The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish

1972 ◽  
Vol 30 ◽  
pp. 170-171
Author(s):  
Charles A. Stirling
Keyword(s):  
Synaptic Vesicles ◽  
Procambarus Clarkii ◽  
Synaptic Contact ◽  
Giant Fiber ◽  
Synaptic Junctions

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.

Neurosecretory innervation of the pituitary of the eels Anguilla and Conger I. The structure and ultrastructure of the neuro-intermediate lobe under normal and experimental conditions

1966 ◽  
Vol 250 (768) ◽  
pp. 311-327 ◽  
Keyword(s):  
Sea Water ◽  
Synaptic Contact ◽  
Type A ◽  
White Background ◽  
Pars Intermedia ◽  
Intermediate Lobe ◽  
Experimental Conditions ◽  
Synaptic Junctions ◽  
Neurosecretory Fibre ◽  
Structure And Ultrastructure

Three kinds of neurosecretory fibre (Types A 1 , A 2 and B) are present in the neural component of the neuro-intermediate lobe of the eel pituitary. These fibres do not in the main make any direct contact with the pars intermedia cells, but they are separated by only a narrow extravascular channel, into which both elements discharge their products. Type A neurosecretory fibres do, however, make direct synaptic contact with pituicytes which resemble ependyma and surround finger-like extensions of the infundibular recess. That these contacts are functional is indicated by the fact that their frequency is related to changes in the environment. When eels are placed on an illuminated white background the synaptic junctions between Type A 2 neurosecretory fibres and pituicytes are very frequent. Similar synaptic junctions between A 1 fibres and pituicytes were only found in animals which had been recently transferred from fresh water to sea water. A possibility that the pituicytes play some part in a feed-back from the pituitary to the hypothalamus is discussed.

scholarly journals THE SMALL PYRAMIDAL NEURON OF THE RAT CEREBRAL CORTEX

1968 ◽  
Vol 39 (3) ◽  
pp. 604-619 ◽  
Author(s):  
Alan Peters ◽  
Charmian C. Proskauer ◽  
Ita R. Kaiserman-Abramof
Keyword(s):  
Cerebral Cortex ◽  
Dendritic Spines ◽  
Pyramidal Neuron ◽  
Synaptic Vesicles ◽  
Initial Segment ◽  
Axon Terminals ◽  
Axon Hillock ◽  
Synaptic Junctions ◽  
Cytological Features ◽  
Synaptic Complexes

The axon of the pyramidal neuron in the cerebral cortex arises either directly from the perikaryon or as a branch from a basal dendrite. When it arises from the perikaryon, an axon hillock is present. The hillock is a region in which there is a transition between the cytological features of the perikaryon and those of the initial segment of the axon. Thus, in the hillock there is a diminution in the number of ribosomes and a beginning of the fasciculation of microtubules that characterize the initial segment. Not all of the microtubules entering the hillock from the perikaryon continue into the initial segment. Distally, the axon hillock ends where the dense undercoating of the plasma membrane of the initial segment commences. Dense material also appears in the extracellular space surrounding the initial segment. The initial segment of the pyramidal cell axon contains a cisternal organelle consisting of stacks of flattened cisternae alternating with plates of dense granular material. These cisternal organelles resemble the spine apparatuses that occur in the dendritic spines of this same neuron. Axo-axonal synapses are formed between the initial segment and surrounding axon terminals. The axon terminals contain clear synaptic vesicles and, at the synaptic junctions, both synaptic complexes and puncta adhaerentia are present.

Nerve Cells and Fibers in the Optic Lobe Cortex of Octopus

1971 ◽  
Vol 29 ◽  
pp. 238-239 ◽  
Author(s):  
Norman M. Case ◽  
E. G. Gray
Keyword(s):  
Optic Nerve ◽  
Synaptic Vesicles ◽  
Granular Layer ◽  
Optic Lobe ◽  
Synaptic Contact ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Nerve Fibers ◽  
Fiber Types ◽  
Basement Layer

Montages of electron micrographs from the outer portion of the cortex of the optic lobe of Octopus are shown. Sheets of dark cytoplasm which originate from glial cells in the outer granular layer form a basement layer separating the outer granular layer from the deeper plexiform layer.Optic nerve fibers from the retina entering the optic lobe around its periphery must pass between the amacrine cells composing the bulk of the outer granular layer. Here they are the darker of the two fiber types that can be identified. Passing through the basement layer they expand into large “carrot” shaped terminal endings easily identified by their dark appearance caused by the extremely high content of synaptic vesicles they contain.Fibers in the neuropil press tightly against and indent the “carrots” and occasionally make synaptic contact with them. Some fibers penetrate deeply into the “carrots” where they branch and terminate in grape-like clusters that show many synaptic contacts with the enveloping bag.

Expression of synaptotagmin in Drosophila reveals transport and localization of synaptic vesicles to the synapse

Development ◽  
1993 ◽  
Vol 118 (4) ◽  
pp. 1077-1088 ◽  
Author(s):  
J.T. Littleton ◽  
H.J. Bellen ◽  
M.S. Perin
Keyword(s):  
Nervous System ◽  
Synaptic Vesicle ◽  
Synaptic Vesicles ◽  
Synapse Formation ◽  
Neuromuscular Junctions ◽  
Synaptic Contact ◽  
Immunocytochemical Staining ◽  
Intense Staining ◽  
General Role ◽  
Contact Sites

Synaptotagmin is a synaptic vesicle-specific integral membrane protein that has been suggested to play a key role in synaptic vesicle docking and fusion. By monitoring Synaptotagmin's cellular and subcellular distribution during development, it is possible to study synaptic vesicle localization and transport, and synapse formation. We have initiated the study of Synaptotagmin's expression during Drosophila neurogenesis in order to follow synaptic vesicle movement prior to and during synapse formation, as well as to localize synaptic sites in Drosophila. In situ hybridizations to whole-mount embryos show that synaptotagmin (syt) message is present in the cell bodies of all peripheral nervous system neurons and many, if not all, central nervous system neurons during neurite outgrowth and synapse formation, and in mature neurons. Immunocytochemical staining with antisera specific to Synaptotagmin indicates that the protein is present at all stages of the Drosophila life cycle following germ band retraction. In embryos, Synaptotagmin is only transiently localized to the cell body of neurons and is transported rapidly along axons during axonogenesis. After synapse formation, Synaptotagmin accumulates in a punctate pattern at all identifiable synaptic contact sites, suggesting a general role for Synaptotagmin in synapse function. In embryos and larvae, the most intense staining is found along two broad longitudinal tracts on the dorsal side of the ventral nerve cord and the brain, and at neuromuscular junctions in the periphery. In the adult head, Synaptotagmin localizes the discrete regions of the neurophil where synapses are predicted to occur. These data indicate that synaptic vesicles are present in axons before synapse formation, and become restricted to synaptic contact sites after synapses are formed. Since a similar expression pattern of Synaptotagmin has been reported in mammals, we propose that the function of Synaptotagmin and the mechanisms governing localization of the synaptic vesicle before and after synapse formation are conserved in invertebrate and vertebrate species. The ability to mark synapses in Drosophila should facilitate the study of synapse formation and function, providing a new tool to dissect the molecular mechanisms underlying these processes.

scholarly journals The fine structure of a rectifying electrotonic synapse.

1978 ◽  
Vol 79 (3) ◽  
pp. 764-773 ◽  
Author(s):  
R B Hanna ◽  
J S Keeter ◽  
G D Pappas
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Ventral Nerve Cord ◽  
Procambarus Clarkii ◽  
Giant Axon ◽  
Morphological Evidence ◽  
Giant Fiber ◽  
Ordered Array ◽  
20 Nm ◽  
Tubular Endoplasmic Reticulum

The synapses between the lateral giant axon and the giant motor axon found in the abdominal ganglia of the ventral nerve cord of the crayfish Procambarus clarkii are electronic. The junctional membrane rectifies, favoring impulse transmission from lateral giant fiber to giant motor fiber. This rectifying electronic junction consists of closely apposed membranes indistinguishable from ordinary arthropod gap junctions. The apposed membranes contain intramembrane particles that are approximately 12.5 nm in width. These particles have a central depression and are arranged in a loosely ordered array with a center-to-center spacing of about 20 nm. The only obvious morphological evidence of asymmetry is the presence of vesicles (about 80 nm in diameter) in the cytoplasm adjacent to the junctional region of the presynaptic lateral giant fiber. Vesicles are not present in the adjacent cytoplasm of the postsynaptic giant motor fiber; however, mitochondria and smooth tubular endoplasmic reticulum are more frequent in the cytoplasm of the giant motor fiber.

Synaptic restructuring during long-term facilitation at the crayfish neuromuscular junction

1989 ◽  
Vol 67 (2) ◽  
pp. 167-171 ◽  
Author(s):  
J. M. Wojtowicz ◽  
L. Marin ◽  
H. L. Atwood
Keyword(s):  
Procambarus Clarkii ◽  
Synaptic Contact ◽  
Release Site ◽  
Motor Axon ◽  
Presynaptic Membrane ◽  
Active Zones ◽  
Long Term Facilitation ◽  
Crayfish Neuromuscular Junction ◽  
Stimulation Of

Long-term facilitation was induced by 20-Hz stimulation of the motor axon innervating the opener muscle of the crayfish, Procambarus clarkii. Excitatory postsynaptic potentials remained potentiated for several hours after stimulation. Structural correlates of potentiation were sought. Nerve terminals of the motor axon were fixed for electron microscopy in unstimulated preparations (controls), and during and after 20-Hz stimulation. Synapses were reconstructed from micrographs obtained from serial sections. Synaptic contact area and the number of vesicles at the presynaptic membrane did not change after 20-Hz stimulation, but the latter decreased during stimulation. Presynaptic dense bars ("active zones") decreased in number during and increased after stimulation, while perforated synapses increased after stimulation. Modification of presynaptic structures occurs rapidly and may be linked to long-lasting changes in quantal content of transmission.Key words: facilitation, plasticity, release site, synaptic vesicle, transmitter release.

Synaptic organization of the frog retina: an electron microscopic analysis comparing the retinas of frogs and primates

1968 ◽  
Vol 170 (1019) ◽  
pp. 205-228 ◽  
Keyword(s):  
Synaptic Vesicles ◽  
Synaptic Contact ◽  
Plexiform Layer ◽  
Amacrine Cells ◽  
Outer Plexiform Layer ◽  
Inner Plexiform Layer ◽  
Synaptic Organization ◽  
Synaptic Contacts ◽  
Frog Retina ◽  
Cell Processes

The synaptic contacts in the inner and outer plexiform layers of the frog retina have been identified and studied by electron microscopy. In the inner plexiform layer, two types of synaptic contact were recognized. One type, believed to be the synaptic contact of the bipolar terminals, is characterized by a synaptic ribbon in the presynaptic cytoplasm. At such ribbon contacts, there are ordinarily two postsynaptic elements, both of which usually contain numerous synaptic vesicles and appear morphologically identical. The second type of synaptic contact in the inner plexiform layer has a more conventional morpho­logy and is observed very much more frequently than are the ribbon contacts. It is characterized by a dense aggregation of synaptic vesicles clustered close to the presynaptic membrane and is thought to be the synaptic contact of the amacrine processes. The conventional synapses are presynaptic to ribbon-containing processes, ganglion cell dendrites, and other amacrine cell processes. Reciprocal contacts between processes making ribbon synapses, and processes making conventional synapses are often observed. Serial synapses between morphologically identical processes, presumably amacrine processes, are frequently seen; and up to four synapses in series between five adjacent processes have been observed. These findings suggest that in the inner plexiform layer of the frog: (1) bipolar terminals synapse primarily with amacrine processes; (2) amacrine processes synapse extensively with the processes of other amacrine cells; and (3) ganglion cells are driven primarily by the amacrine cells. In the outer plexiform layer, processes penetrate into invaginations in the bases of the receptor terminals and lie in close proximity to the synaptic ribbons of the terminals, where the processes presumably receive synaptic input from the receptors. Elsewhere in the outer plexiform layer, knob-like processes, probably from horizontal cells, make conventional synaptic contacts with other horizontal cell processes and probably with bipolar dendrites.

A Note on Synaptic Structure of the Retina of Octopus Vulgaris

1970 ◽  
Vol 7 (1) ◽  
pp. 203-215
Author(s):  
E. G. GRAY
Keyword(s):  
Electron Microscopy ◽  
Synaptic Vesicles ◽  
Synaptic Contact ◽  
Octopus Vulgaris ◽  
Synaptic Membrane ◽  
Visual Cell ◽  
Regular Pattern ◽  
Synaptic Structure ◽  
Optic Axons

Electron microscopy of the octopus retina shows that both types of synapse (formed by the visual cell collaterals and the efferents respectively) have synaptic membrane specializations with associated aggregations of synaptic vesicles--features usually regarded as indicative of synaptic contact. These have hitherto been considered as absent from the octopus retina. Other details of the retinal synapses are described and in addition the grouped microtubules in the initial portions of the optic axons are seen to have in association a regular pattern of micro-filaments.

Learning by Tension

2007 ◽  
Author(s):  
Shengyuan Yang ◽  
Scott Siechen ◽  
Jie Sun ◽  
Akira Chiba ◽  
Taher Saif
Keyword(s):  
Nervous System ◽  
Synaptic Vesicles ◽  
Fruit Fly ◽  
Basic Mechanism ◽  
Drosophila Embryo ◽  
Mems Sensors ◽  
Mechanical Tension ◽  
Memory And Learning ◽  
Synaptic Junctions ◽  
Signaling Process

Memory and learning in animals is mediated by neurotransmission at the synaptic junctions (end point of axons). Neurotransmitters are carried by synaptic vesicles which cluster at the junctions, ready to be dispatched for transmission. The more a synapse is used, higher is the clustering, and higher is the neurotransmission efficiency (plasticity), i.e., the junction “remembers” its use in the near past, and modifies accordingly. This usage dependent plasticity offers the basic mechanism of memory and learning. A central dogma in neuroscience is that, clustering is the result of a complex biochemical signaling process. We show, using MEMS sensors and fruit fly (Drosophila) embryo nervous system, that mechanical tension in axons is essential for clustering. Without tension, clustering disappears, but reappears with application of tension. Nature maintains a rest tension of 1nN in axons of Drosophila for learning and memory.

Sign in / Sign up

Export Citation Format

Share Document