Organization of the Giant Axons of the Cockroach Periplaneta Americana

1969 ◽  
Vol 50 (3) ◽  
pp. 615-627
Author(s):  
M. E. SPIRA ◽  
I. PARNAS ◽  
F. BERGMANN
Keyword(s):  
Nerve Cord ◽  
Periplaneta Americana ◽  
Thoracic Ganglion ◽  
American Cockroach ◽  
Abdominal Ganglion ◽  
Common Pathway ◽  
Average Delay ◽  
Giant Axons ◽  
Stimulation Of

1. Stimulation of the connectives between the suboesophageal and prothoracic ganglia of the American cockroach induced ipsilateral descending spikes in the abdominal giant axons with an average delay of 0·6 msec, per thoracic ganglion. 2. Nicotine at 5 µg./ml. had no effect on conduction in the abdomen but blocked ascending responses sequentially at the 6th abdominal ganglion then at the levels of T1; T2, and T3. 3. Simultaneous descending and ascending impulses resulted in mutual extinction along the nerve cord with the point of collision depending on the interval between stimuli. 4. It is suggested that a common pathway subserves ascending and descending giant impulses and models for bi-directional conduction are discussed.

Non-Homogeneous Conduction In Giant Axons Of The Nerve Cord Of Periplaneta Americana

1969 ◽  
Vol 50 (3) ◽  
pp. 635-649
Author(s):  
I. PARNAS ◽  
M. E. SPIRA ◽  
R. WERMAN ◽  
F. BERGMANN
Keyword(s):  
Nerve Cord ◽  
Periplaneta Americana ◽  
Repetitive Stimulation ◽  
Low Doses ◽  
Thoracic Region ◽  
Safety Factors ◽  
Suboesophageal Ganglion ◽  
Giant Axons ◽  
Physiological Conditions ◽  
Stimulation Of

Studies with intracellular electrodes show that the abdominal giant axons of the cockroach give ascending responses to stimulation of cercal nerves and descending responses to stimulation of S0-T1 connectives. 2. In the thoracic region one or more areas of low safety factors occur for descending conduction. 3. These areas, which are considered not to be synapses, are blocked by low doses of nicotine (2-5 µg./ml.) fatigued by repetitive stimulation and show conduction delays of 0·6-0·7 msec. 4. It is concluded that the abdominal giant axons extend continuously from A6 to suboesophageal ganglion. The possibility of bi-directional conduction under physiological conditions is discussed.

scholarly journals Histological and electrophysiological Studies On The Giant Axons Of The Cockroach Periplaneta Americana

1969 ◽  
Vol 50 (3) ◽  
pp. 629-634
Author(s):  
M. E. SPIRA ◽  
I. PARNAS ◽  
F. BERGMANN
Keyword(s):  
Nerve Cord ◽  
Periplaneta Americana ◽  
American Cockroach ◽  
Giant Axons ◽  
Electrophysiological Studies ◽  
Nerve Cords

1. Nerve cords of the American cockroach were cut between the 5th and 6th abdominal ganglia. 2. All giant axons degenerated in the abdominal regions and were present but collapsed in the thoracic connectives. 3. Unilateral lesions permitted identification of ventral giant axons all along the nerve cord.

Visual and Multimodal Interneurones in the Ventral Nerve Cord of the Cockroach, Periplaneta Americana

1973 ◽  
Vol 59 (3) ◽  
pp. 675-696
Author(s):  
R. J. COOTER
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Tactile Stimulation ◽  
Periplaneta Americana ◽  
Compound Eye ◽  
Visual Stimulation ◽  
Contralateral Stimulation ◽  
Thoracic Nerve ◽  
General Properties ◽  
Stimulation Of

1. Visual and multimodal units were recorded from the thoracic nerve cord of the cockroach, Periplaneta americana, using glass microelectrodes. 2. Compound-eye units could be classified as ON-, OFF- or ON-OFF-units according to their response to visual stimulation. Some were multimodal, firing to both visual and tactile stimulation of the antennae. 3. Although some units were found to be either fired by ipsilateral or by contralateral stimulation only, others were fired by both types of stimulation, often in different ways. 4. Ocellar units were invariably OFF-units, mainly phasic, but one type showed tonic dark-firing in addition to the phasic OFF-burst. 5. The general properties of cockroach visual units are discussed and compared with those reported by other workers for different insects.

Control of Salivation in the Blowfly Calliphora

1978 ◽  
Vol 75 (1) ◽  
pp. 189-201
Author(s):  
CHRISTINA M. HANSEN BAY
Keyword(s):  
Nerve Cord ◽  
Digestive Enzymes ◽  
Ventral Nerve Cord ◽  
Fluid Secretion ◽  
Thoracic Ganglion ◽  
Salivary Duct ◽  
Thoracic Nerve ◽  
Sugar Receptors ◽  
Stimulation Of

1. A technique has been developed for collecting saliva from the salivary duct of flies during feeding. 2. In newly emerged flies salivation is evoked by stimulation of the labellar taste papillae by crystalline sugar, by sugar in solution and by water. Only sugars which excite the sugar receptors are effective. 3. In flies which have previously fed, solid sucrose or meat induce regurgitation of the crop contents, or salivation if the crop is empty. Sucrose in solution provokes neither reaction. 4. Saliva always contains digestive enzymes, even if the ingested food requires no digestion. 5. Blood taken from salivating flies stimulates fluid secretion from isolated glands, whereas blood taken from non-salivating flies is ineffective. 6. Section of the cephalo-thoracic nerve cord abolishes salivation in response to feeding. Section of the ventral nerve cord posterior to the thoracic ganglion, or removal of the abdomen, severely reduces but does not abolish the salivatory response. 7. Saliva secreted by mature flies contains 75 mM-Cl− whereas saliva secreted during the first meal after emergence has a higher Cl− concentration (about 165 mM-Cl−) which gradually declines during the first meal.

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.

Sign in / Sign up

Export Citation Format

Share Document