scholarly journals The Fine Structure of Nerve Cells and Fibers, Neuroglia, and Sheaths of the Ganglion Chain in the Cockroach (Periplaneta americana)

1958 ◽  
Vol 4 (6) ◽  
pp. 731-742 ◽  
Author(s):  
Arthur Hess
Keyword(s):  
Fine Structure ◽  
Connective Tissue ◽  
Periplaneta Americana ◽  
Nerve Fibers ◽  
Nerve Cells ◽  
Cresyl Violet ◽  
Dark Cells ◽  
Electron Microscopes ◽  
Pass Through ◽  
Connective Tissue Sheath

The abdominal nerve cord of Periplaneta americana was studied utilizing light and electron microscopes. In the nerve cells, delicate granules, similar to those probably responsible for cytoplasmic basophilia, are evenly distributed in "dark" cells and clumped in "light" cells. Neuroglial cells are stained metachromatically by cresyl violet. The neuroglial cells have many processes which ramify extensively and are enmeshed to form overlapping layers. These imbricated processes ensheath the nerve cells; the inner layer of the sheath penetrates into the neuron and is responsible for the appearance of the trophospongium of Holmgren. Nerve fibers are embedded within glial cells and surrounded by extensions of the plasma membrane similar to mesaxons. Depending on their size, two or several nerve fibers may share a single glial cell. Nerve fibers near their terminations on other nerve fibers contain particles and numerous, large mitochondria. The ganglion is ensheathed by a thick feltwork of connective tissue and perilemmal cells. The abdominal connective has a thinner connective tissue sheath which is without perilemmal cells. The nerve fibers and sheaths in the connective become thinner as they pass through ganglia.

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 FINE STRUCTURE OF THE ELECTRIC ORGAN OF TORPEDO MARMORATA

1965 ◽  
Vol 24 (1) ◽  
pp. 129-141 ◽  
Author(s):  
Michael N. Sheridan
Keyword(s):  
Fine Structure ◽  
Connective Tissue ◽  
Basement Membrane ◽  
Intercellular Space ◽  
Electric Organ ◽  
Dorsal Surface ◽  
Ventral Surface ◽  
Nerve Fibers ◽  
Nerve Endings ◽  
Torpedo Marmorata

The fine structure of the electric organ of the fish Torpedo marmorata has been examined after osmium tetroxide or potassium permanganate fixation, acetone dehydration, and Araldite embedment. This organ consists of stacks of electroplaques which possess a dorsal noninnervated and a ventral richly innervated surface. Both surfaces are covered with a thin basement membrane. A tubular membranous network whose lumen is continuous with the extracellular space occupies the dorsal third of the electroplaque. Nerve endings, separated from the ventral surface of the electroplaque by a thin basement membrane, contain synaptic vesicles (diameter 300 to 1200 A), mitochondria, and electron-opaque granules (diameter 300 A). Projections from the nerve endings occupy the lumina of the finger-like invaginations of the ventral surface. The cytoplasm of the electroplaques contains the usual organelles. A "cellular cuff" surrounds most of the nerve fibers in the intercellular space, and is separated from the nerve fibre and its Schwann cell by a space containing connective tissue fibrils. The connective tissue fibrils and fibroblasts in the intercellular space are primarily associated with the dorsal surface of the electroplaque.

scholarly journals The Fine Structure of Degenerating Nerve Fibers, their Sheaths, and their Terminations in the Central Nerve Cord of the Cockroach (Periplaneta americana)

1960 ◽  
Vol 7 (2) ◽  
pp. 339-344 ◽  
Author(s):  
Arthur Hess
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Nerve Cord ◽  
Periplaneta Americana ◽  
Morphological Changes ◽  
Nerve Fibers ◽  
Thoracic Ganglion

The connectives above and below the second thoracic ganglion and nerves to and from the mesothoracic leg were severed in Periplaneta americana. Isolated ganglia and severed nerve cord were examined in the electron microscope. In the connectives, sheaths of degenerating fibers remain continuous but become thicker and more dense. There is increase in number and more haphazard disposition of the neuroglial processes which ensheath the axons. The cytoplasm contains vacuoles. Dense droplets normally intercalated between the layers of neuroglial processes ensheathing the axons are strikingly increased in number. The axoplasm with its organelles forms dense clumps. Mitochondria in axons are enlarged, the intramitochondrial matrix is more dense, and the internal folds are disorganized. In ganglia, mitochondrial changes in terminal parts of the axons appear similar to those described in the parent axons in the connective. The synaptic portions of nerve fibers appear very dense. Alterations of the sheath are minimal. Synaptic particles in the degenerating axoplasmic coagulum undergo only slight morphological changes and are still present up to 6 days after severance of their nerve fibers. It is difficult to assess whether there are any alterations in the total number of synaptic particles during degeneration.

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.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

A New High Intensity Grid Cap for RCA-EMU-3 Electron Microscopes

1968 ◽  
Vol 26 ◽  
pp. 316-317
Author(s):  
George Christov ◽  
Bolivar J. Lloyd
Keyword(s):  
Electron Beam ◽  
Electron Microscope ◽  
High Voltage ◽  
High Intensity ◽  
Electron Gun ◽  
Tungsten Filament ◽  
Fluorescent Screen ◽  
Electron Microscopes ◽  
Pass Through ◽  
Ground Potential

A new high intensity grid cap has been designed for the RCA-EMU-3 electron microscope. Various parameters of the new grid cap were investigated to determine its characteristics. The increase in illumination produced provides ease of focusing on the fluorescent screen at magnifications from 1500 to 50,000 times using an accelerating voltage of 50 KV.The EMU-3 type electron gun assembly consists of a V-shaped tungsten filament for a cathode with a thin metal threaded cathode shield and an anode with a central aperture to permit the beam to course the length of the column. The cathode shield is negatively biased at a potential of several hundred volts with respect to the filament. The electron beam is formed by electrons emitted from the tip of the filament which pass through an aperture of 0.1 inch diameter in the cap and then it is accelerated by the negative high voltage through a 0.625 inch diameter aperture in the anode which is at ground potential.

Neural and vascular architecture of the septum pellucidum: an anatomical study and considerations for safe endoscopic septum pellucidotomy

2020 ◽  
Vol 133 (3) ◽  
pp. 902-911
Author(s):  
Laszlo Barany ◽  
Cintia Meszaros ◽  
Oliver Ganslandt ◽  
Michael Buchfelder ◽  
Peter Kurucz
Keyword(s):  
Anatomical Study ◽  
Nerve Fibers ◽  
Septum Pellucidum ◽  
Cresyl Violet ◽  
Membranous Structure ◽  
Luxol Fast Blue ◽  
Fast Blue ◽  
Frontal Horn ◽  
Septal Nuclei ◽  
Fiber Dissection

OBJECTIVEThe septum pellucidum is a bilateral thin membranous structure representing the border between the frontal horns of the lateral ventricles. Its most examined components are the septal veins due to their surgical importance during endoscopic septum pellucidotomy (ESP), which is a well-accepted method for surgical treatment of unilateral hydrocephalus. It is widely accepted that the septum pellucidum contains nerve fibers as well, but interestingly, no anatomical study has been addressed to its neural components before. The aim of the present study was to identify these elements as well as their relations to the septal veins and to define major landmarks within the ventricular system for neurosurgical use.METHODSNine formalin-fixed human cadaveric brains (18 septa pellucida) were involved in this study. A central block containing both septa pellucida was removed and frozen at −30°C for 2 weeks in 7 cases. The fibers of the septum pellucidum and the adjacent areas including the venous elements were dissected under magnification by using homemade wooden spatulas and microsurgical instruments. In 2 cases a histological technique was used to validate the findings of the dissections. The blocks were sliced, embedded in paraffin, cut in 7-µm-thick slices, and then stained as follows: 1) with H & E, 2) with Luxol fast blue combined with cresyl violet, and 3) with Luxol fast blue combined with Sirius red.RESULTSThe septum pellucidum and the subjacent septum verum form the medial wall of the frontal horn of the lateral ventricle. Both structures contain nerve fibers that were organized in 3 groups: 1) the precommissural fibers of the fornix; 2) the inferior fascicle; and 3) the superior fascicle of the septum pellucidum. The area directly rostral to the postcommissural column of the fornix consisted of macroscopically identifiable gray matter corresponding to the septal nuclei. The histological examinations validated the findings of the authors’ fiber dissections.CONCLUSIONSThe nerve elements of the septum pellucidum as well as the subjacent septum verum were identified with fiber dissection and verified with histology for the first time. The septal nuclei located just anterior to the fornix and the precommissural fibers of the fornix should be preserved during ESP. Considering the venous anatomy as well as the neural architecture of the septum pellucidum, the fenestration should ideally be placed above the superior edge of the fornix and preferably dorsal to the interventricular foramen.

The neurophysiology of respiration in decapod crustacea. II. The sensory system

1969 ◽  
Vol 47 (3) ◽  
pp. 435-441 ◽  
Author(s):  
Valerie M. Pasztor
Keyword(s):  
Connective Tissue ◽  
Sensory Input ◽  
Respiratory Rhythm ◽  
Sensory System ◽  
Nerve Fibers ◽  
Rhythm Generator ◽  
Decapod Crustacea ◽  
New Type

The mechanoreceptors of the respiratory appendage were studied by histological and electrophysiological techniques.A new type of mechanoreceptor is described and named the "oval organ". It consists of a specialized oval patch of cuticle 1–2 mm in length which is traversed by a spine or longitudinal thickening. Closely applied to the cuticle is a pad of connective tissue richly supplied with dendrites from two large nerve fibers. The orientation of the spine and the dendrites ensures that the receptor responds preferentially to certain stresses or foldings of the oval organ. It lies at the base of the scaphognathite on the dorsal surface.No internal proprioceptors were observed. Movements of the appendage are signalled either by the oval organ, epidermal receptors, or hair sensilla.The possible effect of sensory input upon the central respiratory rhythm generator is discussed.

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