scholarly journals On the Origin of the Electric Organ in Malapterurus Electricus

1956 ◽  
Vol s3-97 (39) ◽  
pp. 455-463
Author(s):  
ALF G. JOHNELS
Keyword(s):  
Connective Tissue ◽  
Anterior Part ◽  
Electric Organ ◽  
Shoulder Girdle ◽  
Ventral Surface ◽  
Spinal Root ◽  
Electric Organs ◽  
Electric Fishes ◽  
Rostral Portion ◽  
Dermal Connective Tissue

The present study was made on two small specimens of Malapterurus electricus, of standard lengths 11.4 and 12.7 mm. As is well known, the postembryonic growth of electric organs in Malapterurus and other electric fishes takes place by an enlargement of the electric units and not by an increase in the number of the electric plates. In the present material, however, there is a multiplication of electric tissue elements in the rostral portion of the electric organ. The structure of this multiplication zone is described. In the anterior region the connective tissue membranes which surround the two halves of the electric organ form structures similar to tendons which are fixed to the ventral surface of the shoulder girdle on each side of the median line. A small deficiency on each side in the muscular wall in the same region was observed in adult specimens by Maurer. This deficiency is more evident in the young specimens studied in the present paper and it is covered from the outside by the multiplication zone of the electric organ. In this place the electric nerve joins the electric organ. The giant electric cell, the surface of which is penetrated by intracellular capillaries, is situated in the anterior part of the spinal cord and its axon emerges with the third ventral spinal root. In the multiplication zone the connective tissue membranes are completely independent of the dermal connective tissue and the space between the electric organ and the skin is of a conventional subdermal type. These circumstances strongly indicate that the electric organ is of myoblastic origin in Malapterurus as in all other electric fishes known in this respect. Nothing has been observed which supports the idea of an adenoid origin of the electric organ in Malapterurus.

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 third form electric organ discharge of electric eels

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jun Xu ◽  
Xiang Cui ◽  
Huiyuan Zhang
Keyword(s):  
High Voltage ◽  
Low Voltage ◽  
Electric Organ Discharge ◽  
Electric Organ ◽  
The Third ◽  
Electric Organs ◽  
Electric Eel ◽  
New Finding ◽  
Discharge Behavior ◽  
Unique Species

AbstractThe electric eel is a unique species that has evolved three electric organs. Since the 1950s, electric eels have generally been assumed to use these three organs to generate two forms of electric organ discharge (EOD): high-voltage EOD for predation and defense and low-voltage EOD for electrolocation and communication. However, why electric eels evolved three electric organs to generate two forms of EOD and how these three organs work together to generate these two forms of EOD have not been clear until now. Here, we present the third form of independent EOD of electric eels: middle-voltage EOD. We suggest that every form of EOD is generated by one electric organ independently and reveal the typical discharge order of the three electric organs. We also discuss hybrid EODs, which are combinations of these three independent EODs. This new finding indicates that the electric eel discharge behavior and physiology and the evolutionary purpose of the three electric organs are more complex than previously assumed. The purpose of the middle-voltage EOD still requires clarification.

Aberrations of dermal connective tissue in patients with cervical artery dissection (sCAD)

2008 ◽  
Vol 255 (3) ◽  
pp. 340-346 ◽  
Author(s):  
P. Uhlig ◽  
P. Bruckner ◽  
R. Dittrich ◽  
E. B. Ringelstein ◽  
G. Kuhlenbäumer ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Artery Dissection ◽  
Cervical Artery Dissection ◽  
Cervical Artery ◽  
Dermal Connective Tissue

TERMINOLOGY OF PALEOZOIC PLACODERM FISHES (ANTIARCHI) EXOSKELETAL ELEMENTS

2021 ◽  
Vol 43 (2) ◽  
pp. 195-201
Author(s):  
Sergey Moloshnikov ◽  
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Shoulder Girdle ◽  
Russian Language ◽  
Postcranial Skeleton ◽  
Incorrect Conclusion ◽  
Similar Term ◽  
Early Vertebrates ◽  
Language Literature ◽  
Dorsal Scute

The terminology and morphology of plates of the posterior part of the antiarch head shield (Placodermi, Antiarchi) are discussed. The terms «zatilochnaya» and «bokovaya (kraevaya) zatilochnaya» was previously accepted in antiarch skulls and are suggested for use in Russian-language literature. These terms are more correct and clearly define a position and development of these plates in the head shield of antiarchs. The titles «zagrivkovaya (nuchalnaya)» and «bokovaya zagrivkovaya (paranuchalnaya)», recently applied to them in Russian-language literature may indicate a connection in development with an anterior part of a trunk. A similar term is used for acipenserid exoskeleton. The acipenserid «nuchalnaya kost’» is located posterior to the «verchnezatilochnaya» (after Gurtovoi), and embryonically developed in an anterior part of the trunk over basidorsals and bones of the shoulder girdle. The name «pervaya spinnaya plastinka» (first dorsal scute: after Hilton and others) is also use for this bone. The term «zagrivkovaya plastinka» is used in other vertebrate skeletons, for example, in turtles; this name denotes the unpaired element of a carapace (postcranial skeleton). Using the terms «zagrivkovaya (nuchalnaya)» and «bokovaya zagrivkovaya (paranuchalnaya)» in the morphology of antiarchs and other placoderms may lead confusion in the terminology of skeletal elements at early vertebrates, incorrect conclusion of their homology, structure and development of the head shield of these unusual fishes.

SWELLING BEHAVIOUR OF THE CATCH CONNECTIVE TISSUE IN HOLOTHURIAN BODY WALL

1989 ◽  
Vol 143 (1) ◽  
pp. 71-85 ◽  
Author(s):  
JOHN P. EYLERS ◽  
ALAN R. GREENBERG
Keyword(s):  
Connective Tissue ◽  
Calcium Concentration ◽  
Body Wall ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Nacl Solution ◽  
Maximum Volume ◽  
Swelling Behaviour ◽  
Volume Increase ◽  
Dermal Connective Tissue

Swelling tests in a series of isotonic and isoionic solutions of varying calcium-tosodium ratios were conducted on isolated dermal connective tissue of the holothurian Thyonella gemmata Verrill. The tissue swelled rapidly and attained a maximum volume increase of approximately 40 % when transferred from distilled water to NaCl solution; however, the volume did not change significantly in isotonic CaCl2 solution. At Ca2+/Na+ ratios ≤0.04 the tissue swelled at its maximum rate. The rate decreased with increasing calcium concentration, until at Ca2+/Na+ ≥0.40 no detectable swelling occurred. Similar results were obtained for Pentacta pygmaea Goldfuss. When tissues previously swollen in NaCl were placed in CaC2, the volume decreased significantly. Uniaxial tensile tests indicated that the elastic modulus of the tissue was much greater in Ca2+ solutions than in Na+ solutions. We hypothesize that dermal stiffness in holothurians is regulated by cation-sensitive crosslinks

Activation of Dermal Connective Tissue in Scleroderma

1993 ◽  
Vol 25 (6) ◽  
pp. 511-518 ◽  
Author(s):  
Veli-Matti Kähäri
Keyword(s):  
Connective Tissue ◽  
Dermal Connective Tissue

Permeability of Dermal Connective Tissue in Adrenalectomized and Hypophysectomized Rats

Endocrinology ◽  
1965 ◽  
Vol 76 (3) ◽  
pp. 408-411 ◽  
Author(s):  
J. FABIANEK ◽  
A. HERP ◽  
W. PIGMAN
Keyword(s):  
Connective Tissue ◽  
Hypophysectomized Rats ◽  
Dermal Connective Tissue
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