Gross morphology of the central nervous system of a phytoseiid mite

The general morphology of the central nervous system is analysed in intact females of the predatory mite, Phytoseiulus persimilis (Acari: Phytoseiidae), using a nucleic acid label (YOYO-1) and confocal laser scanning microscopy. The somata of all cells that comprise the synganglion reside in the cortex. The cortex harbours an estimated total of 10,000 cells. The somata are densely packed in the cortex and cells residing in the inner cortex may only occupy about 1.8 μm. As in all Arachnida, the synganglion is divided in a sub- and a supra-oesophageal nervous mass. Both the cortex and the neuropil appear continuous between these two nervous masses. The sub-oesophageal nervous mass mainly consists of the four paired pedal ganglia that are each associated with a leg. The prominent olfactory lobes are ventrally associated with the first pedal ganglia. A small opisthosomal ganglion occupies the most caudal part of the sub-oesophageal ganglion. The rostral part of the supra-oesophageal nervous mass consists of the paired cheliceral and palpal ganglia. The supra-oesophageal ganglion is the largest ganglion in the supra-oesophageal nervous mass and unlike all other ganglia it is not associated with any of the major nerves. It is therefore more likely involved in secondary information processing.     

The sensory neuropile of the nerve chain of Eurygaster integriceps P

Structure of the sensory neuropil of the abdominal nervous chain has been studied in the Eurygaster integriceps P. by means of methylene blue and paraldehyde fuchsin with phloxin staining. The sensory neuropil consists of three parts: 1) main sensory neuropil, including terminal, T-shaped, antero- and posterconnective fibers; 2) lateral sensory neuropils of the extremities, that in the insect studied, as in the dragon-fly larva, have the form of the overturned eight; 3) system of thick T-shaped fibers getting into the first thoracic ganglion and running along the second nerves, as well as along the thoracic neuromeres of the synganglion, giving collateralies into the nuclei of the extremities and into the main neuropil and coming into both the abdominal and cranial parts. In the neuropil of the extremities certain fibers are revealed; they form collateralies in the nucleus itself and terminate in the main neuropil. Of all the insects investigated it is the Eurygaster integriceps P. that possesses the most developed sensitive nuclei in the extremities and the least developed nuclei in the wings.     

Organization of the sensory system of the earthworm Lumbricus terrestris (Annelida,Clitellata) visualized by DiI

The anatomical organization of the peripheral and central sensory structures of the earthworm Lumbricus terrestris was investigated applying a fluorescent carbocyanine dye (DiI) as a neuronal tracer. Using whole‐mount preparations and confocal laser scanning microscopy, the pattern of primary sensory cells and pathways of their processes were traced and reconstructed in three‐dimensions. Our study shows that a ventral nerve cord ganglion receives sensory fibers from at least two adjacent segments suggesting that the peripheral nervous system is not segmental in its arrangement and the receptive‐fields of the body wall overlap in earthworms. Furthermore, our result suggests an integrative function of the basiepidermal plexus consists of sensory and motor fibers. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

The allometry of the central nervous system during the postembryonic development of the spider Eratigena atrica

During ontogenesis, the size of a spider body, tissues and organs increases dramatically. The aim of the study was to estimate changes in the central nervous system of postembryonic stages of Eratigena atrica and compare them with the literature data on species differing in behavioural traits. Allometric analysis involved evaluation of histological slides embedded in paraffin and stained with hematoxylin and eosin. The reduced major axis regression (RMA) was applied to find allometric relationships between the volumes of the particular parts of the body. All the measured parts of the central nervous system (CNS) were negatively allometrically related to the volume of the prosoma, showing that the increment of the CNS was lower than that of the entire body. The growth of the brain was negatively allometrically related to the growth of the CNS but the increment of the subesophageal ganglion was greater than that of the CNS, exhibiting a positive allometry. Within both these structures, the increase in neuropil volume was greater than the growth of the cortex (cell body rind). Thus, in postembryonic development, the share of the subesophageal ganglion and neuropil in the total volume of the CNS increased, whereas that of the brain and cortex decreased. The mode of the CNS development in E. atrica is similar to that observed in other arthropods, including Argiope aurantia, a spider of different ecology and behaviour.     

Ultrastructure of the synganglion in the larval tickAmblyomma americanum (Ixodoidea: Ixodidae)

The synganglion in the larvalAmblyomma americanum consists of a ganglionic mass pierced by the oesophagus. The nervous tissue consisting of an outer cortex and an inner neuropile is surrounded by an external neurilemma. The cortex comprises perineurium glial cells and neurosecretory and non-neurosecretory neuronal cell bodies. The neuropile consists of nerve fibres ensheathed by glial cells. The entire ganglionic mass is enclosed within a sinus of the circulatory system. No investigations using electron microscopy appear to have been made on the synganglion in the tick larval stage.     

Peculiarities of ultrastructural organization of the metathoracic ganglion in the locustLocusta migratoria larva

In electron microscopic study of structural organization of the thoracic ganglion of the locust larva of the 1st age (1–2 days after hatching), the data on the structure of motoneurons of the 1st nerve, basal and motor neuropil of the larva were obtained. The effector elements of the larval locust CNS are formed rather early and have the structural plan similar to that in adult insects. However, in the larval motoneurons innervating the flight muscles (longitudinal dorsal muscles, wing depressors) the clearly seen features of immaturity of these nervous elements are revealed. Study of the larval ganglion neuropil has shown that the basal neuropil is morphologically formed sufficiently completely as early as in larvae of the first days after hatching. There are shown longitudinal contacts between axons of the ventral neuropil zone, the presence of axons forming theen-passant contacts as well as the synapses with a heterogeneous set of vesicles in the presynaptic area. The presence of the great number of granular vesicles in the basal neuropil of the locust larva may indicate an important role of catecholamines in the early development of the nervous system in the locust larva.     

中华蜜蜂咽下神经节的结构和胚后发育

咽下神经节是昆虫腹神经索的第一个复合神经节, 主要调节口器附肢的活动。本研究通过形态解剖、 BrdU免疫组织化学等技术, 对中华蜜蜂Apis cerana cerana咽下神经节的组织结构和胚后发育过程进行了比较研究。结果表明： 中华蜜蜂的咽下神经节由上颚、 下颚和下唇3个神经节组成。在胚后发育过程中, 细胞增殖的活跃期主要集中在预蛹和蛹发育的第1天, 增殖活动一直持续到蛹发育的第4天结束。根据神经胶质细胞的位置和形态, 咽下神经节中的神经胶质可分为3种类型--表面神经胶质、 皮层神经胶质和神经纤维网神经胶质。本研究为蜜蜂神经系统的发育和功能研究提供了理论基础。     

Architecture of the nervous system in mystacocarida (Arthropoda,crustacea)—An immunohistochemical study and 3D reconstruction

Mystacocarida is a species‐poor group of minute crustaceans with unclear phylogenetic affinities. Previous studies have highlighted the putative “primitiveness” of several mystacocarid features, including the architecture of the nervous system. Recent studies on arthropod neuroarchitecture have provided a wealth of characters valuable for phylogenetic reconstructions. To permit and facilitate comparison with these data, we used immunohistochemical labeling (against acetylated α‐tubulin, serotonin and FMRFamide) on the mystacocarid Derocheilocaris remanei, analyzing it with confocal laser‐scanning microscopy and 3D reconstruction. The mystacocarid brain is fairly elongated, exhibiting a complicated stereotypic arrangement of neurite bundles. However, none of the applied markers provided evidence of structured neuropils such as a central body or olfactory glomeruli. A completely fused subesophageal ganglion is not present, all segmental soma clusters of the respective neuromeres still being delimitable. The distinct mandibular commissure comprises neurite bundles from more anterior regions, leading us to propose that it may have fused with an ancestral posterior tritocerebral commissure. The postcephalic ventral nervous system displays a typical ladder‐like structure with separated ganglia which bears some resemblance to larval stages in other crustaceans. Ganglia and commissures are also present in the first three limbless “abdominal” segments, which casts doubt on the notion of a clear‐cut distinction between thorax and abdomen. An unpaired longitudinal median neurite bundle is present and discussed as a potential tetraconate autapomorphy. Additionally, a paired latero‐longitudinal neurite bundle extends along the trunk. It is connected to the intersegmental nerves and most likely fulfils neurohemal functions. We report the complete absence of serotonin‐ir neurons in the ventral nervous system, which is a unique condition in arthropods and herein interpreted as a derived character. J. Morphol., 2010. © 2009 Wiley‐Liss, Inc.     

Metamorphosis of wing motor system in the silk moth,Bombyx mori L. (Lepidoptera: Bombycidae): Anatomy of the sensory and motor neurons that innervate larval mesothoracic dorsal musculature,stretch receptors,and epidermis

Anatomy of dorsal mesothoracic structures, such as muscles, sensory organs, and innervation, was studied in the silkworm, Bombyx mori L. (Lepidoptera : Bombycidae), and compared with the adult wing motor system. Musculature and nerve innervation were investigated by dissection and electron micrograph; and central projection of sensory fibers and morphology of somata and dendrites of motor neurons by cobalt back-filling, followed by silver intensification. There are 23 muscle bundles (DLM) and 2 stretch receptors (SR). The DLMs, SRs, and epidermis are innervated by a branch of the dorsal nerve trunk emerging from the mesothoracic ganglion (MSG). The branch bifurcates into a dorsal sensory branch of about 300 sensory fibers and a dorsal motor branch of 14 fibers. The sensory fibers project mainly to a longitudinal portion near the mid line in the ventral neuropil of MSG and the metathoracic ganglion. Several fibers extend into the prothoracic ganglion (PG) and a few into the subesophageal and 1st abdominal ganglia. At least 13 (probably 14) motor neurons send axons to DLMs: 9 (probably 10) in PG, and 4 in MSG. Their dendrites are located mostly on the dorsoipsilateral side of the neuropil, but several branches cross the mid line and give rise to many fine branches on the contralateral side. Comparison between the larval (present study) and adult motor system shows a significant similarity in the musculature, peripheral nerve pattern, and motor neurons with some peculiarities.     

The delineation of the fourth walking leg segment is temporally linked to posterior segmentation in the mite Archegozetes longisetosus (Acari: Oribatida,Trhypochthoniidae)

Acari (mites and ticks) lack external segmentation, with the only indication of segmentation being the appendages of the prosoma (chelicerae, pedipalps, and four pairs of walking legs). Acari also have a mode of development in which the formation of the fourth walking leg is suppressed until the nymphal stages, following a hexapodal larva. To determine the number of segments in the posterior body region (opisthosoma) of mites, and to also determine when the fourth walking leg segment is delineated during embryogenesis, we followed the development of segmentation in the oribatid mite Archegozetes longisetosus using time‐lapse and scanning electron microscopy, as well as in situ hybridizations of the A. longisetosus orthologues of the segmentation genes engrailed and hedgehog. Our data show that A. longisetosus patterns only two opisthosomal segments, indicating a large degree of segmental fusion or loss. Also, we show that the formation of the fourth walking leg segment is temporally tied to opisthosomal segmentation, the first such observation in any arachnid.     

Proctolin in the brain and ganglia of Triatoma infestans (Hemiptera: Reduviidae)

The distribution of proctolin in the central nervous system of the hemipteran bug, Triatoma infestans, was studied by immunohistochemistry using the sensitive avidin‐biotin technique combined with nickel salt intensification of the reaction product. Proctolin was present in cells and fibers of the brain and ganglia. In the brain, protocerebral proctolin‐immunoreactive cell bodies were found in the pars intercerebralis, the optic lobes, and the lateral soma rind. The deutocerebrum showed positive somata in relation to the antennal motor center and the tritocerebrum had intense immunoreactive fibers but few positive cells. Proctolin‐immunoreactive cell bodies of different sizes were observed in the subesophageal ganglion. Large cell bodies were found mainly rostrally and beaded positive processes were present around the ventral border of the esophageal foramen and in the rostrolateral neuropil of this ganglion. Small‐ to medium‐sized positive somata were found in the posterior part of the prothoracic ganglion; some of these cells were sending immunoreactive processes to the central neuropil. The meso‐metathoracic‐abdominal ganglionic mass showed positive cells in all the neuromeres, where some of them were large and had thick immunoreactive granules. The results show that the labeling pattern of proctolin‐like immunoreactivity in Triatoma i. appears to be widespread and unique for its central nervous system. It is suggested that proctolin may serve neuroendocrine, integrative, and motor functions in the brain of T. infestans. J. Morphol. 240:39–47, 1999. © 1999 Wiley‐Liss, Inc.     

A Study of Glutathione <Emphasis Type="Italic">S</Emphasis>-transferase pi Expression in Central Nervous System of Subjects with Amyotrophic Lateral Sclerosis Using RNA Extraction from Formalin-Fixed,Paraffin-Embedded Material

The expression of glutathione S-transferase pi (GST pi), an enzyme responsible for inactivation of a large variety of toxic compounds was studied in spinal cord, motor and sensory brain cortex obtained from patients who died in the course of amyotrophic lateral sclerosis (ALS). The studies were performed on formalin-fixed, paraffin-embedded (FFPE) and freshly frozen tissues. The method of RNA isolation from FFPE was modified. A significant decrease of GST pi-mRNA expression was found in cervical spinal cord and motor brain cortex of ALS subjects comparing to analogue control tissues (P < 0.01), as well as in motor cortex of ALS subjects comparing to their sensory cortex (P < 0.05). In spinal cords the decrease in GST pi-mRNA expression was accompanied by a decrease of GST pi protein level. Results indicated lowered GST pi expression on both mRNA and protein levels in the regions of nervous system affected by ALS. The non-properly inactivated by GST toxic electrophiles and organic peroxides may thus contribute to motor neurons damage.     

Dendritic reorganization of an identified neuron during metamorphosis of the moth Manduca sexta: The influence of interactions with the periphery

During metamorphosis of the moth, Manduca sexta, an identified leg motor neuron, the femoral extensor motor neuron (FeExt MN) undergoes dramatic reorganization. Larval dendrites occupy two distinct regions of neuropil, one in the lateral leg neuropil and a second in dorsomedial neuropil. Adult dendrites occupy a greater volume of lateral leg neuropil but do not extend to the dorsomedial region of the ganglion. The adult dendritic morphology is acquired by extreme dendritic regression followed by extensive dendritic growth. Towards the end of larval life, MN dendrites begin to regress, but the most dramatic loss of dendrites occurs in the 3 days following pupation, such that only a few sparse dendrites are retained in the lateral region of leg neuropil. Extensive dendritic growth occurs over the subsequent days such that the MN acquires an adult-like morphology between 12 and 14 days after pupation. This basic process of dendritic remodeling is not dependent upon the presence of the adult leg, suggesting that neither contact with the new target muscle nor inputs from new leg sensory neurons are necessary for triggering dendritic changes. The final distribution of MN dendrites in the adult, however, is altered when the adult leg is absent, suggesting that cues from the adult leg are involved in directing or shaping the growth of MN dendrites to specific regions of neuropil. © 1993 John Wiley & Sons, Inc.     

Nervous system development in the fairy shrimp Branchinella sp. (Crustacea: Branchiopoda: Anostraca): Insights into the development and evolution of the branchiopod brain and its sensory organs

Using immunohistochemical labeling against acetylated a‐tubulin and serotonin in combination with confocal laser scanning microscopy and 3D‐reconstruction, we investigated the temporary freshwater pond inhabitant Branchinella sp. (Crustacea: Branchiopoda: Anostraca) for the first time to provide detailed data on the development of the anostracan nervous system. Protocerebral sense organs such as the nauplius eye and frontal filament organs are present as early as the hatching stage L0. In the postnaupliar region, two terminal pioneer neurons grow from posterior to anterior to connect the mandibular neuromeres. The first protocerebral neuropil to emerge is not part of the central complex but represents the median neuropil, and begins to develop from L0+ onwards. In stage L3, the first evidence of developing compound eyes is visible. This is followed by the formation of the visual neuropils and the neuropils of the central complex in the protocerebrum. From the deutocerebral lobes, the projecting neuron tract proceeds to both sides of the lateral protocerebrum, forming a chiasma just behind the central body. In the postnaupliar region, the peripheral nervous system, commissures and connectives develop along an anterior–posterior gradient after the fasciculation of the terminal pioneer neurons with the mandibular neuromere. The peripheral nervous system in the thoracic segments consists of two longitudinal neurite bundles on each side which connect the intersegmental nerves, together with the ventral nervous system forming an orthogon‐like network. Here, we discuss, among other things, the evidence of a fourth nauplius eye nerve and decussating projecting neuron tract found in Branchinella sp., and provide arguments to support our view that the crustacean frontal filament (organ) and onychophoran primary antenna are homologous. J. Morphol. 277:1423–1446, 2016. © 2016 Wiley Periodicals, Inc.     

Morphology and ultrastructure of the anterior end of Diplocirrus longisetosus Marenzeller, 1890 (Flabelligeridae, Polychaeta, Annelida)

The morphology and ultrastructure of the sedentary polychaete Diplocirrus longisetosus Marenzeller, 1890, collected from the White Sea, were studied using dissection, histological methods, light microscopy, and both scanning and transmission electron microscopy. The prostomium and peristomium carry a pair of palps, eight branchiae, a pair of nuchal organs and two nephridiopores, ciliated folds and the mouth. The prostomium, peristomium and the first chaetigerous segment with all appendages comprise the so-called siphon complex. The mouth leads to a pharyngeal organ that is closed ventrally and composed of a ventral muscle bulb adjoined dorsally by two folds projecting into the pharyngeal lumen. These parts are connected and enveloped by the longitudinal investing muscle. No tongue-like organ is present. The nervous system of the siphonal part comprises the brain, the circum-oesophageal connectives and the ganglia of the peristomium and first chaetigerous segment.     

Histamine immunoreactivity in the central nervous system of the spider Cupiennius salei

In this study, immunohistochemistry on Vibracut sections is used to demonstrate anti-histamine immunoreactivity in the brain of the spider, Cupiennius salei (Keys.) (Ctenidae). We describe a system of histamine-immunoreactive neurons within the central nervous system that consists of six omnisegmental neurons. These histamine-immunoreactive neurons form two subgroups: a dorsal system with two cells per hemisphere and a ventral system with only one cell per hemisphere. The cells have extended arborizations in the motor and sensory areas of all neuromeres in the suboesophageal ganglionic mass. We have also found histamine immunoreactivity in the photoreceptors of C. salei and suggest that histamine is a neurotransmitter of photoreceptors in all arthropods, since it is also known to occur in the photoreceptors of the other main arthropod taxa (Merostomata, Crustacea, and Insecta).     

Depletions in the cervical and thoracolumbar sympathetic system following removal of neural crest from the embryo of Chelydra serpentina

Neural crest and dorsal neural tube of cervical and thoracolumbar levels were removed from embryos of Chelydra serpentina at stages ranging from 8 to 18 somites. Extirpation extended from the levels of the last four somites posteriorly around the neurenteric canal. Deficiencies in sensory and sympathetic ganglia occurred. Motor roots of the associated spinal nerves differentiated. In the absence of postganglionic neurons, the preganglionic fibers form a neuron-free plexus in the thoracolumbar region. Some observations in the cervical region indicate that the postganglionic neurons depend on preganglionic fibers for their differentiation. The cortex of the adrenal gland formed without related medulla in appropriate experiments. The normal morphology of the sympathetic trunks is illustrated. Superficial and deep cervical sympathetic trunks are described. The latter ascends the neck in a paravertebral position. Along its course are segmental ganglia and rami communicantes; it terminates by joining the medial branch of the superficial sympathetic trunk rostral to the ninth cranial nerve.     

Functional organization of the arctiid moth tymbal (insecta,lepidoptera)

The exoskeletal morphology, muscular organization, and innervation patterns of the tymbals of seven sound-producing species of tiger moths (Arctiidae) were compared with the undifferentiated episterna of two silent species. At least three muscles are involved in sound production: the tymbal muscle, pv2, and the accessory muscles, pvl and/or pv6. All of the tymbal muscles are innervated by the IIIN2a branch of the metathoracic leg nerve, which contains two axons larger than the others. Backfills of the tymbal branch of the IIIN2a reveal a medial sensory neuropil and a population of five ipsilateral motor neurons whose somata are clustered into three groups along the anterior edge of the metathoracic ganglion. The dendritic arborizations of the motor neurons extend to the ganglionic midline but are separate from one part of the auditory neuropil observed in other noctuoids. The study concludes that the arctiid tymbal reveals only minor modifications (e.g., cuticle thinning) of the episterna of silent moths and represents a primitive form of the tymbal compared to those of the Cicadidae.