly in the lamb (Sheep V), the Golgi material has the appearance of a network. As it is frequently present as separate bodies it is suggested that it may always consist of discrete Golgi elements which are sometimes situated in close proximity or in contact with one another. Filamentous Golgi elements are present in the basal part of the cell processes. 2. An examination of neurones from the corresponding regions of the central nervous system of sheep infected experimentally with louping-ill showed that the Golgi material undergoes changes consequent upon the invasion of the cells by the virus. The Golgi material undergoes hypertrophy, and at the same time there is a reduction in the number of filamentous Golgi elements and a reduction in the amount of Golgi substance present in the cell processes. These changes are followed by fragmentation. All the neurones of a particular region are not affected equally at the same time. The Golgi material of the Purkinje cells tends to form groups in the cytoplasm prior to fragmentation. In the multipolar cells of the medulla oblongata the hypertrophy of the Golgi material is not as great as in the other regions of the central nervous system. The Golgi material of the motor nerve-cells of the ventral horns of the spinal cord undergoes considerable hypertrophy which is followed by a grouping of the Golgi elements and fragmentation.

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.

Observations on the Chemical Composition of Myelin and the Smallest Size of Myelinated Nerve-Fibres in the Central Nervous System

1948 ◽  
Vol s3-89 (5) ◽  
pp. 89-102
Author(s):  
A. BRODAL ◽  
R. G. HARRISON
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Chemical Composition ◽  
Nile Blue ◽  
Nerve Fibres ◽  
Myelinated Nerve ◽  
Myelin Sheaths ◽  
The Central Nervous System

Baker's (1946) acid haematein and pyridine-extraction control tests, claimed to be specific for phospholipines (Baker, 1947), have been applied to various parts of the central nervous system of rats and man. The sudan black method for the detection of lipoids and the nile blue method for the staining of acidic lipoids have also been used. The findings are in agreement with older statements in the literature that myelin contains a considerable amount of phospholipines. It was impossible to determine whether galactolipines or neutral lipoids are also present. In the acid haematein-stained sections finer fibres were seen than when other stains for myelin sheaths are employed. Fibres with a diameter of 0.5 µ or even somewhat less were stained in various parts of the central nervous system of rats. It is regarded as probable from these findings that fibres down to 0.5 µ or even smaller possess a lipoid investment. These observations lend support to the now commonly accepted view that the distinction between myelinated and so-called unmyelinated fibres is arbitrary. Some observations are made, however, which indicate that the presence of truly unmyelinated fibres cannot be excluded.

scholarly journals Muscle receptor organs in the Paguridae

1952 ◽  
Vol 31 (2) ◽  
pp. 277-286 ◽  
Author(s):  
J. S. Alexandrowicz
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Nerve Fibres ◽  
Dorsal Wall ◽  
Muscle Receptor ◽  
Distal Process ◽  
Extensor Muscles ◽  
Receptor Organ ◽  
The Central Nervous System ◽  
Motor Nerves

In the dorsal wall of the abdomen in the Paguridae muscle receptor organs have been found similar to those in the Macrura. In each of the first to fifth abdominal segments there are two receptor units on each side. A receptor unit consists of a long thread-like muscle, and a nerve cell connected with this muscle and sending its axon towards the central nervous system. The muscles of each pair run close together in the layer of the dorsal (extensor) muscles, but are independent from the latter following a more or less different course.The nerve cells in each pair of muscle receptor organs are of two types. One of them has several very long distal processes expanding over one of the muscles. The other cell has one stout distal process giving off numerous but very short branches forming with their subdivisions a dense tuft of fibres terminating in the second muscle. The axons of the cells associate with one of the branches of motor nerves supplying the dorsal muscles and pass along these branches into the main nerve trunks of the respective segments.Each receptor organ is supplied by several nerve fibres coming from the central nervous system.

scholarly journals The Structure and Conduction Velocity of the Medullated Nerve Fibres of Prawns

1941 ◽  
Vol 18 (1) ◽  
pp. 50-54 ◽  
Author(s):  
W. HOLMES ◽  
R. J. PUMPHREY ◽  
J. Z. YOUNG
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Conduction Velocity ◽  
Myelin Sheath ◽  
Axon Diameter ◽  
Relative Thickness ◽  
Nodes Of Ranvier ◽  
Nerve Fibres ◽  
The Central Nervous System ◽  
Myelinated Fibres

1. The structure of the myelinated fibres of prawns is described, and the homologies of the nucleated sheath which lies between the axon and the fatty layer discussed. 2. The relative thickness of the myelin sheath increases with decrease in total diameter of the fibre along a curve similar in shape to that found in vertebrates and earthworms. 3. Nodes of Ranvier are found in the sheaths of most fibres of a diameter greater than about 13µ 4. The nodes are similar to those in vertebrate nerves in that the myelin sheath is interrupted at the node. 5. The conduction velocity of fibres in the central nervous system of axon diameter 26µ and total diameter 35µ is between 18 and 23 m. per sec., a rate faster than is found in the "unmyelinated" fibres of similar size in other crustacea.

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.

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