Muscles and nerves of the posterior abdomen and genitalia of male Periplaneta americana (L.) (Dictyoptera : Blattidae)

Segmental and intersegmental muscles of abdominal segments 7–10 are described for adult, male Periplaneta americana (L.) (Dictyoptera : Blattidae). Locations of extrinsic and intrinsic genitalic muscles are documented, and the actions of those associated with the right phallomere are hypothesized. Muscles of the 5 abdominal segments are innervated by branches from 5 pairs of segmental nerves and 3 pairs of transverse nerves. These stem from a terminal synganglion, formed during embryogenesis by fusion of neuromeres of abdominal segments 7–11. One pair of segmental nerves issues from each of the 5 neuromeres, and one pair of transverse nerves arises from neuromeres of abdominal segments 7–9. The nerves are traced to the muscles, integument, and reproductive glands, and their peripheral unions are characterized. Serial homologies of the nerves and muscles are proposed, and comparisons are made with neuromusculature of the female.     

AN ANATOMICAL STUDY OF THE ABDOMINAL NERVOUS AND MUSCULAR SYSTEMS OF DRAGONFLY (AESHNIDAE) NYMPHS

The musculature of the fourth to eighth abdominal segments is typically composed of twenty pairs of segmental muscles associated with the body wall. In the first to third and ninth and tenth segments certain modifications to the basic plan occur in association with the abdominal-thoracic junction, the respiratory apparatus and the anal appendages. In some segments there are also paired muscles associated with the alimentary canal. Two large transverse muscles are present in the abdomen. There are eight abdominal ganglia, the first seven of which each give rise to three pairs of lateral nerves, the eighth to five pairs. In addition there are ten median abdominal nerves. The innervation fields of the various nerves are described. The first three pairs of lateral nerves of the last ganglion are homologous with the lateral nerves of the other abdominal ganglia; the fourth pair innervates most of segment nine; and the fifth pair innervates the remainder of segment nine, segment ten and the anal appendages. Certain of the abdominal muscles are innervated by branches from two different nerve roots. In segments six and seven the anterior point of attachment of the longitudinal stretch receptors is normally different from that in the other abdominal segments. This is discussed in the light of the types of movement which involve the abdomen and it seems apparent that these receptors are affected not only by swimming and abdominal flexion, as are the other longitudinal stretch receptors, but also by respiratory movements. Two distinct types of epidermal sensilla are present on the abdomen, spines and hairs. The former are the more numerous on the body, the latter on the anal appendages.     

Anatomy and innervation of the abdominal segmental muscles in larval and adult Tenebrio molitor (Coleoptera)

The external morphology, musculature, and the innervation of the abdominal segments were examined in larvae and adult Tenebrio molitor. In the larva, there are 26 pairs of muscles arranged at four different levels in the ventral, lateral, and dorsal region of each segment. In the adult, the number of muscles has been dramatically reduced and is limited to six pairs of muscles located at the dorsal and lateral region of the segment. These muscles, in either larval or adult stages, are innervated by two main nerves, n1 and n2, which originate from the segmental ganglia. The cell bodies of the motoneurons innervating the muscles of the 3rd abdominal segment are located in the 3rd and 2nd abdominal ganglia. Some cell bodies are retained throughout metamorphosis, but others disappear during the larva-pupa transition.     

Homeotic gene function in the muscles of Drosophila larvae

The segmental musculature of Drosophila melanogaster larvae consists of 24-30 muscles per segment. Unique patterns of muscles are found in the three thoracic segments and the first and last abdominal segments; the remaining abdominal segments share the same pattern. Mutations in Ultrabithorax (Ubx) cause partial transformation of the muscle pattern of larval abdominal segments towards metathorax. The muscles of the thorax are not affected. In the first two abdominal segments the changes include the loss of at least 11 `abdominal' muscles and the gain of 11 `thoracic' muscles. Less extensive transformations are seen in more posterior abdominal segments. Anterobithorax, bithorax, postbithorax and bithoraxoid mutations also induce transformations of the larval musculature. Each allelic group affects a domain that is a subset of the entire Ubx domain but these domains are not restricted to compartments or segments and may extend through as many as five segments. In the muscles the segmental distribution of Ubx antigen correlates with the segments affected by Ubx mutations. The different domains of Ubx in mesoderm and ectoderm argue that the segmental diversity of the muscle pattern is not simply induced by the overlying epidermis and that Ubx function in the mesoderm is required for the correct development of abdominal segments.     

Developmental and regional-specific expression of FLRFamide peptides in the tobacco hornworm,Manduca sexta,suggests functions at ecdysis

The developmental profile of a family of three FLRFamide (Phe-Leu-Arg-Phe-NH₂) peptides in the tobacco hornworm, Manduca sexta, revealed regional-specific expression patterns within the segmental ganglia. Levels of the three peptides—F7G (GNSFLRFamide), F7D (DPSFLRFamide), and F10 (pEDVVHSFLRFamide)—were always higher in the thoracic than abdominal ganglia. The predominant peptide also differed regionally, with F7G being highest in the thoracic ganglia and F7G and F10 being equivalent in the abdominal ganglia. Furthermore, we found regional-specific transient declines in ganglion peptide levels temporally correlated to ecdysis. Thoracic ganglion peptide levels declined at each molt, while abdominal ganglion levels declined over a period of 2 days after ecdysis. The decline in central levels was accompanied by an increase in levels in peripheral neurohemal sites, the transverse nerves (TNs). These observations suggest peptides were released from neurosecretory cells (NSCs) at ecdysis. Distinct sets of thoracic and abdominal NSCs and their processes in peripheral neurohemal sites were immunoreactive, supporting the biochemical data. These results also suggest the regional differences may arise from cellular-specific expression patterns for this family of peptides. In addition, fine immunoreactive processes were observed traveling between TNs and skeletal muscles, suggestive of myotropic actions. We propose that the release of different M. sexta FLRFamides from regionally distinct NSCs leads to a coordinated modulation of skeletal and visceral muscles that facilitate ecdysis. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 469–485, 1998     

Neurosecretory system of the American dog tick,Dermacentor variabilis (Acari: Ixodidae). II. Distribution of secretory cell types,axonal pathways and putative neurohemal-neuroendocrine associations; comparative histological and anatomical implications

Histological observations using specialized techniques reveal neurosecretory cells in 18 centers throughout the rind (cortex) of the central nerve mass or synganglion of Dermacentor variabilis. Many cells contribute to complicated networks of neurosecretory pathways and tracts in pre- and post-esophageal portions of the synganglion. The four types of neurohemal-neuroendocrine associations found in Dermacentor resemble structures found in soft ticks (Argasidae) and in other Arachnida, but are more diverse than those described from any other single species. Neurosecretory terminals are distributed diffusely and in two concentrated associations within the perineurium of the synganglion and major peripheral nerves. Terminals are also distributed in the perineurial layers of lateral segmental organs which lie in the general hemocoel at the level of the pedal nerves. A retrocerebral organ complex surrounds the esophagus at its junction with the midgut. The complex includes dorsal and ventro-lateral lobes (containing neurosecretory terminals and intrinsic secretory cells) and the proventricular (neurohemal) plexus. This plexus seems to be a modified (concentrated) cardioglial association. Cardioglial associations are also formed by the neurosecretory innervation of vascular walls of the dorsal aorta and circulatory sinuses which envelope the synganglion and major peripheral nerves. Inferential considerations of neurosecretory and endocrine interactions in the Acari are based on these anatomical and histological data which also provide the basis for evolutionary considerations of anatomical relationships and specializations in the neurosecretory systems of other Arachnida.     

Musculature, nervous system and glands of pregenital abdominal segments of the female of Nomia melanderi Ckll. (Hymenopters, Apoidea)

The gross anatomy of muscles, the topography of nerve tissues, and the histology of the pregenital abdominal glands of Nomia melanderi Ckll. are reported in detail. The movable and fixed points of muscle attachment were utilized in establishing a system of nomenclature for a typical abdominal segment. Names of nervules correspond to those of the tissues they innervate. The points of attachment of muscles of the fifth abdominal segment are essentially the same in both Nomia and Apis, except for the second tergo-sternal muscle which, in Nomia, has shifted its point of movable attachment to the membranous integument in front of the intersegmental membrane gland where it helps in relasing glandular secretion. The general plan of the nerves in the fifth abdominal segment in Nomia is more diffuse than in Apis, but there is no difficulty in establishing homology between the nervules of the two species. A pair of intersegmental stretch organs was found in abdominal segments 3–6. Glands of the sixth intersegmental membrane possess a reservoir with peripheral pouches both of which are absent in those of the fifth. Both types of glands have neither closing nor opening mechanisms, and neither is innervated. Release of glandular secretion is accomplished by the action of the tergo-sternal muscles.     

Synganglial and neurosecretory morphology of the chicken mite Dermanyssus gallinae (DeGeer) (Mesostigmata: Dermanyssidae)

Histological techniques and paraldehyde-fuchsin (PAF) staining were used to study the synganglion and to locate neurosecretory regions and neurosecretion within the synganglion of the chicken mite, Dermanyssus gallinae. The synganglion, which is formed internally by neuropilar ganglia, gives rise to a single esophageal and paired cheliceral, palpal, pedal (I-IV), and opisthosomal nerves. The neuropilar ganglia are interconnected by commissures and connectives within the synganglion. Twelve PAF-positive neurosecretory regions are present in unfed protonymphs, unfed deutonymphs, virgin males and females, and mated males. There are 11 PAF-positive neurosecretory regions in larvae, 24–72 hours post-fed deutonymphs and mated females. Neurosecretory regions in these developmental stadia are described in relation to their positions adjacent to individual neuropilar ganglia.     

Ultrastructure of the lateral organs in larvalArgas (Persicargas) arboreus (Ixodoidea: Argasidae)

The ultrastructure of lateral organs (LO) in the larval tickArgas (Persicargas) arboreus is described before and after feeding and up to the 1st day of moulting. Three pairs of LO are associated with three pedal nerves arising from the synganglion. In unfed ticks, each LO is ensheathed by a neural lamella and consists of 6–7 neuronal cell bodies; their cytoplasm is mostly occupied by cisternae of rough endoplasmic reticulm (RER). In fully engorged ticks, the enlarged neuronal cells contain vacuolar cisternae of smooth endoplasmic reticulum (SER), coated vesicles and mitochondria. Golgi bodies are involved in the formation of neurosecretory granules which dominate, with the SER vacuoles, the cell cytoplasm before moulting. The vacuoles, coated vesicles and neurosecretory granules are similar to those found in the vertebrate steroid-secreting cells. Condensing vacuoles may fuse with lysosome-like bodies to form larger ones; these are possibly responsible for the cell breakdown when secretory products are no longer required. Ultrastructural observations of LO suggest that they are neuroendocrine glands and that, in engorged larvae, they may secrete a hormone involved in the control of moulting.     

Skeletomuscular development of genital segments in the dragonfly Anax imperator (Odonata, Aeshnidae) during metamorphosis and its implications for the evolutionary morphology of the insect ovipositor

The skeleton-muscular organisation of abdominal segments 7-9 in female Anax imperator L. (Anisoptera, Aeshnidae) was examined in the stages of ultimate larva, teneral imago, and mature imago, with special emphasis on the transformation of the muscle arrangement. The absence of certain muscles in the genital segments compared to the 7th pre-genital segment was noted on all studied stages. Reductions of certain muscles in adults compared to those in larvae are reported. Some of ovipositor's muscles appear already in larvae. Attachment sites of larval muscles are retained in freshly emerged females concurrently with integument transformations. This situation allows for precise determination of the borders of newly differentiated genital sclerites and, therefore, of the possible origin of certain ovipositor elements in odonates. All changes in the segmental sets of studied abdominal muscles during metamorphosis are tabulated, and displacements of muscles are documented and illustrated. Schematic figures illustrating homologies between the parts of larval and imaginal abdominal sclerites are provided. The origins of the components of the endophytic ovipositor in Odonata as well as their implications for the evolutionary morphology of the insect ovipositor are discussed.     

Protodrilus (Protodrilidae, Annelida) from the southern and southeastern Brazilian coasts

Protodrilus corderoi, Protodrilus ovarium n. sp. and Protodrilus pythonius n. sp. are reported from beaches in southern and southeastern Brazil and described combining live observations with light and electron scanning microscopy studies. Protodrilus corderoi is redescribed from new collections at the type locality, and a neotype for the species is assigned since the original type material no longer exists. New information on reproductive organs, segmental adhesive glands and unpigmented ciliary receptors as well as morphometrics is provided. Protodrilus ovarium n. sp. and P. pythonius n. sp. are formally described. Protodrilus ovarium n. sp. is diagnosed by the presence of separated lateral organs on segments 7–12, three spermioducts of segments 10–12 and salivary glands in segments 1–9. Protodrilus pythonius n. sp. is defined by the presence of separated lateral organs on segments 7–16, long pygidial lobes and body tapering toward the pygidium. The distribution of the different species in more or less spacious habitats seems to be correlated with their gross morphology. Protodrilus pythonius n. sp., with relatively long and wide body and long palps with ciliary bands, was collected in very coarse sandy sediments at a reflective sheltered beach. Conversely, P. corderoi and P. ovarium n. sp., both possessing more slender bodies with shorter, less ciliated palps, occurred in medium-coarse, well-sorted sediments in the more energetic swash zone of exposed intermediate-reflective beaches. The finding of P. pythonius and P. corderoi in nearby beaches corroborates other studies showing a higher morphological variability among species in different habitats within the same geographical area than among species in the same habitat in different geographical areas.     

Identification of a complex peptidergic neuroendocrine network in the hard tick, <Emphasis Type="Italic">Rhipicephalus appendiculatus</Emphasis>

Neuropeptides are crucial regulators of development and various physiological functions but little is known about their identity, expression and function in vectors of pathogens causing serious diseases, such as ticks. Therefore, we have used antibodies against multiple insect and crustacean neuropeptides to reveal the presence of these bioactive molecules in peptidergic neurons and cells of the ixodid tick Rhipicephalus appendiculatus. These antibodies have detected 15 different immunoreactive compounds expressed in specific central and peripheral neurons associated with the synganglion. Most central neurons arborize in distinct areas of the neuropile or the putative neurohaemal periganglionic sheath of the synganglion. Several large identified neurons in the synganglion project multiple processes through peripheral nerves to form elaborate axonal arborizations on the surface of salivary glands or to terminate in the lateral segmental organs (LSO). Additional neuropeptide immunoreactivity has been observed in intrinsic secretory cells of the LSO. We have also identified two novel clusters of peripheral neurons embedded in the cheliceral and paraspiracular nerves. These neurons project branching axons into the synganglion and into the periphery. Our study has thus revealed a complex network of central and peripheral peptidergic neurons, putative neurohaemal and neuromodulatory structures and endocrine cells in the tick comparable with those found in insect and crustacean neuroendocrine systems. Strong specific staining with a large variety of antibodies also indicates that the tick nervous system and adjacent secretory organs are rich sources of diverse neuropeptides related to those identified in insects, crustaceans or even vertebrates. This work was supported by Slovak grant agencies: Agentúra na podporu vyskumu a vyvoja (APVV-51-039105) and Vedecká grantová agentúra (VEGA 2-6090-26 and 2/6155/26).     

Structure and anatomical relationships of the synganglion in the American dog tick,Dermacentor variabilis (Acari: Ixodiadae)

The synganglion of Dermacentor variabilis Say is a single nerve mass, condensed around the esophagus and within the periganglionic sinus of the ciculatory system. Protocerebral, cheliceral (including stomodeal bridge), and pedipalpal ganglia lie in the pre-esophageal portion of the nerve mass and bear optic, cheliceral, and pedipalpal nerves respectively. The unpaired stomodeal and the recurrent nerve which forms the hyper-esophageal ganglion arise from the stomodeal bridge. Paired primary and accessory nerves to the retrocerebral organ complex have mixed protocerebral-cheliceral origins. Pedal ganglia (including ventral olfactory lobes of pedal ganglia I) and composite opisthosomal ganglion lie in the post-esophageal nerve mass and bear pedal nerve trunks and two pairs of opisthosomal nerves respectively. Internally, the synganglion consists of cellular rind and fibrous core. A welldefined neurilemma with a laminar matrix covers nerve mass and peripheral nerves. The rind contains the somata of ganglionic neurons and ensheathing glial cells and is restricted to the synganglion mass. It is limited by two specialized glial layers, the external perineurium and internal subperineurium. Discrete glomerular formations are present within the protocerebrum and olfactory lobes. Olfactory glomeruli located in pedal ganglia I are associated with a pair of globuli cell groups. Possible physiological relationships between anatomical specializations of the synganglion, extraneural sinuses and circulating hemocytes are considered. The evolutionary significances of condensation in the stomatogastric neuropile regions and throughout the synganglion, together with the simplification and loss of glomerular formations, are discussed.     

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 anatomy of the adult uropodid Fuscouropoda agitans (Arachnida; Acari), with comparative observations on other Acari

A thin, compressible, lateral suture and ventral plate overlap permit limited movement of the thick and rigid dorsal and ventral plates of Fuscouropoda agitans. Seven pairs of large dermal glands debouch onto the surface. Trochanteral rotation permits defensive leg adpresion and an insectan type of ambulation. The complex hypopharynx-pedipalpal-coxae has a buccal and cheliceral cavity separated by an atriculated epipharynx. The pharynx is Y-shaped in cross section. Extensive paired salivary glands lie above the very long and dexterous 3-segmented chelicerae, and a large pair of coxal glands debouch on coxae 1. From four blunt-ended tracheae, bundles of unbranching tracheoles extend in specific tracts to all organs. The ventriculus is small with three pairs of large caeca; a tightly packed single layer of digestive cells individually enlarged to absorb-phagocytize and digest the food. A typical mesostigmatid excretory tube is present. A typical acarine synganglion is present; mixed nerves have a basal swelling. A postulated neurosecretory organ arises from the pedipalpal nerve. The oocytes enlarge within funicular stalks from the walls of the small median ovary. A large spermatophore is stored in the seminal vesicle; fertilization occurs during oviposition. A tension hinge partially opens both male and female genital plates; closure effected by muscles acting on very long genital plate apodemes. Within sequentially produced spermatogonial cysts of the testes, meiosis is completely synchronous. A large, multilobed male accessory gland produces a large volume of seminal fluid; a mixture of at least four secretions. The origins and msertions of the body wall, genital organ, digestive tract, mouthpart and leg muscles are listed and illustrated. A comparison of anactinotrichid and actinotrichid mites indicates fundamental and consistent morphological differences in aspects of the cuticle, leg articulations, digestive system, excretory system, reproductive system and coxal glands.     

Comparative anatomy of muscle sets in larval and adult stages ofZophobas morio (Coleoptera,Tenebrionidae)

Summary The muscles of the metathoracic segment are described for the larva and imago of the beetleZophobas morio. In the search for possible homonomous and ontogenetic persistent structures, we further employed muscles served by the first segmental nerve in the thoracic and abdominal segments. In the larva, eight muscles per hemisegment are associated with this nerve. Based on topological criteria they may be characterized as homonomous for all tested segments. In the adult, the topology of the dorsal muscles seems to be different compared to the larval situation, due to the complex structural remodelling during metamorphosis. However, a supplementary analysis employing the innervation pattern allows us to equate larval with adult muscles, even down to the level of individual motor units. Comparison of different orthopteran and coleopteran species provides some evidence that these muscles are homologous, apparently representing part of a basic pattern common in pterygote insects.     

Three-dimensional reconstruction of the musculature of Cossura pygodactylata Jones, 1956 (Annelida: Cossuridae)

The musculature of adult specimens of Cossura pygodactylata was studied by means of F-actin labelling and confocal laser scanning microscopy (CLSM). Their body wall is comprised of five longitudinal muscle bands: two dorsal, two ventral and one ventromedial. Complete circular fibres are found only in the abdominal region, and they are developed only on the border of the segments. Thoracic and posterior body regions contain only transverse fibres ending near the ventral longitudinal bands. Almost-complete rings of transverse muscles, with gaps on the dorsal and ventral sides, surround the terminal part of the pygidium. Four longitudinal bands go to the middle of the prostomium and 5–14 paired dorso-ventral muscle fibres arise in its distal part. Each buccal tentacle contains one thick and two thin longitudinal muscle filaments; thick muscle fibres from all tentacles merge, forming left and right tentacle protractors rooted in the dorsal longitudinal bands of the body wall. The circumbuccal complex includes well-developed upper and lower lips. These lips contain an outer layer of transverse fibres, and the lower lip also contains inner oblique muscles going to the dorsal longitudinal bands. The branchial filament contains two longitudinal muscle fibres that do not connect with the body musculature. The parapodial complex includes strong intersegmental and segmental oblique muscles in the thoracic region only; chaetal retractors, protractors and muscles of the body wall are present in all body regions. Muscle fibres are developed in the dorsal and ventral mesenteries. One semi-circular fibre is developed on the border of each segment and is most likely embedded in the dissepiment. The intestine has thin circular fibres along its full length. The dorsal blood vessel has strong muscle fibres that cover its anterior part, which is called the heart. It consists of short longitudinal elements forming regular rings and inner partitions. The musculature of C. pygodactylata includes some elements that are homologous with similar muscular components in other polychaetes (i.e., the body wall and most parapodial muscles) and several unique features, mostly at the anterior end.     

Structure of female genitalia of glassy-winged sharpshooter, Homalodisca coagulata (Say) (Hemiptera: Cicadellidae)

The functional reproductive morphology of the female glassy-winged sharpshooter, Homalodisca coagulata (Say), is described at both light microscopy and scanning electron microscopy levels. The female has nine abdominal segments; the seventh to the ninth abdominal segments are modified for reproduction; the eighth tergite is reduced to two segments, with the ovipositor partially exposed from the modified ninth segment-the pygofer. The pygofer, covered with trichoid and coeloconic sensilla, almost completely encloses the ovipositor, which consists of three pairs of valvulae and two pairs of valvifers. The first and second valvulae function together for oviposition. The first valvulae are located exterior to the second valvulae, both of which bear many trichoid, campaniform, and coeloconic sensilla. The third valvulae, possessing many coeloconic sensilla, envelope the first and second valvulae. Seven major muscles are found to be associated with the ovipositor and the pygofer. The oviposition process is described with respect to the activity of the valvulae and their associated musculature. The female morphology follows the general pattern of cicadellids as a group.