Three-dimensional atlas of thoracic ganglia in the praying mantis, Tenodera aridifolia.

The praying mantis is a good model for the study of motor control, especially for investigating the transformation from sensory signals into motor commands. In insects, thoracic ganglia (TG) play an important role in motor control. To understand the functional organization of TG, an atlas is useful. However, except for the fruitfly, no three-dimensional atlas of TG has not been reported for insects. In this study, we generated a three-dimensional atlas of prothoracic, mesothoracic, and metathoracic ganglia in the praying mantis (Tenodera aridifolia). First, we observed serial sections of the prothoracic ganglion stained with hematoxylin and eosin to identify longitudinal tracts and transverse commissures. We then visualized neuropil areas by immunostaining whole-mount TG with an anti-synapsin antibody. Before labeling each neuropil area, standardization using the iterative shape averaging method was applied to images to make neuropil contours distinct. Neuropil areas in TG were defined based on their shape and relative position to tracts and commissures. Finally, a three-dimensional atlas was reconstructed from standardized images of the TG. The standard TG are available at the Comparative Neuroscience Platform website (cns.neuroinf.jp/modules/xoonips/detail.php?item_id=11946) and can be used as a common reference map to combine the anatomical data obtained from different individuals.

Comparative Study of Pygidial Organization in Polychaetes of the Families Nephtyidae and Syllidae.

The first comparative study of the polychaete pygidial region has been performed using confocal scanning microscopy and immunohistochemical methods. Fundamentally new data has been obtained on the pygidial organization in representatives the Nephtyidae and Syllidae families. Despite differences in the overall morphology of pygidium, it is characterized by a certain structural plan as a whole that can be the basis for that of all polychaetes. Some insignificant differences in the pygidial structure can be either species-specific or consequences of mutations and seem to have no fundamental importance for the general organization.

The stomatogastric nervous system of the medicinal leech: its anatomy, physiology and associated aminergic neurons.

Blood feeding is an essential and signature activity of the medicinal leech species Hirudo verbana. Despite keen interest in understanding the neuronal substrates of this behavior, a major component of the nervous system associated with feeding has remained overlooked. In this study, for the first time, we report on the presence and characteristics of five stomatogastric ganglia (STGs) comprising the visceral stomatogastric nervous system (STN) of the leech. Although a brief report was published by Ruth Hanke in 1948 indicating that a ring of three ganglia (not five) was associated with the cephalic ganglia, this information was never integrated into subsequent neurobiological studies of feeding. Here, the anatomical features of the STGs are described, as are the morphological and electrophysiological characteristics of neurons originating in them. We also determined that two of the five STGs (STG-1 and STG-3) each contained two relatively large (ca. 40 µm diameter) serotonergic neurons. The STN was also enriched with dopaminergic and serotonergic arborizations; however, no intrinsic dopaminergic somata were observed. The trajectory of the serotonergic large lateral (LL) neuron, a command-like cell for feeding, was documented to project directly to the STN and not to the jaw and pharyngeal musculature as previously reported, thus reopening the important question of how the LL cell activates and coordinates biting activity with pharyngeal swallowing. Additional studies revealed that the LL cell is excited by blood serum applied to the lip and is strongly inhibited by dopamine. These findings provide a new foundation for understanding the regulation and modulation of neural networks involved in feeding.

Neuroanatomy of Hyalinella punctata: Common patterns and new characters in phylactolaemate bryozoans.

Studies on the bryozoan adult nervous system employing immunocytochemical techniques and confocal laser scanning microscopy are scarce. To gain a better view into the structure and evolution of the nervous system of the Phylactolaemata, the earliest extant branch and sister taxon to the remaining Bryozoa, this work aims to characterize the nervous system of Hyalinella punctata with immunocytochemical techniques and confocal laser scanning microscopy. The cerebral ganglion is located between the anus and the pharynx and contains a lumen. Two ganglionic horns and a circum-oral nerve ring emanate from the cerebral ganglion. The pharynx is innervated by a diffuse neural plexus with two prominent neurite bundles. The caecum is innervated by longitudinal neurite bundles and a peripheral plexus. The intestine is characterized by longitudinal and circular neurite bundles, mostly near the anus. Novel putative sensory cells were found in the foregut and intestine. The tentacle sheath is innervated by a diffuse neural plexus, which emanates from several neurite bundles from the cerebral ganglion, but also parts of the pharyngeal plexus. There are six tentacle neurite bundles of intertentacular origin. The retractor muscles are innervated by two thin neurite bundles. Several characters are described herein for the first time in Phylactolaemata: Longitudinal neurite bundles and a peripheral plexus of the caecum, putative sensory structures of the gut, retractor muscle innervation, specific duplicature band neurite bundles. The tentacle innervation differs from previous descriptions of phylactolaemates regarding the origin of the three abfrontal neurite bundles. In general, most organ systems are innervated by a diffuse plexus in phylactolaemates as opposed to gymnolaemates. In contrast to the Gymnolaemata, representatives of Phylactolaemata show a higher number of tentacle nerves. Although the plesiomorphic condition for zooidal features among bryozoans remains unclear, having a diffuse nerve plexus may represent an ancestral feature for freshwater bryozoans.

When complex neuronal structures may not matter.

Much work has explored animal-to-animal variability and compensation in ion channel expression. Yet, little is known regarding the physiological consequences of morphological variability. We quantify animal-to-animal variability in cable lengths (CV = 0.4) and branching patterns in the Gastric Mill (GM) neuron, an identified neuron type with highly-conserved physiological properties in the crustacean stomatogastric ganglion (STG) of Cancer borealis. We examined passive GM electrotonic structure by measuring the amplitudes and apparent reversal potentials (Erevs) of inhibitory responses evoked with focal glutamate photo-uncaging in the presence of TTX. Apparent Erevs were relatively invariant across sites (mean CV ± SD = 0.04 ± 0.01; 7-20 sites in each of 10 neurons), which ranged between 100-800 µm from the somatic recording site. Thus, GM neurons are remarkably electrotonically compact (estimated λ > 1.5 mm). Electrotonically compact structures, in consort with graded transmission, provide an elegant solution to observed morphological variability in the STG.

Spatial distribution of intermingling pools of projection neurons with distinct targets: A 3D analysis of the commissural ganglia in Cancer borealis.

Projection neurons play a key role in carrying long-distance information between spatially distant areas of the nervous system and in controlling motor circuits. Little is known about how projection neurons with distinct anatomical targets are organized, and few studies have addressed their spatial organization at the level of individual cells. In the paired commissural ganglia (CoGs) of the stomatogastric nervous system of the crab Cancer borealis, projection neurons convey sensory, motor, and modulatory information to several distinct anatomical regions. While the functions of descending projection neurons (dPNs) which control downstream motor circuits in the stomatogastric ganglion are well characterized, their anatomical distribution as well as that of neurons projecting to the labrum, brain, and thoracic ganglion have received less attention. Using cell membrane staining, we investigated the spatial distribution of CoG projection neurons in relation to all CoG neurons. Retrograde tracing revealed that somata associated with different axonal projection pathways were not completely spatially segregated, but had distinct preferences within the ganglion. Identified dPNs had diameters larger than 70% of CoG somata and were restricted to the most medial and anterior 25% of the ganglion. They were contained within a cluster of motor neurons projecting through the same nerve to innervate the labrum, indicating that soma position was independent of function and target area. Rather, our findings suggest that CoG neurons projecting to a variety of locations follow a generalized rule: for all nerve pathway origins, the soma cluster centroids in closest proximity are those whose axons project down that pathway.

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda.

Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.

Deep-tissue confocal imaging of the central projections of ovipositor sensory afferents in the Egyptian cotton leafworm, Spodoptera littoralis.

The pre-ovipositon behavior of moths is largely dependent upon the cues that a gravid female perceives while assessing potential oviposition sites. Assessment of such sites is accomplished, at least in part, by mechanosensory and gustatory sensilla located on the ovipositor whose sensory neurons project into the terminal abdominal ganglion (TAG). Using anterograde backfill staining, confocal laser scanning microscopy, and three dimensional reconstruction, we traced and analyzed the central projections of the sensory neurons housed in the sensilla located on the ovipositor papillae and explored the neuropilar composition of the TAG in the Egyptian cotton leafworm, Spodoptera littoralis. The TAG consists of three fused neuromeres (6-8th Ner) associated with the 6-8th abdominal segments. Within the TAG, and specifically in the 8th neuromere, four unstructured neuropilar compartments are present; the dorso-ipsilateral motor neuropil (MN), the medio-ipsilateral mechanosensory neuropil (MchN), the medio-ipsilateral small gustatory neuropil (GN), and the medio-contralateral posterior ovipositor glomerulus (Og). The Og appears quite compact, with a hollow core free of terminal arborizations. The MchN is further subdivided into 4 unstructured glomeruli in the 8th neuromere, whose afferents are subsequently extended into 3 glomeruli in the 7th and 6th neuromeres. Few neurites of the Og are populated with large dense varicosities reminiscent of neurosecretory vesicles. Given that all ovipositor nerves converge into a common ganglionic center, the TAG, we assume that this ganglion may be a center for coordination of oviposition behaviors, including movements of the ovipositor during assessment of oviposition substrates and egg laying in S. littoralis.

Neuroanatomy of the optic ganglia and central brain of the water flea Daphnia magna (Crustacea, Cladocera).

We reveal the neuroanatomy of the optic ganglia and central brain in the water flea Daphnia magna by use of classical neuroanatomical techniques such as semi-thin sectioning and neuronal backfilling, as well as immunohistochemical markers for synapsins, various neuropeptides and the neurotransmitter histamine. We provide structural details of distinct neuropiles, tracts and commissures, many of which were previously undescribed. We analyse morphological details of most neuron types, which allow for unravelling the connectivities between various substructural parts of the optic ganglia and the central brain and of ascending and descending connections with the ventral nerve cord. We identify 5 allatostatin-A-like, 13 FMRFamide-like and 5 tachykinin-like neuropeptidergic neuron types and 6 histamine-immunoreactive neuron types. In addition, novel aspects of several known pigment-dispersing hormone-immunoreactive neurons are re-examined. We analyse primary and putative secondary olfactory pathways and neuronal elements of the water flea central complex, which displays both insect- and decapod crustacean-like features, such as the protocerebral bridge, central body and lateral accessory lobes. Phylogenetic aspects based upon structural comparisons are discussed as well as functional implications envisaging more specific future analyses of ecotoxicological and endocrine disrupting environmental chemicals.

Anatomical study of preganglionic spinal nerve and disc relation at different lumbar levels: Special aspect for microscopic spine surgery.

BACKGROUND: Lumbar microdiscectomy is a widespread popular method of treatment. One major challenge is the spine level dependent different anatomy and the limited sight on the nerve root during the surgical procedure. OBJECTIVE: The aim was to analyze the specific anatomic relation of nerve root, intervertebral disc and intervertebral ganglion under determination of the specific nerve distances. Furthermore the relation between the disc and the corresponding nerve root was evaluated. METHODS: Regular human lumbar spine specimens of body donors were included in the study. Microscopic assisted dissection was performed. The topographical distances between a defined disc measurement point (DP) and the corresponding nerve root shoulder (NS) were measured. The preganglionic distance from the caudal axilla point (AP) of the spinal nerve root and the center point (CG) of the spinal ganglion in the intervertebral foramen were determined. RESULTS: The AP-CG distance increased gradually in the caudal direction from L1 (7.25 ± 2.72 mm right side, 7.30 ± 2.85 mm left side) to a maximum for L5 (16.00 ± 3.39 mm right side, 16.50 ± 3.58 mm left side, p< 0.05). We found a significant reduction for S1 (14.88 ± 3.42 mm right side, 13.83 ± 2.47 mm, p< 0.05). In contrast the DP-AP distances showed a maximum for L1 (12.75 ± 2.78 mm right side, 13.70 ± 3.87 mm left side) with an increasing shortening in the caudal direction and even negative values for S1 (-2.63 ± 3.31 mm right side, -0.83 ± 2.84 mm left side, p< 0.01). CONCLUSION: The topographical anatomy changes each lumbar segment and demands therefore an exact preoperative planning using this specific knowledge to perform a successful microscopic spine surgery. The results of the study support a better understanding of the relevant anatomy and help to reduce incomplete herniated disc removal and to avoid surgical complications.

Octopamine-like immunoreactive neurons in the brain and subesophageal ganglion of the parasitic wasps Nasonia vitripennis and N. giraulti.

Octopamine is an important neuromodulator in the insect nervous system, influencing memory formation, sensory perception and motor control. In this study, we compare the distribution of octopamine-like immunoreactive neurons in two parasitic wasp species of the Nasonia genus, N. vitripennis and N. giraulti. These two species were previously described as differing in their learning and memory formation, which raised the question as to whether morphological differences in octopaminergic neurons underpinned these variations. Immunohistochemistry in combination with confocal laser scanning microscopy was used to reveal and compare the somata and major projections of the octopaminergic neurons in these wasps. The brains of both species showed similar staining patterns, with six different neuron clusters being identified in the brain and five different clusters in the subesophageal ganglion. Of those clusters found in the subesophageal ganglion, three contained unpaired neurons, whereas the other three consisted in paired neurons. The overall pattern of octopaminergic neurons in both species was similar, with no differences in the numbers or projections of the ventral unpaired median (VUM) neurons, which are known to be involved in memory formation in insects. In one other cluster in the brain, located in-between the optic lobe and the antennal lobe, we detected more neurons in N. vitripennis compared with N. giraulti. Combining our results with findings made previously in other Hymenopteran species, we discuss possible functions and some of the ultimate factors influencing the evolution of the octopaminergic system in the insect brain.

A map of taste neuron projections in the Drosophila CNS.

We provide a map of the projections of taste neurons in the CNS of Drosophila. Using a collection of 67 GAL4 drivers representing the entire repertoire of Gr taste receptors, we systematically map the projections of neurons expressing these drivers in the thoracico-abdominal ganglion and the suboesophageal ganglion (SOG). We define 9 categories of projections in the thoracico-abdominal ganglia and 10 categories in the SOG. The projection patterns are modular, and can be interpreted as combinations of discrete pattern elements. The elements can be interpreted in terms of the taste organ from which the projections originate, the structures from which they originate, and the quality of taste information that they represent. The extensive diversity in projection patterns provides an anatomical basis for functional diversity in responses elicited by different taste stimuli.

Organization of columnar inputs in the third optic ganglion of a highly visual crab.

Motion information provides essential cues for a wide variety of animal behaviors such as mate, prey, or predator detection. In decapod crustaceans and pterygote insects, visual codification of object motion is associated with visual processing in the third optic neuropile, the lobula. In this neuropile, tangential neurons collect motion information from small field columnar neurons and relay it to the midbrain where behavioral responses would be finally shaped. In highly ordered structures, detailed knowledge of the neuroanatomy can give insight into their function. In spite of the relevance of the lobula in processing motion information, studies on the neuroarchitecture of this neuropile are scant. Here, by applying dextran-conjugated dyes in the second optic neuropile (the medulla) of the crab Neohelice, we mass stained the columnar neurons that convey visual information into the lobula. We found that the arborizations of these afferent columnar neurons lie at four main lobula depths. A detailed examination of serial optical sections of the lobula revealed that these input strata are composed of different number of substrata and that the strata are thicker in the centre of the neuropile. Finally, by staining the different lobula layers composed of tangential processes we combined the present characterization of lobula input strata with the previous characterization of the neuroarchitecture of the crab's lobula based on reduced-silver preparations. We found that the third lobula input stratum overlaps with the dendrites of lobula giant tangential neurons. This suggests that columnar neurons projecting from the medulla can directly provide visual input to the crab's lobula giant neurons.

Neuronal projections and putative interaction of multimodal inputs in the subesophageal ganglion in the blowfly, Phormia regina.

In flies, the maxillary palp possesses olfactory sensilla housing olfactory receptor neurons (ORNs), which project to the primary olfactory center, the antennal lobes (ALs). The labellum possesses gustatory sensilla housing gustatory receptor neurons (GRNs), which project to the primary gustatory center, the subesophageal ganglion (SOG). Using an anterograde staining method, we investigated the axonal projections of sensory receptor neurons from the maxillary palp and labellum to the SOG or other parts of brain in the blowfly, Phormia regina. We show that maxillary mechanoreceptor neurons and some maxillary ORNs project to the SOG where they establish synapses, whereas other maxillary ORNs terminate in the ipsi- and contralateral ALs. The labellar GRNs project to the SOG, and some of these neural projections partially overlap with ORN terminals from the maxillary palp. Based on these anterograde staining data and 3D models of the observed axonal projections, we suggest that interactions occur between GRNs from the labellum and ORNs from the maxillary palp. These observations strongly suggest that olfactory information from the maxillary palp directly interacts with the processing of gustatory information within the SOG of flies.

Notable plesiomorphies and notable specializations: head structure of the primitive "tongue moth" Acanthopteroctetes unifascia (Lepidoptera: Acanthopteroctetidae).

The Acanthopteroctetidae are one of the first-originated family-group lineages within "tongue moths" (Lepidoptera-Glossata). The purpose of this study is to provide a comprehensive account (based on whole mount preparations, serial sections, and Scanning electron microscopy) of the cephalic structure of an adult exemplar of the family, to supplement the sparse available information. Notable plesiomorphies include the retention of frontal retractors of the narrow labrum, a high supraocular index linked to strong development of cranio-mandibular ad- and abductors, and perhaps the unusually short but still coilable (just ca. 1.5 turns) galeal "tongue." Notable specializations (probably mostly family autapomorphies) include a complement of large sensilla placodea on the male antennae, an apical attachment of the long dorsal tentorial arm to the cranium, an extreme reduction of the single-segmented labial palps, a particularly strong subgenal bridge and a surface structure of near-parallel ridges on the ommatidial corneae. The presence of sizable saccular mandibular (type 1) glands opening into the adductor apodeme is unexpected, no counterparts being known from neighboring taxa. The same is true for ventral salivarium dilator muscles originating on the prelabium; and tentatively suggested to be homologues of the extrinsic palp flexors (the insertion shift being related to loss of original function due to palp reduction), rather than to the ventral salivarium muscles of more basal insects. A complete "deutocerebral loop"' may or may not be developed, as is true for a mutual appression of the optic lobe and circumoesophageal connective/suboesophageal ganglion, enclosing the anterior tentorial arm between them; a suboesophageal innervation of the retrocerebral complex was not observed. No characters bearing on the monophyly of the Coelolepida were identified. The scapo-pedicellar articulation with a scapal process and a smooth intercalary sclerite is reminiscent of conditions in Neopseustidae, but remains debatable as a synapomorphy of the two families.

The ventral nerve cord in Cephalocarida (Crustacea): new insights into the ground pattern of Tetraconata.

Cephalocarida are Crustacea with many anatomical features that have been interpreted as plesiomorphic with respect to crustaceans or Tetraconata. While the ventral nerve cord (VNC) has been investigated in many other arthropods to address phylogenetic and evolutionary questions, the few studies that exist on the cephalocarid VNC date back 20 years, and data pertaining to neuroactive substances in particular are too sparse for comparison. We reinvestigated the VNC of adult Hutchinsoniella macracantha in detail, combining immunolabeling (tubulin, serotonin, RFamide, histamine) and nuclear stains with confocal laser microscopy, complemented by 3D-reconstructions based on serial semithin sections. The subesophageal ganglion in Cephalocarida comprises three segmental neuromeres (Md, Mx1, Mx2), while a separate ganglion occurs in all thoracic segments and abdominal segments 1-8. Abdominal segments 9 and 10 and the telson are free of ganglia. The maxillar neuromere and the thoracic ganglia correspond closely in their limb innervation pattern, their pattern of mostly four segmental commissures and in displaying up to six individually identified serotonin-like immunoreactive neurons per body side, which exceeds the number found in most other tetraconates. Only two commissures and two serotonin-like immunoreactive neurons per side are present in abdominal ganglia. The stomatogastric nervous system in H. macracantha corresponds to that in other crustaceans and includes, among other structures, a pair of lateral neurite bundles. These innervate the gut as well as various trunk muscles and are, uniquely, linked to the unpaired median neurite bundle. We propose that most features of the cephalocarid ventral nerve cord (VNC) are plesiomorphic with respect to the tetraconate ground pattern. Further, we suggest that this ground pattern includes more serotonin-like neurons than hitherto assumed, and argue that a sister-group relationship between Cephalocarida and Remipedia, as favored by recent molecular analyses, finds no neuroanatomical support.

Neuropilar projections of the anterior gastric receptor neuron in the stomatogastric ganglion of the Jonah crab, Cancer borealis.

Sensory neurons provide important feedback to pattern-generating motor systems. In the crustacean stomatogastric nervous system (STNS), feedback from the anterior gastric receptor (AGR), a muscle receptor neuron, shapes the activity of motor circuits in the stomatogastric ganglion (STG) via polysynaptic pathways involving anterior ganglia. The AGR soma is located in the dorsal ventricular nerve posterior to the STG and it has been thought that its axon passes through the STG without making contacts. Using high-resolution confocal microscopy with dye-filled neurons, we show here that AGR from the crab Cancer borealis also has local projections within the STG and that these projections form candidate contact sites with STG motor neurons or with descending input fibers from other ganglia. We develop and exploit a new masking method that allows us to potentially separate presynaptic and postsynaptic staining of synaptic markers. The AGR processes in the STG show diversity in shape, number of branches and branching structure. The number of AGR projections in the STG ranges from one to three simple to multiply branched processes. The projections come in close contact with gastric motor neurons and descending neurons and may also be electrically coupled to other neurons of the STNS. Thus, in addition to well described long-loop pathways, it is possible that AGR is involved in integration and pattern regulation directly in the STG.

Deep homology of arthropod central complex and vertebrate basal ganglia.

The arthropod central complex and vertebrate basal ganglia derive from embryonic basal forebrain lineages that are specified by an evolutionarily conserved genetic program leading to interconnected neuropils and nuclei that populate the midline of the forebrain-midbrain boundary region. In the substructures of both the central complex and basal ganglia, network connectivity and neuronal activity mediate control mechanisms in which inhibitory (GABAergic) and modulatory (dopaminergic) circuits facilitate the regulation and release of adaptive behaviors. Both basal ganglia and central complex dysfunction result in behavioral defects including motor abnormalities, impaired memory formation, attention deficits, affective disorders, and sleep disturbances. The observed multitude of similarities suggests deep homology of arthropod central complex and vertebrate basal ganglia circuitries underlying the selection and maintenance of behavioral actions.

Morphological analysis of the primary center receiving spatial information transferred by the waggle dance of honeybees.

The waggle dancers of honeybees encodes roughly the distance and direction to the food source as the duration of the waggle phase and the body angle during the waggle phase. It is believed that hive-mates detect airborne vibrations produced during the waggle phase to acquire distance information and simultaneously detect the body axis during the waggle phase to acquire direction information. It has been further proposed that the orientation of the body axis on the vertical comb is detected by neck hairs (NHs) on the prosternal organ. The afferents of the NHs project into the prothoracic and mesothoracic ganglia and the dorsal subesophageal ganglion (dSEG). This study demonstrates somatotopic organization within the dSEG of the central projections of the mechanosensory neurons of the NHs. The terminals of the NH afferents in dSEG are in close apposition to those of Johnston's organ (JO) afferents. The sensory axons of both terminate in a region posterior to the crossing of the ventral intermediate tract (VIT) and the maxillary dorsal commissures I and III (MxDCI, III) in the subesophageal ganglion. These features of the terminal areas of the NH and JO afferents are common to the worker, drone, and queen castes of honeybees. Analysis of the spatial relationship between the NH neurons and the morphologically and physiologically characterized vibration-sensitive interneurons DL-Int-1 and DL-Int-2 demonstrated that several branches of DL-Int-1 are in close proximity to the central projection of the mechanosensory neurons of the NHs in the dSEG.

[Peculiarities of the structural-functional organization of motor neuropil of dragonfly thoracic ganglia].

The work considers the structural-functional relations existing in the motor neuropil of thoracic ganglia of dragonflies - the animals able to perform very complex and fast maneuvers in the flight. The motor neuropil in dragonflies is shown to be more differentiated than in the lees mobile insects, while motor nuclei in neuropil are more clearly outlined and closer to each other. There are revealed dendrites of motoneurons of pedal muscles (the middle nucleus), which are running into the anterior and posterior nuclei that contain dendrites of motoneurons of wing muscles. A possible role of such approaching is discussed for close functional interaction of wing and foot muscles, which is necessary to dragonflies during flight at their catching of large insects with aid of legs. Peculiarities are considered in structural organization of motoneurons of wing muscles dragonflies and locusts, which indicate the greater functional possibilities peculiar to motoneurons of the dragonflies motor apparatus.