On the Question of Nervous Syncytia: Lack of Axon Fusion in Two Insect Sensory Nerves

1969 ◽  
Vol 4 (1) ◽  
pp. 39-53
Author(s):  
R. A. STEINBRECHT
Keyword(s):  
Electron Micrographs ◽  
Sensory Nerves ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Sense Cell ◽  
Average Fibre ◽  
The Brain

Electron micrographs of insect antennal nerves reveal that 98% of the nerve fibres are below 0.5 µ in diameter and are packed in bundles of naked axons without individual glia sheaths (average fibre calibre: 0.3 µ in Bombyx, 0.12 µ in Rhodnius). Re-examination of earlier light-microscopic fibre countings, which led to the hypothesis of axon fusion in insect sensory nerves, is now necessary. In the two nerves studied, each antennal sense cell is individually connected with the brain by its own axon. The results are compared with other cases of proposed axon fusion (e.g. giant fibre systems) and the physiological consequences are discussed.

Glucuronyl 3-sulfate occurs exclusively on distal unmyelinated terminals of selected sensory neurons in the peripheral nervous system

1995 ◽  
Vol 53 ◽  
pp. 958-959
Author(s):  
S.S. Spicer ◽  
B.A. Schulte
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cerebral Cortex ◽  
Peripheral Nervous System ◽  
Sensory Neurons ◽  
Sensory Nerves ◽  
Tissue Antigens ◽  
The Central Nervous System ◽  
The Brain ◽  
Leu 7

Generation of monoclonal antibodies (MAbs) against tissue antigens has yielded several (VC1.1, HNK- 1, L2, 4F4 and anti-leu 7) which recognize the unique sugar epitope, glucuronyl 3-sulfate (Glc A3- SO4). In the central nervous system, these MAbs have demonstrated Glc A3-SO4 at the surface of neurons in the cerebral cortex, the cerebellum, the retina and other widespread regions of the brain.Here we describe the distribution of Glc A3-SO4 in the peripheral nervous system as determined by immunostaining with a MAb (VC 1.1) developed against antigen in the cat visual cortex. Outside the central nervous system, immunoreactivity was observed only in peripheral terminals of selected sensory nerves conducting transduction signals for touch, hearing, balance and taste. On the glassy membrane of the sinus hair in murine nasal skin, just deep to the ringwurt, VC 1.1 delineated an intensely stained, plaque-like area (Fig. 1). This previously unrecognized structure of the nasal vibrissae presumably serves as a tactile end organ and to our knowledge is not demonstrable by means other than its selective immunopositivity with VC1.1 and its appearance as a densely fibrillar area in H&E stained sections.

Propagation of electrical signals along giant nerve fibres

1952 ◽  
Vol 140 (899) ◽  
pp. 177-183 ◽  
Keyword(s):  
Sea Water ◽  
Giant Axon ◽  
High Concentration ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Electrical Signals ◽  
Small Fibre ◽  
The Central Nervous System ◽  
Good Conductor ◽  
Ionic Movement

In this part of the discussion we shall attempt to describe the way in which electrical signals are propagated along the giant nerve fibres of squids and cuttlefish. These fibres consist of cylinders of protoplasm, 0.2 to 0.6 mm in diameter, and ire bounded by a thin membrane which acts as a barrier to ionic movement. The protoplasm, or axoplasm as it is commonly called, is an aqueous gel which is a reasonably good conductor of electricity. It contains a high concentration of K + and a low concentration of Na + and Cl - , this situation being the reverse of that in the animal’s blood or sea water. Axons which are left in sea water slowly lose potassium and gain sodium. This process takes about 24 hours and is roughly 80 000 times slower than the diffusion of ions out of a cylinder of gelatin of the same size. The interchange of sodium and potassium is very greatly accelerated by stimulating the fibres. Experiments with tracers, such as those made by Keynes & Lewis (1951) or Rothenberg (1950), allow the interchange to be measured quantitatively, and there is general agreement that the impulse is associated with an entry of 3 to 4 µ µ mol of Na + through 1 cm 2 of membrane and an exit of a corresponding quantity of K + . These quantities are very small compared with the total number of ions inside the fibre. In the giant axon of the squid the quantity of potassium lost in each impulse corresponds to only about 1 millionth if the total internal potassium. One would therefore expect that a giant fibre should be able to carry a great many impulses without recharging its batteries by metabolism. On the other hand, a very small fibre such as a dendrite in the central nervous system should be much more dependent on metabolism since the ratio of surface to volume may be nearly 1000 times greater.

CSF Monoamines in Autistic Syndromes and Other Pervasive Developmental Disorders of Early Childhood

1987 ◽  
Vol 151 (1) ◽  
pp. 89-94 ◽  
Author(s):  
C. Gillberg ◽  
L Svennerholm
Keyword(s):  
Neurodevelopmental Disorders ◽  
Pervasive Developmental Disorders ◽  
Developmental Disorders ◽  
Homovanillic Acid ◽  
Monoamine Metabolites ◽  
Autistic Children ◽  
Nerve Fibres ◽  
Normal Children ◽  
The Brain ◽  
Childhood Psychoses

Spinal fluid concentrations of the three major monoamine metabolites were examined in 25 infantile autistic children and 12 children with other childhood psychoses, and were contrasted with results obtained in normal children and in groups of children with neurological and neurodevelopmental disorders. Autistic children showed absolute and relative increases of the dopamine metabolite homovanillic acid. The group with other childhood psychoses also showed an increase in HVA level; in this group there were also indications of high levels of serotonin and norepinephrine metabolites. The results are discussed in the context of a pathogenetic model for autism involving hyperfunction of dopaminergic nerve fibres in the brain stem-mesolimbic system.

scholarly journals Optogenetic Activation of Type III Taste Cells Modulates Taste Responses

2020 ◽  
Vol 45 (7) ◽  
pp. 533-539
Author(s):  
Aurelie Vandenbeuch ◽  
Courtney E Wilson ◽  
Sue C Kinnamon
Keyword(s):  
Light Response ◽  
Sensory Nerves ◽  
Taste Bud ◽  
Chorda Tympani ◽  
Chorda Tympani Nerve ◽  
Type Iii ◽  
Nonspecific Effects ◽  
Taste Cells ◽  
Specific Stimulation ◽  
The Brain

Abstract Studies have suggested that communication between taste cells shapes the gustatory signal before transmission to the brain. To further explore the possibility of intragemmal signal modulation, we adopted an optogenetic approach to stimulate sour-sensitive (Type III) taste cells using mice expressing Cre recombinase under a specific Type III cell promoter, Pkd2l1 (polycystic kidney disease-2-like 1), crossed with mice expressing Cre-dependent channelrhodopsin (ChR2). The application of blue light onto the tongue allowed for the specific stimulation of Type III cells and circumvented the nonspecific effects of chemical stimulation. To understand whether taste modality information is preprocessed in the taste bud before transmission to the sensory nerves, we recorded chorda tympani nerve activity during light and/or chemical tastant application to the tongue. To assess intragemmal modulation, we compared nerve responses to various tastants with or without concurrent light-induced activation of the Type III cells. Our results show that light significantly decreased taste responses to sweet, bitter, salty, and acidic stimuli. On the contrary, the light response was not consistently affected by sweet or bitter stimuli, suggesting that activation of Type II cells does not affect nerve responses to stimuli that activate Type III cells.

CELLULAR LOCALIZATION OF A PROLACTIN-LIKE ANTIGEN IN THE RAT BRAIN

1979 ◽  
Vol 83 (2) ◽  
pp. 261-NP ◽  
Author(s):  
G. TOUBEAU ◽  
J. DESCLIN ◽  
M. PARMENTIER ◽  
J. L. PASTEELS
Keyword(s):  
Rat Brain ◽  
Cellular Localization ◽  
Female Rats ◽  
Nerve Fibres ◽  
Male And Female ◽  
Immunoreactive Material ◽  
Paraventricular Nuclei ◽  
Male And Female Rats ◽  
The Brain

The distribution of immunoreactive neurones and fibres was studied in rat brain using an antiserum to rat prolactin. Neurones containing the immunoreactive material were localized in the arcuate, ventromedial, premamillary, supraoptic and paraventricular nuclei of the hypothalamus. Immunoreactive nerve fibres were widely distributed within the brain. No differences were observed in labelling between male and female rats, or as a consequence of hypophysectomy.

The Effect of the Mammalian Neuropeptide, Gastrin-Releasing Peptide (GRP), on Gastrointestinal and Pancreatic Hormone Secretion in Man

1983 ◽  
Vol 65 (4) ◽  
pp. 365-371 ◽  
Author(s):  
Susan M. Wood ◽  
Roland T. Jung ◽  
Joan D. Webster ◽  
Mohammed A. Ghatei ◽  
Thomas E. Adrian ◽  
...  
Keyword(s):  
Hormone Secretion ◽  
Significant Elevation ◽  
Plasma Gastrin ◽  
Nerve Fibres ◽  
Selective Effect ◽  
Specific Location ◽  
Gastrin Releasing Peptide ◽  
Pancreatic Hormone ◽  
Mammalian Peptide ◽  
The Brain

1. Gastrin-releasing peptide, a newly isolated mammalian peptide similar in its structure and actions to the amphibian peptide, bombesin, has recently been localized to nerves in the brain, gut and pancreas. The present study investigates its effects on gut and pancreatic peptides in man. 2. Intravenous infusion of 0.7 and 2.9 pmol min−1 kg−1 produced significant elevation of plasma gastrin, cholecystokinin-like immuno- reactivity and neurotensin. It was found also to potentiate glucose-dependent insulin secretion. 3. Its specific location in nerve fibres in the proximal gut and pancreas and its selective effect on gastroenteropancreatic peptides may favour its role as a physiological regulatory neuropeptide.

THE RESPONSE OF 5′-NUCLEOTIDASE IN THE BRAIN TO OESTROGEN ADMINISTRATION IN THE GROWING RAT

1955 ◽  
Vol 12 (4) ◽  
pp. 231-235 ◽  
Author(s):  
D. NAIDOO ◽  
H. REY
Keyword(s):  
Normal Saline ◽  
Female Rats ◽  
Nucleotidase Activity ◽  
Nerve Fibres ◽  
Experimental Animals ◽  
Minimum Dose ◽  
Growing Rat ◽  
Similar Quantity ◽  
The Brain

SUMMARY After preliminary experiments to determine the minimum dose and optimum age at which invariable oestrogen-induced nucleotidase activity could be induced, six female rats aged 5 days were injected subcutaneously with 0·25 mg oestradiol monobenzoate for 10 days. Six female litter-mates injected with a similar quantity of normal saline were used as controls. The brains of these animals were examined histologically for 5′-nucleotidase activity. It was found that the activity of 5′-nucleotidase was increased considerably, the nerve fibres in the brains of the experimental animals being in this respect indistinguishable from the nerve fibres of normal 30-day-old animals, while the control animals showed no change from the normal. Further, nuclei which show poor 5′-nucleotidase activity in the normal 30-day-old rat were strongly active in the brains of 15-day-old experimental animals. In this respect there was no difference between the oestrogen-treated rats and controls of the same age. The significance of the results is discussed.

scholarly journals XI. The giant nerve cells and fibres of Halla parthenopeia

1909 ◽  
Vol 200 (262-273) ◽  
pp. 427-521 ◽  
Keyword(s):  
Nerve Cord ◽  
Transverse Section ◽  
Giant Cells ◽  
Nerve Cells ◽  
The Other ◽  
Striking Difference ◽  
Nerve Fibres ◽  
Giant Fibre ◽  
Giant Fibres ◽  
And Function

The giant nerve fibres, which form so prominent a feature in the transverse section of the nerve cord of many Annelids, were first observed in these animals by Clapaède in 1861, who, however, regarded them as canals. They were first recognised as nervous elements—“riesige dunkelrandige Nervenfasern”—by Leydig in 1864. Since then their nervous nature has been almost alternately affirmed and denied, and many widely divergent views have been advanced regarding their morphology and function. The connection of giant fibres with certain giant nerve cells was first shown in the case of Halla parthenopeia , by Spengel, in 1881. Although many other workers have investigated these elements, information is still lacking regarding several fundamental points of their structure. For instance, nothing is known regarding the neurofibrillæ of the giant cells, and although these conducting elements have been seen by five observers in the giant fibres of earthworms, there is a striking difference in their accounts: two of them refer to the presence of several neurofibrillæ, while the others describe or figure only a single fibril in each giant fibre. Further, no information is available regarding the place and mode of origin of these neurofibrillæ or their relations to other nerve elements. This defect is, no doubt, due largely to the difficulties attending the investigation of these remarkable cells and fibres; indeed, the failure of the methods usually adopted for staining nerve cells and fibres in other animals, to disclose nervous elements in the giant cells and fibres, has been held, for instance, by yon Lenhossék and Retzius, to disprove their nervous nature. The present investigation was commenced in 1900 with the view of determining the character and arrangement of the neurofibrillæ of the giant cells and fibres and the relations of these elements to the other elements of the nerve cord.

A Microscopic Demonstration of the Normal and Pathological Histology of Mesoglia Cells

1900 ◽  
Vol 46 (195) ◽  
pp. 724-724 ◽  
Author(s):  
Ford Robertson
Keyword(s):  
Cell Body ◽  
Brain Structure ◽  
Grey Matter ◽  
Brain Cells ◽  
Nerve Fibres ◽  
Pathological Conditions ◽  
Exact Function ◽  
Microscopic Demonstration ◽  
A Cell ◽  
The Brain

Dr. Clouston in the unavoidable absence of Dr. Ford Robertson made the following remarks:—The first fact that I have to direct the attention of the meeting to is that Dr. Ford Robertson has devised a new method of examining nerve-tissues by depositing platinum in them. By the use of this platinum method he has demonstrated, amongst other things, that what is called the neuroglia is composed of two sets of elements instead of one, as is generally considered. The neuroglia, as exhibited by this and other methods, is attached to the arteries, to the fibres, and to the brain-cells, forming a generally supporting medium. Dr. Robertson has discovered that in addition to this there is another set of cells, which he has called the mesoglia cells, consisting in a typical form of a cell-body, a nucleus and a number of processes. These processes are in no way connected either with the vascular substance or with the nerve-cells or the nerve-fibres. The mesoglia cells are entirely different from neuroglia cells in appearance, and are found in both the white and grey matter, and in such abundance that Dr. Robertson thinks that there are as many mesoglia cells as there are neuroglia cells existing all through the brain. Sometimes they have no processes, sometimes two processes, but the illustrations show a typical mesoglia cell from the dog and from man. The exact function of these mesoglia cells we certainly do not know, but they certainly do not act in any way as a support to the general brain structure. The mesoglia cells seem to have a phagocyte action in certain pathological conditions. They supply, if not all, at least the greater part of the amyloid bodies which are found in some of the chronic brain degenerations. I think you will agree that it is very important that Dr. Ford Robertson should have discovered a new element in the brain, the particular use of which will doubtless be demonstrated by some of the large number of enthusiastic workers on this subject.

scholarly journals Demonstration of Extracellular Space by Freeze-Drying in the Cerebellar Molecular Layer

1966 ◽  
Vol 1 (2) ◽  
pp. 223-228
Author(s):  
A. VAN HARREVELD ◽  
S. K. MALHOTRA
Keyword(s):  
Tight Junctions ◽  
Electron Micrographs ◽  
Extracellular Space ◽  
Freeze Drying ◽  
Circulatory Arrest ◽  
Molecular Layer ◽  
Freeze Substitution ◽  
Appreciable Amount ◽  
Nerve Fibres ◽  
Cerebellar Molecular Layer

In electron micrographs of the molecular layer of the mouse cerebellum frozen within 30 sec of circulatory arrest and subsequently dried at -79 °C an appreciable extracellular space was found between the axons of the granular cells. Tight junctions were regularly observed between pre- and postsynaptic structures and the enveloping glia cells. In micrographs of cerebellum frozen 8 min after decapitation the space between the axons was absent and tight junctions between the nerve fibres were almost exclusively encountered. The extracellular space of asphyxiated and non-asphyxiated tissue in electron micrographs of frozen-dried material is similar to the space in comparable tissues treated by freeze-substitution. These observations suggest that there is an appreciable amount of extracellular material in oxygenated, living tissue whichis taken up by cellular elements during asphyxiation.

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