Central afferent pathways of long hair sensilla in the ventral nerve cord of the Indian black scorpion,Heterometrus fulvipes Koch

Histological and electrophysiological studies of identified long hair sensilla (LHS) have provided information on primary afferent fibre pathways in the ventral nerve cord of the Indian black scorpion, Heterometrus fulvipes.Cobalt-filling of single LHS on the metasoma showed that sensory axons enter the respective segmental ganglion, ascend ipsilaterally through the next anterior ganglia and terminate in a 4th ganglion. In each ganglion, these plurisegmental fibres give off collateral branches that terminate in the ganglionic neuropil. Fibres entering heterolateral connectives were not found.Recordings from peripheral nerves after deflections of a hair showed single or multiple spike discharges. A single spike could be recorded from ipsilateral anterior connectives of the ventral nerve cord, indicating a through-conductance of the sensory pathways. Strong deflections of a single hair activated several ipsilateral and fewer contralateral ascending interneurons and some segmentai motor neurons. Behavioral studies demonstrate the mechanoreceptive function of the LHS.The present study provides evidence in support of the notion that sensory afferents of the postabdomen in the scorpion bring about rapid, co-ordinated intersegmental movements of the multisegmented tail of the scorpion.Abbreviations CNS central nervous system - LHS long hair sensillum - TR trichobothria     

Central projections of campaniform sensilla on the cerci of crickets and cockroaches

Summary Campaniform sensilla associated with filiform hairs comprise an important receptor type of the multimodal sensory system of the cerci of crickets and cockroaches. Their axon projections were investigated using iontophoretic cobalt injection into single sensilla.In crickets (Gryllus bimaculatus, Acheta domestica), six different types of cereal campaniform sensilla projections can be distinguished on the basis of their axonal arborizations and terminations. Typically, a proportion of cereal campaniform sensilla, associated with long filiform hairs, give rise to axons that ascend as through fibres from the terminal ganglion to reach the sixth abdominal ganglion. Cereal campaniform sensilla associated with clavate hairs have projections restricted to the terminal ganglion alone.Whereas in crickets axons of cercal campaniform sensilla invade only certain segmental neuropils in the terminal ganglion, in cockroaches (Periplaneta americana) axons from cercal campaniform sensilla branch in every segmental neuropil. A proportion of cereal campaniform sensilla in this species also gives rise to through fibres to the fifth abdominal ganglion.We discuss morphological and functional interpretations of differences between crickets and cockroaches and consider the significance of this type of receptor in the context of previous studies of the cercal system.     

Coxal hair plates in spiders: physiology,fine structure,and specific central projections

Coxal hair-plate sensilla in the spider Cupiennius salei are described with respect to their innervation, central projection pattern, electrical response to mechanical stimulation, and putative behavioral function.

Advanced sub social behaviour in the scorpionHeterometrus fulvipes Brunner (Arachnida)

Scorpions arc generally non-social, solitary animals that interact with conspecifics at birth, courtship or predation only. The present study reports the presence of advanced sub social behaviour inHeterometrus fulvipes Brunner and evaluates the importance of its burrowing as a cause for such social behaviour.Heterometrus fulvipes constructed deep angular burrows at the base of plants. Burrows provided (i) protection against predation, (ii) increased availability of food and (iii) ideal microclimate for year round activity of the scorpions. No cannibalism was observed in laboratory maintained colonies. The risk of predation and the difficult by immatures to dig tunnels during dry soil conditions may have forced the mother and offspring to live together in the burrow for longer durations. The cohabitation of relative offsprings transforms the burrow into a nest. The members of a colony exhibits division of labour for nest expansion and in foraging. The mother communicates with the immatures through “Buzz” sound and may provide premasticated food. There is food sharing also among colony members. All these behaviours indicate the presence of advanced sub social behaviour inHeterometrus fulvipes.     

Fine structure and primary sensory projections of sensilla located in the sacculus of the antenna of Drosophila melanogaster

Sensilla lining the inner walls of the sacculus on the third antennal segment of Drosophila melanogaster were studied by light and transmission electron microscopy. The sacculus consists of three chambers: I, II and III. Inside each chamber morphologically distinct groups of sensilla having inflexible sockets were observed. Chamber I contains no-pore sensilla basiconica (np-SB). The lumen of all np-SB are innervated by two neurons, both resembling hygroreceptors. However, a few np-SB contain one additional neuron, presumed to be thermoreceptive. Chamber II houses no-pore sensilla coeloconica (np-SC). All np-SC are innervated by three neurons. The outer dendritic segments of two of these neurons fit tightly to the wall of the lumen and resemble hygroreceptor neurons. A third, more electron-dense sensory neuron, terminates at the base of the sensillum and resembles a thermoreceptor cell. Chamber III of the sacculus is divided into ventral and dorsal compartments, each housing morphologically distinct grooved sensilla (GS). The ventral compartment contains thick GS₁, and the dorsal compartment has slender sensilla GS₂. Ultrastructurally, both GS₁ and GS₂ are doublewalled sensilla with a longitudinal slit-channel system and are innervated by two neurons. The dendritic outer segment of one ofthe two neurons innervates the lumen of the GS and branches. On morphological criteria, we infer this neuron to be olfactory. The other sensory neuron is probably thermoreceptive. Thus, the sacculus in Drosophila has sensilla that are predominantly involved in hygroreception, thermoreception, and olfaction. We have traced the sensory projections of the neurons innervating the sacculus sensilla of chamber III using cobaltous lysine or ethanolic cobalt (II) chloride. The fibres project to the antennal lobes, and at least four glomeruli (VM₃, DA₃ and DL_2-3) are projection areas of sensory neurons from these sensilla. glomerulus DL₂ is a common target for the afferent fibres of the surface sensilla coeloconica and GS, whereas the VM₃, DA₃ and DL₃ glomeruli receive sensory fibres only from the GS.     

Central projections of the lagena (the third otolith endorgan of the inner ear) in the pigeon

Central projections of the lagena were studied in the pigeon using transport of biotinylated dextran amine (BDA) that was locally applied to the lagenar epithelium through the opened cochlear canal. Descending (dorsocaudal part) and superior (middle part) vestibular nuclei were the main rhombencephalon structures with the maximum density of labeled fibers and terminals. Lesser numbers of labeled fibers were observed in the ventral part of the lateral vestibular nucleus and also in the medial vestibular nucleus; single labeled fibers were found in the cochlear nuclei. In the cases where BDA diffused not only in the lagena but also on the basilar papilla after application of the marker to the cochlear canal, considerable numbers of labeled fibers were observed in the cochlear nuclei; apart from this, the pattern of distribution of labeled fibers in the vestibular nuclei did not differ in general from that described above (in the case of a sufficiently local application of BDA only to the lagena). Efferent lagenar neurons were localized ventrally with respect to the vestibular nuclei, in particular in the nucl. reticularis pontis caudalis. Neirofiziologiya/Neurophysiology, Vol. 40, No. 3, pp. 199–210, May–June, 2008.     

小菜蛾成虫下唇须感器的超微结构及其神经元中枢投射

【目的】明确小菜蛾Plutella xylostella成虫下唇须感器的形态结构及感器神经元的投射。【方法】利用光学显微镜观察和扫描电子显微镜观察下唇须结构和感器类型,利用神经回填技术和激光共聚焦显微镜观察下唇须感器神经元在脑部的投射。【结果】小菜蛾成虫下唇须共3节,其上存在Böhm氏鬃毛、钟形感器、鳞形感器、锥形感器、微毛形感器5种不同类型的感器和一个陷窝器结构。Böhm氏鬃毛短小尖细,钟形感器形如顶部凹陷的圆帽,两种感器均分布于下唇须第1节,且大小上均无雌雄二型差异;鳞形感器形同柳叶,锥形感器粗而直,均散生于下唇须的第2和3节,两种感器在大小上均存在雌雄二型差异,其中雌性的鳞形感器显著大于雄性的,根据其雌雄二型差异现象推测雌蛾的鳞形感器可能与感受寄主植物挥发物有关;下唇须第3节中上部具有一个圆形陷窝器结构,雄虫的陷窝器内径为5.68±0.33μm,雌虫的为6.03±0.23μm,雌雄间无显著性差异;凹坑内长有表面光滑的微毛形感器。小菜蛾下唇须感器神经元主要投射于脑部咽下神经节、每个触角叶的下唇须陷窝器神经纤维球和腹神经索3条通路。【结论】阐明了小菜蛾下唇须感器的类型、分布和形态特征及其感器神经元在脑部的投射形态,为深入了解小菜蛾下唇须感器的生理和功能奠定了基础。     

Development of antennal sensilla during moulting inNeomysis integer (Leach) (Crustacea,Mysidacea)

Summary The sensilla are associated with 6 enveloping cells. The innermost enveloping cell (e 1) secretes the dendritic sheath (=thecogen cell). All other enveloping cells are involved in the formation of the outer cuticular apparatus in secreting the cuticle of a definite region of the new hair shaft.The development of the new sensilla begins when an exuvial space expands between old cuticle and epithelium. The newly forming hair shafts lie folded back in an invagination of the epidermal tissue. Only a distal shaft part projects into the free exuvial space. The cuticle of the distal and middle shaft region is secreted by the three middle enveloping cells (e 2–e 4) (=trichogen cells), which are arranged around the dendritic sheath.The wall of the cylinder, in which the distal shaft is situated, is formed by the cuticle of the future proximal shaft region. It is secreted by the outer enveloping cells (e 5 and e 6). Furthermore, both enveloping cells form the hair socket (=trichogen-tormogen cells).The outer dendritic segments encased within a dendritic sheath run up through the newly formed hair shaft and continue to the old cuticular apparatus. The connection between sensory cells and old hair shaft is maintained until ecdysis. On ecdysis the old cuticle is shed and the newly formed shaft of the sensillum is everted like the invaginated finger of a glove. The dendritic sheath and the outer dendritic segments break off at the tip of the new hair shaft. Morphologically this moulting process ensures that the sensitivity of the receptors is maintained until ecdysis.The internal organization of the sensory cells shows no striking changes during the moulting cycle. An increased number of vesicles is accumulated distally within the inner dendritic segments and distributed throughout the outer segments of the dendrites. The cytoplasmic feature of the enveloping cells indicates that synthesis and release of substances for the cuticular apparatus of the new sensillum take place.     

Ultrastructure of the nerve cells and sensilla of Geocentrophora baltica (Platyhelminthes,Lecithoepitheliata) and the surface sensilla in the Geocentrophora group

Two types of nerve cell could be distinguished ultrastructurally in the central nervous system of Geocentrophora baltica (Prorhynchida, Lecithoepitheliata). Both show invaginations in the plasma membrane, but they differ in the character of the cytoplasm (light or densely stained) and the distribution of the neuronal vesicles (evenly or in groups). Different kinds of vesicles and neuronal release sites are observed. Special features of the synapses are pronounced local thickenings of the presynaptic membrane connected to paramembranous densities. In G. baltica and five endemic Geocentrophora spp. from Lake Baikal six types of surface sensillum were observed at the epidermal surface: 1. those with a long thin rootlet; 2. a short, balloon-shaped cilium with an aberrant axoneme and a reduced rootlet; 3. a rootlet branching into many striated bundles; 4. a thick rootlet; 5. a reduced rootlet and numerous neurotubules;and 6. collared sensilla each with one cilium in a deep pit surrounded by a collar of 11 to 12 microvilli. The variable number of microvilli in the collared sensillum is considered plesiomorphic relative to the stable number of eight microvilli known in sensilla of the Prolecithophora, Proseriata, and Rhabdocoela. The ultrastructure of the collar sensillum indicates that the Lecithoepitheliata is only distantly related to the Prolecithophora and higher turbellarians.     

Distribution and specific central projections of mechanoreceptors in the thorax and proximal leg joints of locusts

Summary Tactile hairs on the locust thorax can be divided into two classes by their external morphology and their central projection pattern: Short hairs, 10–100 m in length, which are assembled in distinct plates and rows, and long hairs, 100–800 m in length, which are distributed all over the body and are organized in large fields or aligned along the ridges of the appendages.The sensory fibers of the first class arborize in the lateral dorsal neuropile of thoracic ganglia and then extend further into the ipsilateral half of the corresponding ganglion in three main bundles from which fine rami of fibers end in the intermediate neuropile. In all three thoracic ganglia the projection pattern of homologous hair plates is similar.The sensory fibers of the second class exclusively terminate in special median ventral neuropiles, the ventral association center (VAC) and ventralmost ventral association center (VVAC). In addition fibers from meso- and metathoracic hairs, located close to the longitudinal midline of the animal, may terminate in the contralateral VAC and with one branch project to the next anterior ganglion through the ipsilateral connective. In contrast, fibers from prothoracic hairs were not found to leave their ganglion.With support by the DFG Neurale Mechanismen des VerhaltensSome of the studies were started at Universität Bielefeld, Fakultät für Biologie II (Abtlg. Prof. Dr. P. Görner)     

Structure and distribution of antennal sensilla in Oranmorpha guerinii (Gervais, 1837) (Diplopoda,Polydesmida)

Detailed information on sensory organs of Diplopoda especially on antennal sensilla are still sparse and fragmentary. The present study on the antennae of Oranmorpha guerinii (Polydesmida, Paradoxosomatidae) utilizing scanning electron microscopy revealed the presence of six sensillar types: (1) apical cones, (2) sensilla trichodea, (3) sensilla microtrichodea, (4) sensilla chaetica, (5) sensilla basiconica bacilliformia, and (6) sensilla basiconica spiniformia. External structure and distribution of cuticular antennal sensilla are compared with data from other diplopod species. We moreover discuss possible functions of antennal sensilla in millipedes.     

黄脊竹蝗触角感器的电镜扫描观察

黄脊竹蝗是中国南方地区重要的竹子害虫,为了更好地理解黄脊竹蝗"趋尿行为"的生理生化机制,通过电镜扫描技术研究了黄脊竹蝗成虫触角感器的类型、数量、形态及分布特征,比较分析了其在雌、雄成虫间的差异。结果表明:黄脊竹蝗雌、雄成虫触角丝状,由1节柄节、1节梗节和23节鞭节构成,雌雄间触角长度及直径差异不显著(P>0.05);雌、雄成虫触角感器均有毛形感器Ⅰ、毛形感器Ⅱ、刺形感器、锥形感器Ⅰ、锥形感器Ⅱ和腔锥形感器6种;其中,锥形感器数量最多,约占感器总数的53%,主要分布在鞭节的第8～21亚节上;各类感器在雌、雄成虫间触角上的分布特征相似,雄成虫触角上感器总数、锥形和腔锥形感器数量显著多于雌成虫(P<0.05)。     

霍氏啮小蜂外生殖器及其感器的超微结构

霍氏啮小蜂Tetrastichus howardi(Olliff)是许多鳞翅目害虫的群居性蛹寄生蜂。为分析霍氏啮小蜂成虫产卵器和交配器上与成虫产卵和交配有关的感受器类型,本文利用扫描电镜对霍氏啮小蜂成虫产卵器和交配器的超微结构进行了观察。在霍氏啮小蜂成虫产卵器上共发现了7种感受器,分别是毛形感器1(TS1)、毛形感器2(TS2)、刺形感器2(CH2)、分泌毛孔(SP)、栓锥形感器1(SS1)、栉齿状感器(DS)、浅凹形感器(SD)和火山形感器(VS)。交配器上共发现6种感受器官,分别是栓锥形感器2(SS2)、火山形感器(VS)、表皮孔(CP)、鸡冠状结构(Crs)、钟形感器(CAS)和毛形感器3(TS3)。结果表明霍氏啮小蜂可通过产卵器和交配器上感受器获得与寄主和配偶相关的信息,进而调控产卵行为和交配行为。     

前裂长管茧蜂触角感器的扫描电镜观察

前裂长管茧蜂是许多实蝇类害虫幼虫-蛹期的重要寄生性天敌。通过扫描电镜对其触角感受器进行超微观察,结果发现,前裂长管茧蜂雌蜂触角共发现7种感受器,分别为鳞型感器、Bhm毛、毛型感器、腔型感器、栓锥型感器、钟型感器及板型感器。其中,毛型感器具有3种形态(毛型感器Ⅰ、Ⅱ、Ⅲ),锥型感器具有2种形态(锥型感器Ⅰ、Ⅱ),但在雄蜂触角上没发现锥形感器Ⅱ。毛型感器和板型感器是前裂长管茧蜂触角上的主要感器,数量较多,分布较广。     

六斑月瓢虫触角及感觉器扫描电镜观察

[目的] 明确六斑月瓢虫雌雄成虫触角感觉器种类、分布及形态特征。[方法] 利用扫描电子显微镜对六斑月瓢虫雌、雄成虫触角形态及触角感受器超微结构进行观察。[结果] 六斑月瓢虫成虫触角由柄节、梗节和鞭节组成,柄节长度与宽度显著大于梗节长度与宽度;鞭节分为9个亚节,末端3节横向膨大呈锤状。雌雄成虫触角上共有8种感觉器:刺形感觉器(SC)、毛形感觉器(ST)、锥形感觉器(SB)、腔形感觉器(CaS)、钟形感觉器(CS)、哑铃形感觉器(DS)、香肠形感觉器(SS)及B?hm氏鬃毛感觉器(BB)。以毛形感觉器和刺形感觉器分布最广,遍布触角;B?hm氏鬃毛仅存在于触角柄节与梗节;触角鞭节第9亚节顶端密布7种触角感觉器。六斑月瓢虫雌雄成虫触角长度、触角感觉器类型及分布无显著差异。[结论] 六斑月瓢虫成虫触角上共有8种感觉器,其触角可能具有感知机械刺激、识别化学信息素及感受温湿度变化的作用。本研究为进一步了解六斑月瓢虫触角与其行为间的关系提供基础资料。     

角倍蚜 Schlechtendalia chinensis(Bell)(Hemiptera:Pemphigidae)各蚜型触角感器的比较分析

本研究利用扫描电镜对角倍蚜各蚜型触角感器的超微结构、类型、分布和数量进行了比较分析。结果表明,角倍蚜的触角上着生4种类型的感器：毛形感器、原生感觉圈、感觉突及次生感觉圈,它们在各蚜型触角上的分布和数量各不相同。其中,毛形感器有TypeⅠ和TypeⅡ两种类型,各蚜型触角上均有分布;原生感觉圈主要分布于干母、无翅干雌、第三代有翅干雌若蚜以及性蚜的触角上,有两种类型：PrⅠ和PrⅡ,分别位于触角的末节和倒数第二节,其中,第三代有翅干雌若蚜的触角上仅存在PrⅠ,无PrⅡ;感觉突仅出现于第三代有翅干雌若蚜触角的第3~5节;次生感觉圈仅存在于有翅型春迁蚜和秋迁蚜触角的第3~5节,其面积约占触角鞭节面积的2/3。我们认为,各蚜型触角感器的差异可能与蚜虫的生境（瘿内或瘿外）、行为（如取食、交配）以及翅的有无（如寄主选择、迁飞等）有关。     

Regeneration of the visual system in gastropods (Mollusca)

Abstract. The topic of tissue and organ regeneration has been of interest to life scientists ever since the phenomenon was noticed. The reason for this is obvious: if one can learn what drives and controls regeneration, i.e., how lost or damaged structures can be replaced, one not only has a better chance to understand an animal's embryogenesis and evolutionary relationship with other taxa, but one would also be in a better position to treat organ loss or tissue damage in humans. In this context, the possible restitution of individual sensory neurons or nerve projections has been of special interest to us. We identified central visual projections in several gastropod species and found that: (1) projections are very extensive across the brain and (2) they have connections with other systems and organs (including, most likely, non-ocular skin photoreceptors) that may be involved in the integration of signals from different sensors. Investigations of afferent and efferent visual elements at a morphological level should help reveal the neuronal basis of a gastropod's behavioral reactions.     

Ultrastructure of tarsal sensilla and other integument structures of two Pseudocellus species (Ricinulei, Arachnida)

Ricinuleids are one of the least investigated groups of Arachnida. In particular, knowledge of their ultrastructure is poor. Observations of the distal tarsomeres of ricinuleids show differences in their shape and equipment of surface structures. Legs I and II are used by the Ricinulei to explore their surroundings with tentative movements. The tarsomeres of these legs show similarities in shape and surface structures that distinguish them from those of legs III and IV. In this study, 11 different structures of the tarsomere surfaces of two cave-dwelling species, Pseudocellus pearsei and P. boneti from México, were investigated for the first time with scanning and transmission electron microscopy and discussed regarding their possible function: 1) a single treelike ramifying seta resembles a no pore single-walled (np-sw) sensillum; 2) setae occurring in a small number and possessing a bipartite shaft represent terminal pore single-walled (tp-sw) sensilla. The surface of the proximal half of the shaft shows small branches. The distal half has a smooth surface; 3) long setae with conspicuous longitudinal lamellae show characteristics of chemoreceptive wall pore single-walled (wp-sw) sensilla; 4) frequent small wp-sw sensilla with flat and irregular lamellae; 5) very short wp-sw sensilla occurring solitary or in groups; 6) a few short setae with smooth surface correspond to wp-sw sensilla; 7) a single short clubbed seta articulating in a flat pit is considered to be a np-sw sensillum; 8) common long setae with a pointed tip show characteristics of mechanoreceptive np-sw sensilla; 9) ventral setae with adhesive and mechanosensory function are accompanied by multicellular "class III" glands; 10) slit organs with mechanoreceptive function; and 11) dome-like tubercles with no indication of sensorial function. Several of these sensilla form a sensory field on the dorsofrontal surface which is particularly pronounced on the distal tarsomeres of legs I and II.     

拉步甲成虫触角感器的扫描电镜观察

利用扫描电子显微镜,观察了拉步甲Carabus lafossei成虫触角感器的类型、数量和分布规律。结果表明:拉步甲触角表面存在7类、12种感器类型,包括3种毛形感器(Sensilla trichodea,ST)、3种刺形感器(Sensilla chaetica,SCh)、2种锥形感器(Sensilla basiconca,SB)、Bhm氏鬃毛(Bhm bristles,BB)、腔锥形感器(Sensilla coeloconica,SCo)、腔形感器(Sensilla cavity,SCa)和钟形感器(Sensilla campaniformia,SCam),感器类型在雌、雄个体间无差异;雌、雄个体各节触角的感器数量和分布不均匀。研究结果为今后开展电生理学和行为生态学研究打下了基础。