The Connective-Tissue Sheath of the Nervous System of Locusta migratoria: an Electron Microscope Study

1961 ◽  
Vol s3-102 (60) ◽  
pp. 463-467
Author(s):  
DOREEN E. ASHHURST ◽  
J. A. CHAPMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Electron Microscope ◽  
Connective Tissue ◽  
Electron Microscope Study ◽  
Locusta Migratoria ◽  
Inner Surface ◽  
Connective Tissue Sheath ◽  
Cellular Layer ◽  
Sheath Cells

The sheath is composed of an outer non-cellular layer, the neural lamella, and an inner layer of sheath cells. The neural lamella possesses a large number of collagen fibrils arranged in layers with differing orientations. The sheath cells are flattened on the inner surface of the lamella and the cytoplasm contains lipochondria, mitochondria, and small amounts of endoplasmic reticulum.

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.

scholarly journals The connective tissue sheath of the locust nervous system: its development in the embryo

1965 ◽  
Vol s3-106 (73) ◽  
pp. 61-73
Author(s):  
DOREEN E. ASHHURST
Keyword(s):  
Endoplasmic Reticulum ◽  
Nervous System ◽  
Connective Tissue ◽  
Lipid Droplets ◽  
Schistocerca Gregaria ◽  
Ganglion Cells ◽  
Embryological Development ◽  
Electron Dense Material ◽  
Connective Tissue Sheath ◽  
Sheath Cells

The embryological development of the connective tissue sheath around the nervous system has been investigated in Schistocerca gregaria. The sheath cells appear to be derived from outlying ganglion cells. The neural lamella is first visible when the embryo is 9 days old and it increases in thickness until hatching occurs on the twelfth day. It is produced entirely by the sheath cells. The sheath cells have numerous lipid droplets in their cytoplasm. Some neutral mucopolysaccharide and proteins are also present. The histochemical reactions of the neural lamella after its formation suggest that it is composed of collagenous proteins embedded in neutral mucopolysaccharides. The sheath cells are typical fibroblasts during the formation of the neural lamella. The cisternae of the endoplasmic reticulum are dilated into vesicles which contain a somewhat electron-dense material. No intracellular fibrils were observed. Collagen fibrils with banding of periodicity between 55 and 60 mµ. are seen in the neural lamella from 11 days onwards.

An Electron-Microscope Study of the Cytoplasmic Inclusions in the Neurones of Locusta Migratoria

1962 ◽  
Vol s3-103 (62) ◽  
pp. 147-153
Author(s):  
DOREEN E. ASHHURST ◽  
J. A. CHAPMAN
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Microscope Study ◽  
Electron Microscope Study ◽  
Locusta Migratoria ◽  
Cytoplasmic Inclusions ◽  
Double Membrane

The cytoplasmic inclusions of the neurones of adult Locusta migratoria have been examined in the electron microscope. The mitochondria are easily recognized by their cristae and outer double membranes. Electron-dense inclusions, also with an outer double membrane but possessing numerous closely spaced internal lamellae in various orientations, are probably small lipochondria. Larger and more diffuse inclusions comprising crescent-shaped aggregates of loosely packed parallel lamellae and vesicles are present; the possible significance of these larger inclusions is discussed. A system of numerous small vesicles distributed throughout the cytoplasm makes up the endoplasmic reticulum.

A Histochemical Study of the Connective-Tissue Sheath of the Nervous System of Periplaneta americana

1961 ◽  
Vol s3-102 (60) ◽  
pp. 455-461
Author(s):  
DOREEN E. ASHHURST
Keyword(s):  
Nervous System ◽  
Connective Tissue ◽  
Periplaneta Americana ◽  
Collagen Type ◽  
Histochemical Study ◽  
Type Protein ◽  
Connective Tissue Sheath ◽  
Sheath Cells

The connective-tissue sheath surrounding the nervous system of Periplaneta americana consists of two layers, the neural lamella and the sheath cells beneath it. The neural lamella is composed of a collagen-type protein and neutral muco-polysaccharide. The sheath cells possess numerous lipochondria and mitochondria; the former consist of phospholipid and some cerebroside. The cytoplasm of the sheath cells contains some RNA, glycogen, and lipid.

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 THE FIBROUS STRUCTURE OF THE NERVE AXON IN RELATION TO THE LOCALIZATION OF "NEUROTUBULES"

1950 ◽  
Vol 91 (5) ◽  
pp. 499-504 ◽  
Author(s):  
Francis O. Schmitt ◽  
Betty B. Geren
Keyword(s):  
Electron Microscope ◽  
Connective Tissue ◽  
Fibrous Structure ◽  
Thin Sections ◽  
Present Evidence ◽  
Nerve Axon ◽  
Connective Tissue Sheath ◽  
Formalin Fixed

In squid, frog, rat, and human nerves examined in thin sections with the electron microscope the axon contains, in addition to certain other particulates, characteristic filaments. These filaments have diameters ranging from about 100 to 200 Å and have indefinite length. They frequently have a nodose appearance due to the presence of discontinuities sometimes fairly regularly spaced along the filaments. This structure differs unmistakably from that of the dense-edged fibrils called "neurotubules" and it is clear that the latter are not axonic constituents. Though dense-edged fibrils can readily be demonstrated in fragmented formalin-fixed nerve preparations, they are seldom observed in thin sections. When such structures were seen in these experiments they were located in the connective tissue sheath. The present evidence offers no support for the view that "neurotubules" are structural entities of normal intact nerves.

Desiccation causes the proliferation of multicellular hairs, but not mucilage papillae, in Cryptothallus mirabilis (Hepatophyta): a correlated light and electron microscope study

1990 ◽  
Vol 68 (3) ◽  
pp. 697-706 ◽  
Author(s):  
Jeffrey G. Duckett ◽  
Karen S. Renzaglia ◽  
Keith Pell
Keyword(s):  
Endoplasmic Reticulum ◽  
Electron Microscope ◽  
Acid Phosphatase ◽  
Endophytic Fungus ◽  
Electron Microscope Study ◽  
Secretory Phase ◽  
Golgi Bodies ◽  
Dense Cytoplasm ◽  
Thin Walled ◽  
Multicellular Hair

When Cryptothallus dries out over periods of 4–20 days, the dorsal surfaces of the thalli become covered with multicellular hairs. The distribution of mucilage papillae and the endophytic fungus are not affected by desiccation. The hairs are thin walled and highly vacuolated whereas the mucilage papillae, like their secretory counterparts in Marchantia and mosses, are thick walled with dense cytoplasm containing stacks of endoplasmic reticulum and numerous Golgi bodies. Cytochemistry shows that the secretion is rich in carbohydrates and is derived from Golgi vesicles. After an active secretory phase, senescence of the mucilage papillae is associated with acid phosphatase activity. Key words: Aneura, Cryptothallus, desiccation, liverwort, mucilage papilla, multicellular hair, ultrastructure.

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