scholarly journals EFFECT OF THE CONNECTIVE TISSUE SHEATH ON THE VALUE OF THE ACCOMMODATION CONSTANT λ OF A NERVE FIBER

1951 ◽  
Vol 2 ◽  
pp. 270-276 ◽  
Author(s):  
MASAYASU SATO
Keyword(s):  
Connective Tissue ◽  
Nerve Fiber ◽  
Connective Tissue Sheath

scholarly journals The Ultrastructure of the Perineurium in two Insect Species, Carausius Morosus and Periplaneta Americana

1967 ◽  
Vol 2 (1) ◽  
pp. 119-128
Author(s):  
S. H. P. MADDRELL ◽  
J. E. TREHERNE
Keyword(s):  
Connective Tissue ◽  
Periplaneta Americana ◽  
Fluid Transport ◽  
Insect Species ◽  
Carausius Morosus ◽  
Insect Central Nervous System ◽  
Connective Tissue Sheath ◽  
Extracellular Sodium ◽  
Perineurial Cells ◽  
Cellular Layer

The organization of the perineurium in two insect species (Carausius morosus and Periplaneta americana) has been examined with the electron microscope. In both species this cellular layer has been found to possess an extensive system of tortuous channels between the lateral cell walls. These channels are open at the outer margin adjacent to the fibrous connective-tissue sheath, but appear to be closed at the inner margin by regions of septate desmosomes and/or ‘tight’ junctions. There is an increased surface area at the inner margin of the perineurial cells produced by the presence of long inwardly directed flanges. An electron-dense coat has also been identified on the cytoplasmic side of the type II perineurial cell membranes at points of contact with the underlying extracellular system and at the outer surface adjacent to the connective-tissue sheath. This organization of the perineurium is strikingly similar to that observed in a variety of fluid-secreting epithelia and its possible function in fluid transport is discussed in relation to the available evidence on the physiology of the insect central nervous system. It is suggested, contrary to some earlier suppositions, that the perineurium may not be primarily involved in the control of the extracellular sodium level and that this regulation may be effected at a deeper level in the central nervous tissues.

scholarly journals A case of Giant Perifollicular Fibroma - a Diagnostic Challenge

2020 ◽  
Vol 12 (1) ◽  
pp. 19-21
Author(s):  
Raghavendra Rao ◽  
Srilatha Parampalli Srinivas ◽  
Varsha M. Shetty
Keyword(s):  
Connective Tissue ◽  
Head And Neck ◽  
Neck Region ◽  
Diagnostic Challenge ◽  
Head And Neck Region ◽  
Internal Malignancy ◽  
Essential Tool ◽  
Proliferative Lesion ◽  
Connective Tissue Sheath

AbstractPerifollicular fibroma (PFF) is a rare proliferative lesion originating from the perifollicular connective tissue sheath. It may be congenital or acquired manifesting as skin colored to pink, asymptomatic papules of 1-5 mm in size. They are commonly distributed in the head and neck region. Multiple PFFs may be associated with internal malignancy or as a part of Birt-Hogg-Dube syndrome. Histopathology serves as an essential tool in clinching the diagnosis. Herein we report a case of giant congenital PFF.

Subcutaneous reaction to silicone in ventriculoperitoneal shunts

1974 ◽  
Vol 41 (3) ◽  
pp. 367-371 ◽  
Author(s):  
Oscar Sugar ◽  
Orville T. Bailey
Keyword(s):  
Cerebrospinal Fluid ◽  
Connective Tissue ◽  
Fibrous Connective Tissue ◽  
Subcutaneous Implantation ◽  
Content Type ◽  
Ventriculoperitoneal Shunts ◽  
Silicone Tubing ◽  
Connective Tissue Sheath ◽  
Fine Print

✓Silicone tubing (Silastic) used for ventriculoperitoneal shunts induces a fibrous connective tissue sheath around the tubing in children and adults. Two children examined 8 and 3 years after subcutaneous implantation showed a complete tube of dense fibrous connective tissue around the silicone tubing. The reaction was entirely quiescent. These tubes of connective tissue were apparently capable of conveying cerebrospinal fluid for some months after the silicone tubing was disconnected from the pump or pulled out of the abdomen.

The Connective Tissue Sheath of the Locust Nervous System: A Histochemical Study

1959 ◽  
Vol s3-100 (51) ◽  
pp. 401-412
Author(s):  
DOREEN E. ASHHURST
Keyword(s):  
Nervous System ◽  
Connective Tissue ◽  
Collagen Type ◽  
Histochemical Study ◽  
Locusta Migratoria ◽  
System A ◽  
Large Numbers ◽  
Connective Tissue Sheath ◽  
Cellular Layer ◽  
Sheath Cells

The connective tissue sheath surrounding the nervous system of Locusta migratoria has been studied histochemically. It consists of an outer non-cellular layer, the neural lamella, and an inner layer of cells, the sheath-cells. The neural lamella has been identified as being composed of a collagen-type protein and neutral mucopolysaccharide on the evidence of its histochemical reactions and the identification of hydroxyproline by paper chromatography in a hydrolysate of the neural lamella. The sheath-cells possess large numbers of lipochondria composed of phospholipids and cerebrosides, and small spherical mitochondria. The cytoplasm also contains lipids (some of which may be cerebrosides), glycogen, and RNA.

Studies on Locust Neuromuscular Physiology in Relation to Glutamic Acid

1974 ◽  
Vol 60 (3) ◽  
pp. 673-705 ◽  
Author(s):  
A. N. CLEMENTS ◽  
TERRY E. MAY
Keyword(s):  
Amino Acids ◽  
Connective Tissue ◽  
Glutamic Acid ◽  
Diffusion Barrier ◽  
Muscle Fibres ◽  
Magnesium Ions ◽  
Calcium And Magnesium ◽  
Nerve Muscle ◽  
Connective Tissue Sheath ◽  
Calcium And Magnesium Ions

1. Two nerve-muscle preparations were used to investigate the physiology of the locust retractor unguis muscle in relation to L-glutamic acid. These were an ‘isolated preparation’, in which the muscle and its nerve were dissected out, and a ‘perfusedfemur preparation’, in which the muscle suffered no mechanical disturbance. 2. Exposure of the nerve--muscle preparations to glutamate caused a variety of responses, some of which were shown to be abnormal and due to the experimental conditions. 3. When locust femora were perfused with saline or haemolymph the retractor unguis muscles were much more severely affected by glutamate if the hydrostatic pressure was slightly raised. At raised pressures the perfused-femur preparations were particularly prone to give repetitive and spontaneous contractions. 4. Analysis of haemolymph from adult male locusts showed that it contained, on average, 0-2 mmol/1 L-glutamate, 45 mol/1 total non-peptide amino acids, 5-0 mmol/1 calcium, and 11-6 mmol/1 magnesium. It was calculated that approximately 50% of the calcium and 75% of the magnesium ions are bound to amino acids, and that approximately 25% of the glutamic acid is bound to divalent metal ions. 5. The isolated preparations were severely affected by glutamate at the concentration at which it occurs in haemolymph, and it was concluded that in the intact locust some mechanism must protect the neuromuscular synapses from haemolymphg lutamate. No evidence could be obtained of the sequestration of glutamate by haemocytes, or of binding of glutamate to haemolymph proteins. 6. Calcium and magnesium ions reduced the sensitivity of nerve-muscle preparations to glutamate to a greater extent than could be accounted for by the formation of amino acid-metal complexes. This suggests that the protection afforded by calcium and magnesium involves an interaction of the metal ions with the neuromuscular system itself. 7. The retractor unguis muscle was much less sensitive to glutamate when it was contained within an undissected femur than in an isolated preparation. It was concluded that the muscle is normally protected from haemolymph glutamate by a diffusion barrier which is damaged on dissection. 8. Comparison of the fine structure of retractor unguis muscles, fixed either after dissection or while still contained within the femur, showed that dissection normally caused a partial separation of muscle fibres and damage to the connective tissue sheath, with the resultant exposure of some nerve endings. The connective tissue sheath may constitute the postulated diffusion barrier. 9. The excitatory synapses of the locust retractor unguis muscle are believed to be isolated from haemolymph glutamate by a diffusion barrier, which is tentatively identified with the connective tissue sheath that binds the muscle fibres together. Calcium and magnesium ions reduce the sensitivity of nerve-muscle preparations to glutamate, and may have such a role in the living insect.

Myoneural Junctions in the Connective Tissue Sheath of a Molluscan Ganglion

Nature ◽  
1968 ◽  
Vol 219 (5161) ◽  
pp. 1371-1372 ◽  
Author(s):  
P. R. BENJAMIN ◽  
A. PEAT
Keyword(s):  
Connective Tissue ◽  
Connective Tissue Sheath

Innervation of vibrissa follicles in the marsupial Trichosurus vulpecula

1974 ◽  
Vol 22 (3) ◽  
pp. 263 ◽  
Author(s):  
DE Hollis ◽  
AG Lyne
Keyword(s):  
Epithelial Cells ◽  
Connective Tissue ◽  
Outer Layer ◽  
Light And Electron Microscopy ◽  
Sensory Receptor ◽  
Merkel Cell ◽  
Myelinated Nerves ◽  
Sensory Receptor Cells ◽  
A Chain ◽  
Connective Tissue Sheath

The innervation of the mystacial vibrissa follicles in the adult brush-tailed possum, T. vulpecula, has been studied by light and electron microscopy. One to five large nerve trunks penetrate the lower part of the follicle capsule and divide many times as they ascend and completely envelop the con- nective tissue sheath of the follicle. As many as 500 myelinated nerves have been observed in the mid region of the largest follicles. Above the mid region, most of the nerves move closer to the centre of the follicle and finally terminate within or near the outer layer of epithelial cells. Four main types of nerve endings have been observed: (1) Sensory receptor cells, called Merkel cells, with their associated neurites are numerous within the outer layer of epithelial cells. (2) Palisade endings, which are less common than the Merkel cell-neurite complexes, surround the upper part of the glassy membrane of the follicle. In transverse section each palisade ending appears as a flattened central neurite partially enveloped on either side by Schwann cell processes. (3) Bulbous endings occur in both the connective tissue sheath and in the outer layer of follicle epithelial cells. They are larger than types (1) and (2) and their ultrastructure varies markedly. (4) Compound endings occur within the connective tissue sheath of the follicle. They are uncommon but large and are composed of a chain of bulbous units joined by nerves; the entire ending may be encapsulated. Within each unit there is a tangle of nerve fibres. The Merkel cell-neurite complexes and the palisade endings in T. vulpecula are remarkably similar to those of eutherian mammals, suggesting that such sensory structures were features of primitive mammals.

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