CNS microstructure in the wandering wolf spider Arctosa kwangreungensis (Araneae: Lycosidae)

The supraesophageal ganglion of the wolf spider Arctosa kwangreungensis is made up of a protocerebral and tritocerebral ganglion, whereas the subesophageal ganglionic mass is composed of a single pair of pedipalpal ganglia, four pairs of appendage ganglia, and a fused mass of abdominal neuromeres. In the supraesophageal ganglion, complex neuropile masses are located in the protocerebrum which include optic ganglia, the mushroom bodies, and the central body. Characteristically, the only nerves arising from the protocerebrum are the optic nerves, and the neuropiles of the principal eyes are the most thick and abundant in this wandering spider. The central body which is recognized as an important association center is isolated at the posterior of the protocerebrum and appears as a complex of highly condensed neurons. These cells give off fine parallel bundles of axons arranged in the mushroom bodies. The subesophageal nerve mass can be divided into two main tracts on the basis of direction of the neuropiles. The dorsal tracts are contributed to from the motor or interneurons of each ganglion, whereas the ventral tracts are from incoming sensory axons.     

Hyalomma dromedarii (Acari: Ixodoidea: Ixodidae): Central and peripheral nervous system anatomy

TheHyalommadromedarii central nervous system, the synganglion, is an integrated nerve mass concentrated around the esophagus and formed by fusion of a small anterodorsal supraesophageal part an a large posteroventral subesophageal part. The supraesophageal part consists of the protocerebrum including a pair of optic ganglia, a pair of cheliceral ganglia, a pair of pedipalpal ganglia, and the stomodeal pons. The subesophageal part includes four paired pedal ganglia and the complex opisthosomatic ganglion. The peripheral nervous system includes the following pairs of nerves: optic, cheliceral, pedipalpal, primary and accessory (histologically traced); also unpaired pharyngeal and recurrent nerves, four pairs of pedal nerve trunks, each with a hemal branch, and two pairs of opisthosomatic nerves. Each peripheral nerve is traced distally to the innervation site. The salivary glands are innervated anteriorly by branches of the pedipalpal nerve and medially by branches of the hemal nerves associated with the third pedal nerves.Reprint request should be sent to: Medical Zoology Department, NAMRU-3, Fleet Post Office, New York 09527, U.S.A.     

The ultrastructure of the cardiac ganglion of the desert scorpion,Paruroctonus mesaensis (Scorpionida: Vaejovidae)

Light and electron microscopy of the pacemaker ganglion of the scorpion heart indicate that it is about 15 mm long and 50 μm in diameter and extends along the dorsal midline of the heart. The largest cell bodies (30–45 μm in diameter) occur in clusters along the length of the ganglion. The ganglion appears to be innervated with fibers from the subesophageal and first three abdominal ganglia. The cardiac ganglion is surrounded by a neurilemma and a membranous sheath. The latter is apparently derived from connective tissue cells seen outside the ganglion. Nerve fibers other than those in the neuropil areas are usually surrounded by membrane and cytoplasm of glial cells. Often there are several layers of glial membrane, forming a loose myelin. The cardiac nerves to the heart muscle are also surrounded by a neurilemma, and the axons are surrounded by glia. The motor nerves contain lucent vesicles 60–100 nm and opaque granules 120–180 nm in diameter. In the cardiac ganglion, some nerve cell bodies have complex invaginations of glial processes forming a peripheral trophospongium. In the neuropil areas, nerve cell processes are often in close apposition. The septilaminar configuration typical of gap junctions is common, with gap distances of 1–4 nm. In tissues stained with lanthanum phosphate during fixation, we found gaps with unstained connections (1–2 nm diameter) between nerve-nerve and glial-nerve cell processes. Annular or double-membrane vesicles in various stages of formation were also seen in some nerve fibers in ganglia stained with lanthanum phosphate. Nerve endings with electron-lucent vesicles 40–60 nm in diameter are abundant in the cardiac ganglion, suggesting that these contain the excitatory transmitter of intrinsic neurons of the ganglion. Less abundant are fibers with membrane-limited opaque granules, circular or oblong in shape and as much as 330 nm in their longest dimension. Also seen were some nerve endings with both vesicles and granules.     

The distribution of several amino acids in specific ganglia and nerve bundles of the lobster

Using the technique of measuring DNP-amino acid methyl esters by gas-liquid chromatography, the distribution of alanine, proline, glycine, GABA, glutamate and aspartate was determined in individual ganglia and the associated nerve bundles between these ganglia after isolation from the nervous system of the lobster, Homarus americanus. The brain or supraesophageal ganglion (27.2 mg) and the next 5 thoracic ganglia (varying from 24 to 10 mg in a rostral–caudal direction) as well as the nerve bundles connecting these ganglia were used. GABA and aspartate values varied the most among the individual ganglia; highest values were found in the second and third thoracic ganglia. The levels of alanine, proline, glycine and glutamate varied very little from ganglion to ganglion; however, the values for these amino acids did exhibit some variability among the individual connectives. The highest value for each was in the nerve bundle between the first and second thoracic ganglion. Glycine was present at the highest level of any of the amino acids whereas GABA was at the lowest level in the individual structures assayed.     

Isolation of an insect circadian clock

Summary Under constant conditions the compound eyes of the ground beetleAnthia sexguttata exhibit sensitivity changes in a very clear circadian rhythm. Usually the rhythms in both eyes in constant darkness are mutually coupled. After transection of the optic tract between the lobula and the supraesophageal ganglion the circadian rhythms of the two eyes continue without interruption, but coupling between them is abolished. Even if the entire supraesophageal ganglion is removed, leaving the optic ganglia intact, the circadian rhythms in the eyes continue without interruption independently. But the rhythm is abolished if the region of the lobula is damaged.The experiments show thatAnthia has circadian pacemakers in the left and right optic ganglia in or close to the lobula. These pacemakers can function independently from the rest of the brain and control circadian rhythms of physiological events.Supported by the Deutsche Forschungsgemeinschaft, Sonderforschungsbereich 45 Vergleichende Neurobiologie des Verhaltens E1     

Immunoreactivity of Glutamic Acid Decarboxylase (GAD) Isoforms in the Central Nervous System of the Barn Spider,Araneus cavaticus

The γ‐aminobutyric acid (GABA) has long been considered as an inhibitory neurotransmitter in the central nervous system (CNS) of both vertebrates and arthropods. Since the glutamic acid decarboxylase (GAD) has a restricted tissue distribution and catalyzes the conversion of L‐glutamate to GABA, immunoreactivity of GAD isoforms can reveal distribution of GABAergic neurons in the CNS. In the CNS of the spider Araneus cavaticus, immunoreactivity of GAD isoforms can be detected in the optic lobes including neurons and neuropiles of the supraesophageal ganglia. Strong GAD‐like immunoreactive cell bodies are concentrated in two bilaterally symmetric cell clusters of the protocerebrum. Some intrinsic cell bodies near the central body also show strong immunoreactivity. However, the intrinsic nerve masses and some of the longitudinal and transverse tracts within the supraesophageal ganglion are only lightly labelled, and the fibers transverse the hemisphere and the central fibrous masses are not labelled. Among the three basic types of cell bodies surrounding the central body, several clusters of the Type‐C cells show strong GAD‐like immunoreactivity, however both of the Type‐A and Type‐B cells are not labelled at all.     

Cytophysiological study of neurosecretory and pheromonal influences on sexual development in Ophryotrocha puerilis (Polychaeta,Dorvilleidae)

Summary

Prominent secretory nerve endings are found at the posterior margin of the supraesophageal ganglion in the protandric polychaete, Ophryotrocha puerilis. Solitary juveniles developing as primary males, and then as females, accumulate neurosecretory material in the nerve endings which thereby swell and become filled with granules. Females maintained in mass culture have similar terminals, whereas in secondary males (males which had been females before), these axon terminals are very small and contain no material. When such males are isolated, they accumulate neurosecretory material within the nerve endings and become females. When formerly isolated females are put together, their stores of neurosecretory material are rapidly discharged. Subsequently they lay egg masses and switch to the male state. These effects are mediated by a pheromone released during social contact of formerly isolated females. The complexity of the relationship between neurosecretory activity and sexual state is indicated by the situation in animals maintained in pairs, when both male and female partners have swollen nerve endings packed with secretory material.     

Specialized brain regions and sensory inputs that control locomotion in leeches

Locomotor systems are often controlled by specialized cephalic neurons and undergo modulation by sensory inputs. In many species, dedicated brain regions initiate and maintain behavior and set the duration and frequency of the locomotor episode. In the leech, removing the entire head brain enhances swimming, but the individual roles of its components, the supra- and subesophageal ganglia, in the control of locomotion are unknown. Here we describe the influence of these two structures and that of the tail brain on rhythmic swimming in isolated nerve cord preparations and in nearly intact leeches suspended in an aqueous, “swim-enhancing” environment. We found that, in isolated preparations, swim episode duration and swim burst frequency are greatly increased when the supraesophageal ganglion is removed, but the subesophageal ganglion is intact. The prolonged swim durations observed with the anterior-most ganglion removed were abolished by removal of the tail ganglion. Experiments on the nearly intact leeches show that, in these preparations, the subesophageal ganglion acts to decrease cycle period but, unexpectedly, also decreases swim duration. These results suggest that the supraesophageal ganglion is the primary structure that constrains leech swimming; however, the control of swim duration in the leech is complex, especially in the intact animal.     

Fine Structural Analysis of the Central Nervous System in the Spider, Achaearanea tepidariorum (Theridiidae: Araneae)

ABSTRACT Central nervous system (CNS) of arachnids is still mysterious and has a rich unexplored field compare to what is known in insects or crustaceans. The CNS of the spider, Achaearanea tepidariorum, consists of a dorsal brain or supraesophageal ganglion and circumesophageal connectives joining it to the subesophageal mass. As the segmentation of the arachnid brain is still under discussion, we classify the brain as a protocerebral and tritocerebral ganglion depending on the evidences which generally accepted. The subesophageal nerve mass underneath the brain is the foremost part of the ventral nerve cord. All of this nerve mass is totally fused together, and forming subesophageal ganglia in this spider. In the brain, the nerve cells are packed in the frontal, dorsal and lateral areas, but are not absent from the posterior and ventral regions. In addition, the nerve cells of the subesophageal and abdominal ganglia are only restricted to the ventral and ventolateral regions. The CNS of the spider, Achaearanea tepidariorum is similar in feature to the Family Araneidae.     

Anatomy of synganglia, including their neurosecretory regions, in unfed, virgin female Ixodes scapularis say (Acari: Ixodidae).

The central nervous system of Ixodes scapularis is fused into a single compact synganglion. The esophagus runs through the synganglion and divides it into supraesophageal and subesophageal parts. The supraesophageal portion contains a single protocerebrum with four pairs of glomeruli, paired optic lobes and cheliceral ganglia, and a single stomodeal bridge. The subesophageal portion contains a centrally located network of commissures and connectives, a pair of palpal ganglia, paired olfactory lobes of the first pedal ganglia, four pairs of pedal ganglia, and a single opisthosomal ganglion. A retrocerebral organ complex (ROC) in close vicinity of the digestive tract, as described in some other tick species, apparently is lacking. Perhaps the function of the ROC is performed by the paired, large, ganglion-like bodies that lie anterolaterad to the cheliceral ganglia. The rind, which is formed from the neuronal somata and glial cells, surrounds the central fibrous core or neuropile. Neurosecretory cells (NSC) are distinct among rind cells due to their large size and concentration of cytoplasmic neurosecretions. NSC are present throughout the synganglion, although the subesophageal portion contains larger groups of these cells. Histological serial sections, stained with Meola's (Trans Am Microsc Soc 89:66-71, '70) paraldehyde fuchsin (PAF) procedure revealed 24 PAF-stained, putative neurosecretory regions in the synganglion of virgin, unfed females. All of these regions appear to be connected and associated with the nearest ganglion and are correspondingly named. Eighteen PAF-positive regions occur in the synganglion. In addition, PAF-negative (green-stained) cells occupy 6 distinct regions in the synganglion of unfed, unmated females.     

Topographic anatomy of ascending and descending neurons of the supraesophageal,meso- and metathoracic ganglia in paleo- and neopterous insects

Topographic anatomy of ascending (AN) and descending (DN) neurons of the supraesophageal and thoracic ganglia in the nervous system of winged insects (Pterygota), representatives of the infraclasses Palaeoptera (Odonata, Aeschna grandis, dragonfly) and Neoptera (Blattoptera, Periplaneta americana, cockroach), was studied. These insects differ in ecological niches, lifestyles, sets of behavioral complexes, levels of locomotor system development, evolutionary age and systematic position. Cell bodies and processes of ANs and DNs were stained with nickel chloride (NiCl₂), and their topography was studied on total preparations of the supraesophageal and thoracic ganglia. Unlike cockroaches, the dragonfly protocerebrum was found to contain DNs sending their processes to ocelli. Dragonfly DN processes exhibit a specific branching pattern in thoracic ganglia, with collaterals coming off both ipsi- and contralaterally. In cockroaches, collaterals of DN processes come off ipsilaterally. The AN cell bodies in dragonfly meso- and metathoracic ganglia lie both ipsi- and contralaterally relative to the ascending process, whereas in cockroaches most of the AN cell bodies in the same ganglia are located contralaterally. Substantial differences in the distrubution of DNs and ANs in insects with different manners of locomotion appear to reflect different degrees of control the supraesophageal ganglion exerts over the activity of segmental centers. This does not seem to be related to the evolutionary age of insects or their systematic position. Probably, different degrees of control over locomotion depend on the way of food acquisition: catching prey in the air in “paleopterous” dragonflies versus maneuverable walking or running over a solid substrate in “neopterous” cockroaches.     

PHOSPHOLIPIDS IN THE NERVOUS SYSTEM OF MOLLUSCS

Abstract The phospholipid composition of nervous ganglia of the bivalve Unio crassa , the gastropod Helix pomatia and the cephalopods Octopus sp. and Ommastrephes sloanei pacificus have been investigated.
The ganglia of cephalopods contain considerably more phospholipids than do gastropod and bivalve ganglia. Especially rich in phospholipids are the optic ganglion of the squid Ommastrephes and the cerebral ganglion of Octopus , where their content is of the same order as in the brain of teleosts and amphibia.
In the ganglia of the lower molluscs, the bivalve and the gastropod, no sphingomyelin nor X-phospholipid could be detected.
No sphingomyelin nor X-phospholipid were found in the optic ganglion of Octopus , whereas in its cerebral ganglion sphingomyelin but no X-phospholipid was present.
In both the optic and the cerebral ganglia of the squid Ommastrephes both sphingomyelin and X-phospholipid were found.     

淡水蜗牛视觉系统的输入与输出通路(英文)

通过神经生物素在视神经上的逆行性传输对淡水蜗牛(Planorbarius corneus)视网膜及中央神经节的输入、输出神经元进行标记。由于没有发现突触联系,所以至少一部分光感受细胞的轴突可被视为直接参与形成视神经。这些神经元的轴突进入大脑神经节形成密集的细传入神经纤维束-视神经堆。传出神经元则存在于除颊部以外的所有神经节。一些上行轴突在大脑神经节处分叉,通过脑-脑联合,到达对侧眼并在眼杯处形成分枝。部分传出神经元的轴突也投射于不同的外周神经,如:n.n.intestinalis,pallialis dexter,pallialis sinister internus et externus。五羟色胺能纤维和FMRF-酰胺能纤维均存在于视神经上,且这些纤维隶属于只投射在同侧眼的中央神经元。它们形成了位于眼杯处的丰富曲张结构及视网膜核心层,并且可能有助于调节视网膜对光的敏感性。     

Biogenic monoamines in Hirudo medicinalis

Summary The distribution of certain catecholamines and indoleamines in the ventral nerve cord and the body segments of the medical leech, Hirudo medicinalis, was studied with the fluorescence microscope technique of Falck and Hillarp, with microspectrofluorometry, and with chemical determinations of the amines. The six cells of the segmental ganglia previously shown to be chromaffin were found to contain an amine, most probably 5-hydroxytryptamine. In the two giant cells, the amine was found on the surface of coarse intracellular granules, lying mainly at the cell membrane, and at the nucleus. The two giant cells send their axons to the body muscles, which thus seem to have a 5-hydroxytryptaminergic innervation. The four smaller amine-containing cells of the segmental ganglia send their axons to the neuropil of the ganglion.The only cell type found to contain a catecholamine (probably noradrenaline) was situated in the anterior segmental nerve in the cell cluster anterior of the nephridial duct, one cell in each nerve. The axon of this cell terminates in two or more segmental ganglia; thus these neurons seem to be afferent.This work was supported by grants from the Swedish Natural Science Research Council (project no. 99-35) and the Swedish Medical Research Council (projects no. B 68-12 X-712-03 B and B 68-14 X-56-04 B).     

Morphological and physiological properties of the giant interneuron of the hermit crab (Pagurus pollicaris)

The physiological and morphological properties of the giant interneurons in the hermit crab Pagurus pollicaris are described. The cell bodies are located anteriorly in the supraesophageal ganglion, close to the mid-line. Each cell sends a neurite posteriorly and then laterally, so that they cross over in the center of the ganglion. Each axon then branches: one branch runs laterally while the other travels posteriorly and leaves the ganglion in the circumesophageal connective on the side contralateral to the cell body. The giant axons travel in the circumesophageal connectives and through the thoracic and abdominal ganglia without branching. Each giant axon makes synaptic contact with its ipsilateral giant abdominal flexor motor neuron and with a second flexor motor neuron that has its axon in the contralateral third root. In the supraesophageal ganglion there is a bidirectional synapse between the two giant interneurons. Intracellular recordings from the giant axons show that there is a delay of 0.5 to 0.75 ms that cannot be accounted for by spike propagation along the axons, and may be accounted for by a chemical synapse between the giant interneurons.     

Embryonic cell lineages in the nervous system of the Glossiphoniid leech Helobdella triserialis

The lines of descent of cells of the nervous system of the leech Helobdella triserialis have been ascertained by injection of horseradish peroxidase (HRP) as a tracer into identified cells of early embryos. Such experiments show that the nervous system of the leech has several discrete embryological origins. Some of the neurons on one side of each of the segmental ganglia derive from a single cell, the ipsilateral N ectoteloblast. Other neurons derive from a different precursor cell, the ipsilateral OPQ cell that gives rise to the O, P, and Q ectoteloblasts. The positions within the ganglion of neuronal populations derived from each of these sources are relatively invariant from segment to segment and from specimen to specimen. Other nerve cord cells derive from the mesoteloblast M; of these four per segment appear to be the precursors of the muscle cells of the connective. The A, B, or C macromeres contribute cells to the supraesophageal ganglion. In preparations in which an N ectoteloblast was injected with HRP after production of its bandlet of n stem cells had begun, the boundary between unstained (rostral) and stained (caudal) tissues can fall within a ganglion or between ganglia. This suggests that each hemiganglion contains the descendants of more than one, and probably two, n stem cells.     

New vistas on the initiation and maintenance of insect motor behaviors revealed by specific lesions of the head ganglia

In insects, thoracic pattern generators are modulated by the two head ganglia, the supraesophageal ganglion (brain) and the subesophageal ganglion, which act as higher-order neuronal centers. To explore the contribution of each head ganglion to the initiation and maintenance of specific motor behaviors in cockroaches (Periplaneta americana), we performed specific lesions to remove descending inputs from either the brain or the subesophageal ganglion or both, and quantified the behavioral outcome with a battery of motor tasks. We show that ‘emergency’ behaviors, such as escape, flight, swimming or righting, are initiated at the thoracic level independently of descending inputs from the head ganglia. Yet, the head ganglia play a major role in maintaining these reflexively initiated behaviors. By separately removing each of the two head ganglia, we show that the brain excites flight behavior and inhibits walking-related behaviors, whereas the subesophageal ganglion exerts the opposite effects. Thus, control over specific motor behaviors in cockroaches is anatomically and functionally compartmentalized. We propose a comprehensive model in which the relative permissive versus inhibitory inputs descending from the two head ganglia, combined with thoracic afferent sensory inputs, select a specific thoracic motor pattern while preventing the others.     

5-HYDROXYTRYPTAMINE, HISTAMINE AND N-ACETYLHISTAMINE IN THE NERVOUS SYSTEM OF DOSIDICUS GIGAS

Abstract— The optic ganglia, cerebral ganglia and mantle nerve of the squid Dosidicus gigas were examined for possible amines. Histamine was detected in all three tissues. The optic ganglia were also found to contain 5-HT and N -acetylhistamine, an infrequently found derivative of histamine.     

Neuronal pathways of three neurosecretory cells from the lateral lobes in Helisoma (Mollusca): innervation of the dorsal body

The neurite distribution of three large neurosecretory cells, namely one canopy cell and two lateral-lobe cells from each lateral lobe of the cerebral ganglia in Helisoma duryi were studied by thick and thin plastic serial sections. These cells from only the right lateral lobe innervate the dorsal body. Neurites from the canopy cell innervate the cell-bodies whereas those from the lateral-lobe cells innervate the cell-processes of the dorsal body. Neurosecretory granules from these neurites are released at their sites of innervation. The neurites of the optic nerve form synapses with lateral-lobe cell(1), and synapse-like contacts with lateral-lobe cell(2) while a neurite of each canopy cell is found within its collateral optic nerve. Based on the anatomy of the lateral-lobe nerve cells and the optic nerve, it is argued that the stimulatory effect of long days on the dorsal body and on egg production is mediated through the lateral-lobe cells and the canopy cell.     

Intramural neurons in the urinary bladder of the guinea-pig

Summary The urinary bladder of adult female guinea-pigs was stained histochemically to detect the presence of intramural ganglion neurons. Counts on wholemount preparations of entire bladders revealed the presence of 2000–2500 neurons per bladder, either as individual nerve cells or, more often, as ganglia containing up to 40 neurons. Both ganglia and single neurons lie along nerve trunks and are interconnected to form a plexus. Ganglia occur in every part of the bladder; they are more numerous on the dorsal than on the ventral wall, and they are especially abundant in an area within a radius of 800 m from the point of entry into the bladder wall of ureters and urinary arteries. The ganglia are located inside the muscle coat and close to muscle bundles; they usually lie nearer the mucosa than the serosa. Ultrastructurally, each ganglion is surrounded by a capsule; in addition to neurons and glial cells, the ganglia contain capillaries, collagen fibrils and fibroblasts; ganglion neurons are individually wrapped by glial cells and are separated from one another by connective tissue.