Showing papers in "International Journal of Insect Morphology & Embryology in 1989"
TL;DR: A model of the 3-dimensional structure of the antennal lobes in the brain of the worker honey bee, Apis mellifera L. (Hymenoptera : Apidae), has been constructed using retrograde cellular marking and computer reconstruction techniques and provides a pictorial representation of the spatial organization of structures within the antenNal lobe neuropil.
Abstract: A model of the 3-dimensional structure of the antennal lobes in the brain of the worker honey bee, Apis mellifera L. (Hymenoptera : Apidae), has been constructed using retrograde cellular marking and computer reconstruction techniques. The model provides a pictorial representation of the spatial organization of structures within the antennal lobe neuropil. In addition, an atlas is provided to aid the identification of invariant morphological landmarks within the antennal lobe, some of which have been described previously. Readily identifiable invariant glomeruli are described in detail, and a hitherto unreported afferent tract of the antennal nerve, the tract “T2-2”, is also identified. Precise descriptions of the arborizations patterns of several deutocerebral interneurones stained intracellularly with cobalt serve to illustrate the advantages of using the atlas and 3-dimensional representations of the antennal lobe represented in this paper.
172 citations
TL;DR: Scanning electron microscopy was used to elucidate the morphology and sequential movement of thrips feeding structures in the 2 species, Frankliniella occidentalis and F. schultzei, and suggests that thrips be classified as piercing-sucking rather than rasping-sucker insects.
Abstract: Scanning electron microscopy was used to elucidate the morphology and sequential movement of thrips feeding structures in the 2 species, Frankliniella occidentalis and F. schultzei, (Thysanoptera : Thripidae). The mouthcone consists of paired paraglossae, and fringed labral pad, a single, apically fused mandible and a pair of interlocking maxillae. The maxillae are open apically and form a feeding tube. Ten pairs of sensory pegs of 3 distinct morphological types (sensilla basiconica with a cuticular collar, sensilla basiconica without a cuticular collar, and sensilla trichoidea) were found on the paraglossae. The possible function of these sensory structures in host finding and choice are discussed. No structure for rasping the leaf's surface was found on the mouthcone or the ventral surface of the insect. Live specimens were observed feeding through Parafilm on artificial media (sucrose solution) and lettuce leaf tissue. These observations support earlier findings that thrips feed by piercing leaf cells with the mandible and ingesting cell contents through the feeding tube formed by the maxillary stylets. Based on these findings, we suggest that thrips be classified as piercing-sucking rather than rasping-sucking insects.
79 citations
TL;DR: The internal morphology of the western flower thrips, Frankliniella occidentalis (Pergande) (WFT), a primary vector of tomato spotted wilt virus (TSWV), was shown to bear certain similarities to other thrips species, particularly in the composition of the piercing-sucking feeding structures.
Abstract: The internal morphology of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae) (WFT), a primary vector of tomato spotted wilt virus (TSWV), was shown to bear certain similarities to other thrips species, particularly in the composition of the piercing-sucking feeding structures. Striking differences were observed in number, position and ducting of the salivary glands, the morphology of the alimentary canal and the number and arrangement of the malpighian tubules between the WFT and other studied Thysanopterans. These differences provide support for the conclusion that internal morphologies may vary widely in this order, and perhaps among species in the same genus. The results of our investigation support the need for more detailed studies of other thrips species, particularly in light of the potential importance morphological characteristics may play in governing the capacity of thrips species to serve as vectors of TSWV.
63 citations
TL;DR: There are fewer sensilla in the A3 groups than in other gomphocerine grasshoppers, and the possibility that this is related to host-plant specificity is discussed.
Abstract: Bootettix argentatus (Orthoptera : Acrididae) is a monophagous grasshopper in the subfamily Gomphocerinae. The numbers of chemoreceptors in most groups on the mouthparts increase with each molt and are generally similar in the 2 sexes. There are fewer sensilla in the A3 groups than in other gomphocerine grasshoppers, and the possibility that this is related to host-plant specificity is discussed. Only very small numbers of sensilla are present on the pulvillar pads of the tarsi and on the arolia. The number of sensilla on the antennae is proportional to the length of the flagellum and coeloconic sensilla comprise 30–35%. Most of the remainder are multiporous basiconic sensilla. Adult males have more antennal sensilla than adult females.
25 citations
TL;DR: Scanning electron microscopy and immunohistochemical staining for FMRFamide-like peptides revealed that the stomatogastric nervous system of Galleria mellonella includes 5 ganglia: the frontal ganglion with 4, the hypocerebral ganglions with 2, the ingluvial gangLion with 2–4, and each of the paired proventricular ganglia with 6–8 immunoreactive perikarya.
Abstract: Scanning electron microscopy and immunohistochemical staining for FMRFamide-like peptides revealed that the stomatogastric nervous system of Galleria mellonella (Lepidoptera : Pyralidae) includes 5 ganglia: the frontal ganglion with 4, the hypocerebral ganglion with 2, the ingluvial ganglion with 2–4, and each of the paired proventricular ganglia with 6–8 immunoreactive perikarya. Immunoreactivity was also found in axons to and within the corpora cardiaca, in the nerves connecting stomatogastric ganglia, as well as in 8 gastric nerves that extend along longitudinal midgut muscles. Adhesion of corpora cardiaca to the hypocerebral ganglion and partial merging and shortening of gastric nerves were the only conspicuous changes of the stomatogastric system that occurred during metamorphosis.
22 citations
TL;DR: The spermathecae of 4 species of Microcoryphia present characteristics related to the primitive phylogenetic position of these apterygote insects, including paired organs situated in the 8th abdominal segment on each side of the rudimentary genital chamber.
Abstract: The spermathecae of 4 species of Microcoryphia (Lepismachilis targionii, Trigoniophthalmus alternatus, Machilis sp. and Machilinus rupestris) present characteristics related to the primitive phylogenetic position of these apterygote insects. They are paired organs situated in the 8th abdominal segment on each side of the rudimentary genital chamber. Each spermatheca includes 2 different tissues: (a) a simple epithelium surrounding 2 spermathecal capsules and communicating with the genital chamber by short ducts; (b) a complex glandular tissue composed of numerous functional units, each made up of several cell types — a large glandular cell with a subapical reservoir, 2 basal cells, a ductule cell and enveloping cells. One of the basal cells, called the ciliary cell, presents a dendrite-like process containing 2 apical centrioles in alignment. Several ductules of neighbouring units join together before opening in the genital chamber, independently of the ducts of the spermathecal capsules. The spermathecae undergo marked changes during moulting periods. Apolysis is followed by a partial dedifferentiation of the glandular cells, then the formation of new ductule cavities and the growth of a pseudocilium at the apex of the dendrite-like process of each ciliary cell. Afterwards, cuticular material is laid down around the pseudocilia, forming the intima of the new ductules, which results from the secretions of at least the ciliary and ductule cells. The pseudocilia degenerate before ecdysis. A comparison is made with the organogenesis of analogous organs described in different insect species.
16 citations
TL;DR: Neither micropyles nor aeropyles were observed in either proturan or collembolan eggs.
Abstract: The eggs of one proturan and two representatives of Collembola ( Heteromurus nitidus and Hypogastrura succinea ) were studied by scanning and transmission electron microscopy. The proturan ( Eosentomon ) eggs are covered by 2 envelopes. The surface of the outer one is equipped with numerous hemispherical projections. The eggs of H. nitidus possess an envelope, which is studded with numerous granules. In H. succinea , eggs are covered with 2 envelopes. The outer is studded with characteristic complex structures. Neither micropyles nor aeropyles were observed in either proturan or collembolan eggs.
16 citations
TL;DR: A scheme has been developed for the functional morphology of the pretarsus of the honeybee, and a series of pedal mechanisms are suggested that include the sensory (chemo- and mechano-) functions of the tarsal setae.
Abstract: The pretarsus of the honeybee, Apis mellifera (Hymenoptera: Apidae) (all castes) was examined with light and scanning electron microscopy (SEM). It is a 7-part structure, consisting of (from distal to proximal) ungues, arcus, arolium, planta, manubrium, unguitractor and tarsomere 5. A detailed study of these structures is of great interest, based on the behavior facilitated by it, and because it is likely an area for the ingress of pesticides. Following a description of overall topographical fine structure, a scheme has been developed for the functional morphology of the pretarsus. Particular attention has been paid to the pretarsal setae and cuticular relief of the plantar surfaces of the pretarsal sclerites. Based on our findings a series of pedal mechanisms are suggested that include the sensory (chemo- and mechano-) functions of the tarsal setae. The latter's afferent information drives effector deployment of the 7-component foot as these sequentially contact the substratum.
15 citations
TL;DR: The appearance of an increasing number of lysosome-like bodies in the cytoplasm suggests that juvenile hormone activates the lysozymes, which leads to the degeneration of the hypopharyngeal glands.
Abstract: In the fully activated hypopharyngeal gland of the worker honeybee, Apis mellifera (Hymenoptera : Apidae), there were numerous electron-dense secretion granules, large secretion masses, free ribosomes, and arrays of endoplasmic reticulum. Injection of juvenile hormone into the honeybee caused crystallization of the secretion granules. After 1 and 7 days following the injection, both free and attached ribosomes were depleted from the cytoplasm. The depletion of ribosomes from the cytoplasm of the hypopharyngeal gland cells was observed only in honeybees infected by Nosema apis after injection of juvenile hormone. The appearance of an increasing number of lysosome-like bodies in the cytoplasm suggests that juvenile hormone activates the lysozymes, which leads to the degeneration of the hypopharyngeal glands.
14 citations
TL;DR: Egg morphology promoting vertebrate host contact and aerodynamic design of the egg are both discussed, and enzymatic activity successfully separated egg from egg for the first time.
Abstract: Attachment of the eggs of the human bot fly, Dermatobia hominis (L. Jr.) (Diptera : Cuterebridae) to zoophilic insects is vital for the parasites dispersal and initial host contact. Eggs of D. hominis taken from carrier insects were examined with light and scanning electron microscopy. Egg structure and the means by which eggs remain attached to carrier insects was determined. The eggs are soft-shelled, curved dorsally and flattened ventrally. A polygonal pattern is found on the chorion surface. Walls of the eggs are layered and greatly thinned ventrally. Attachment of eggs occurs between each other (as an egg mass) and to the carrier insect. Both manners of attachment combine to increase rigidity of the egg mass. Egg-to-carrier attachment remains strong for decades and is effected by a highly infiltrative cement 15–20 μm thick beneath the posterior 1 4 of the egg mass. Egg mass removal ruptures setae and/or scales from the carrier. Egg-to-egg attachment is very effective. A distinct adhesive layer is absent among eggs. Rupture of wall(s) occurs when one egg is pulled from another. Enzymatic activity successfully separated egg from egg for the first time. Egg morphology promoting vertebrate host contact and aerodynamic design of the egg are both discussed.
13 citations
TL;DR: The Malpighian tubules of nymphal Aeshna cyanea (Odonata : Aeshnidae) were examined by light and electron microscopy and revealed an elaborate cytoskeleton and multiple adhesive junctions of the accompanying trachea, the basal lamina and the tubule cells.
Abstract: The Malpighian tubules of nymphal Aeshna cyanea (Odonata : Aeshnidae) were examined by light and electron microscopy. The 1st-instar nymphs have only 3 branchless tubules. With proceeding nymphal stages, these lengthen and branch. Also, additional tubules bud from the gut and show the same pattern of growth and branching, until in the final instar up to 21 separate tufts of branched tubules are present. A serpentine trachea/tracheole and a cross-striated muscle are helically wound around each tubule in close apposition. Isolated tubules show twisting movements for several days. Contraction of the muscle is responsible for fast coiling movements, while the slow decoiling movements probably depend on elastic deformations of the accompanying trachea, the basal lamina and the tubule cells, the latter showing an elaborate cytoskeleton and multiple adhesive junctions. The tubular epithelium consists of 4 types of cells. The distal segment is composed of ion transporting cells and terminates with a short, solid tip segment of undifferentiated cells. The intermediate segment consists of lipid cells which are densely filled with triglyceride droplets, as revealed by thin layer chromatography. Lipid cells are already present in the 1st instar before the nymphs have taken up any food. In later instars, the renal lipid content varies to some extent with the nutritional state and is nearly depleted during metamorphosis. The proximal segment is the region of tubular branching and may be conceived as the collecting duct of each tuft. Its epithelium consists of mucocytes.
TL;DR: The fine structure of the midgut, pyloric region, Malpighian papillae, and hindgut of Sinentomon erythranum (Protura : Sinentomidae) is described and the findings are compared with the gut organization of other genera of Protura examined to date.
Abstract: The fine structure of the midgut, pyloric region, Malpighian papillae, and hindgut of Sinentomon erythranum (Protura : Sinentomidae) is described. Midgut cells are rich in mineral concretions and are presumably involved in excretory activity; the pyloric chamber, a cavity in the proturan intestine behind the midgut, is formed by cells with microvilli pointing anteriorly; the secretion from 6 Malpighian papillae flows into this cavity. The hindgut consists of 2 regions; the anterior of the 2 has a series of specializations typical of cells engaged in active water reabsorption. Long infoldings of the apical plasma membrane reach deep into the cells. The findings are compared with the gut organization of other genera of Protura examined to date.
TL;DR: The structural associations of brain components with each other and the subesophageal ganglion, as well as the paths of the major nerve tracts in male A. aegypti are described and compared with those in other Diptera.
Abstract: The brain and subesophageal ganglion of male Aedes aegypti (L.) (Diptera : Culicidae) are described from cryofractures and silver-stained, semithin (0.5 μm) serial sections of whole heads observed in the scanning and light microscopes. The brain and subesophageal ganglion of male A. aegypti are fused. The major structures of the brain include the protocerebral lobes and bridge, the mushroom bodies, central complex of the protocerebrum, the mechanosensory regions and olfactory loves of the deutocerebrum, and the tritocerebrum. Major commissures of the brain are the anterior optic tract, central commissure, posterior dorsal commissure, and subesophageal commissure. The structural associations of brain components with each other and the subesophageal ganglion, as well as the paths of the major nerve tracts in male A. aegypti are described and compared with those in other Diptera.
TL;DR: Observations suggested that CsV-induced degeneration is specific to the host's prothoracic glands, which is in contrast to control tissues which showed no signs of ultrastructural degeneration or gross abnormalities as compared with control tissues.
Abstract: Campoletis sonorensis (Cameron) (Hymenoptera: Ichneumonidae) is a solitary endoparasitoid of Heliothis virescens . The lateral oviducts of the female parasitoid contain a particulate suspension called calyx fluid. The particles in calyx fluid are a polydnavirus (CsV) which, when injected into last-instar H. virescens , stimulates degeneration of the host's prothoracic glands. In order to determine if CsV-induced degeneration is specific to prothoracic glands, last-instar H. virescens larvae were injected with C. sonorensis calyx fluid. After 4 days, a variety of host tissues were dissected from both calyx fluid-injected and uninjected control larvae and fixed for transmission electron microscopy. Prothoracic glands from injected larvae were ultrastructurally degenerated by 4 days post-injection, whereas control glands remained intact. Other tissues from calyx fluid-injected larvae (tracheal epithelia, corpora allata, Malpighian tubules, fat body, skeletal muscle, and the brain) showed no signs of ultrastructural degeneration or gross abnormalities as compared with control tissues. These observations suggested that CsV-induced degeneration is specific to the host's prothoracic glands.
TL;DR: In queens aged from 18 to 24 months, the Reduction of pheromonal and secretory activities is associated with the reduction of mitochondrial population as well as with the accumulation of lipid droplets and various lytic structures.
Abstract: Each mandibular gland of the queen bee, Apis mellifera L. (Hymenoptera: Apidae) consists of an axial cavity lined with a thin cuticular intima, secreted by a flat epithelium, and numerous glandular units (type 3), each unit with one duct cell and a large polyploid glandular cell. Mitochondria and endoplasmic reticulum are preponderant organelles. During the ontogeny of the queen bee, the ultrastructure of the glandular cells evolves as her level of pheromonal activity. Variations mainly concern the mitochondrial system. Hence, at the beginning of the imaginal life, the homogeneous population of small mitochondria increases. Towards the 3rd–5th day of the queen's imaginal life, the pheromonal activity increases and the mitochondrial differentiation results in the appearance of giant forms. During the highest activity phase (6 to 18-month-old queens), giant mitochondria, associated with endoplasmic reticulum, invade cytoplasmic areas. In queens aged from 18 to 24 months, the reduction of pheromonal and secretory activities is associated with the reduction of mitochondrial population as well as with the accumulation of lipid droplets and various lytic structures.
TL;DR: In the germaria of oviparae of the vetch aphid, Megoura viciae Buckton (Homoptera : Aphididae), the trophocytes are syncytial and arranged around a trophic core, to which they are all joined.
Abstract: In the germaria of oviparae of the vetch aphid, Megoura viciae Buckton (Homoptera : Aphididae), the trophocytes are syncytial and arranged around a trophic core, to which they are all joined. Resting oocytes occur in the posterior region of the germaria, and encircle the basal region of the nutritive cord. The trophocytes contain mitochondria, ribosomes, vesicles, electron-dense spheres and a single large nucleus that is highly lobed and has many nucleopores. Electron-dense, “nuage-like” materials are confluent between nucleoplasm and cytoplasm, suggesting nucleocytoplasmic transport. Exterior to the trophocytes, a unicellular sheath surrounds each germarium, bordered to the exterior by a tunica propria. The cells of the sheath are continuous with the prefollicular tissue. Only one oocyte in each ovariole undergoes vitellogenesis at a time.
TL;DR: The stemmata of the first-instar larvae of Mantispa sp.
Abstract: The stemmata of the first-instar larvae of Mantispa sp. (Neuroptera) were studied by scanning (SEM) and transmission (TEM) electron microscopy. These preparasitic larvae have a pair of anterior eyes and a single posterior eye on each side of the head. Each eye possesses an outer lens; beneath it, there is a well-developed crystalline body and a 3-tiered retina made up of a maximum of 12 sensory cells. The central fused rhabdom appears always to be composed of 4 sensory cells, each filled with pigment granules. The nuclear region shows Golgi bodies and abundant rough endoplasmic reticulum; the rhabdomeric regions contain vesicles, prominent multi-vesicular bodies and lysosomes. The eyes, whether double or single, are surrounded by a perineurium, to which muscle cells are attached.
TL;DR: The radial fine structure of the eggshells of all 3 species as well as of alcohol-stored eggs of Mnesarchaea acuta (Mnesarchaeidae) is basically identical to the egg shell of Korscheltellus lupulinus (Hepialidae).
Abstract: The eggshells of Hepialus hecta, Wiseana umbraculata (Hepialidae) and of Mnesarchaea fusilella (Mnesarchaeidae) (Lepidoptera, Exoporia) were studied by scanning electron microscopy (SEM) and transmission (TEM) electron microscopy. All 3 species show a very similar surface sculpture of the micropylar region which, however, is very different from the eggs of the Ditrysia. The micropylar plate is large and oval. There are only 2 or 3 micropylar openings. In the hepialid moths, the surface of the egg's main body is characterized by spherical protuberances. The radial fine structure of the eggshells of all 3 species as well as of alcohol-stored eggs of Mnesarchaea acuta (Mnesarchaeidae) is basically identical to the eggshell of Korscheltellus lupulinus (Hepialidae). The chorion consists of only one layer, which, in the hepialid species, shows a crystalline-like fine structure. The vitelline envelope is composed of a thin, laminated, outer layer (V-2) and a thick, rigid, inner layer (V-1) that is traversed by large numbers of canals. This kind of eggshell architecture is distinctively different from that of the ditrysian Lepidoptera.
TL;DR: The eggs of Tinea pallescentella Stainton, Tinea occidentella Chambers, and Niditinea fuscella (L.) (Lepidoptera : Tineidae) were studied by scanning electron microscopy and much of the surface shows a porous texture.
Abstract: The eggs of Tinea pallescentella Stainton, Tinea occidentella Chambers, and Niditinea fuscella (L.) (Lepidoptera : Tineidae) were studied by scanning electron microscopy. Eggs of P T. pallescentella are subcylindrical (0.64 × 0.33 mm) and marked by a reticulate pattern of polygonal cells overlain cells by a finer reticulum of minute, closely spaced sinuous ridges or carinae. Eggs of T. occidentella are subcylindrical (0.62 × 0.36 mm) and marked by a reticulate pattern of polygons, which is faint except on the anterior end, where the cells are outlined by ruffled carinae. The surface of the chorion is wrinkled, and the micropylar area is often raised, forming a nipple on the anterior end. Eggs of N. fuscella are subcylindrical or occasionally ellipsoid (0.45 × 0.28 mm) and marked by a bold pattern of strongly depressed polygonal cells outlined by heavy ridges. The cell discs of the anterior end are punctuated by numerous short carinae, some of which extend transversely over the surrounding ridges. At high magnification, much of the surface shows a porous texture.
TL;DR: The eggs and supporting stalks of one Campodea (Apterygota : Campodeidae) species were studied by scanning and transmission electron microscopes and found that each egg batch is attached to the substrate by a supporting stalk that is strongly PAS-positive.
Abstract: The eggs and supporting stalks of one Campodea (Apterygota : Campodeidae) species were studied by scanning and transmission electron microscopes. Each egg batch is attached to the substrate by a supporting stalk. The stalk is composed of tangled lamellae and dense annular structures. Both elements are strongly PAS-positive. The eggs are covered by one envelope only. It is built of fine granular, PAS-negative material. The surface of the envelope is smooth and possesses 2–4 ring-like structures, which are likely involved in the attachment of the eggs within a batch.
TL;DR: The anatomy, histology and ultrastructure of immature ovarioles of the 1st-instar nymphs of Machilis helleri (Thysanura : Machilidae) are described and segmental arrangement of o varioles in Archaeognatha is discussed.
Abstract: The anatomy, histology and ultrastructure of immature ovarioles of the 1st-instar nymphs of Machilis helleri (Thysanura : Machilidae) are described. The nymphs have 7 pairs of segmentally arranged panoistic ovariole primordia in which the germarium and previtellarium can be distinguished. The germarium contains oogonia, young oocytes, and prefollicular cells. The previtellarium is filled with previtellogenic oocytes, prefollicular cells, and a pyramid-like group of somatic cells representing the primordium of the pedicel and oviduct. The ultrastructure of individual types of cells correlates to a great extent with the respective cells of ovarioles of adult machilids. Oogonia undergo mitosis in the germarium and transform into young oocytes. These grow and develop into previtellogenic oocytes characterized by changes in the nucleolus and by emission of ribonucleoproteinaceous bodies from the nucleus into cytoplasm. Segmental arrangement of ovarioles in Archaeognatha is discussed in view of contemporary hypotheses on the anagenesis of the reproductive system of Articulata.
TL;DR: The anatomy of the follicular (ovarian) sheath surrounding the embryos in the virginoparae of the vetch aphid, Megoura viciae Buckton, is described and the structure of the epidermal cells of the embryos indicates role in the uptake of materials.
Abstract: The anatomy of the follicular (ovarian) sheath surrounding the embryos in the virginoparae of the vetch aphid, Megoura viciae Buckton (Homoptera : Aphididae) is described. Enlarging oocytes released from the germaria are enveloped in a monolayer of cells derived from the prefollicular tissue, which is continuous with the sheat surrounding the germarium. Each embryo is compartmentalized. Initially, the sheath cells are cuboidal, but as division and elongation of the oocytes ensue, they become progressively stretched. Sheath cells surrounding large embryos show some variability in structure. In some areas, they are little more than a pair of membranes separated by a trace of cytoplasm. In other areas, they are thicker and have a structure that indicates a role in the uptake of materials. In these areas, the cells are often invaginated, with particulate and flocculent material present in the folds, and numerous organelles in the cytoplasm. Microvilli occur around some of the sheath cells and microtubule bundles are present in cells where the sheath is folded to form areas of contact between cells. A very thin acellular tunica propria is present to the exterior of the follicular sheath cells. Two acellular “membranes” present between the sheath cells and embryonic epidermal cells may have a role in the regulation of materials transfer. The structure of the epidermal cells of the embryos indicates role in the uptake of materials.
TL;DR: The fine structure of the basiconica sensilla situated on the posterior part of trochanters in Campodea sensillifera (Diplura : Campodeidea) reveals that they are probably olfactory and mechano-sensitive setae.
Abstract: The fine structure of the basiconica sensilla situated on the posterior part of trochanters in Campodea sensillifera (Diplura : Campodeidea) reveals that they are probably olfactory and mechano-sensitive setae. Each sensillum is composed of one sensory axis made of 3 dendrites ensheathed by 3 cells (thecogen, trichogen and tormogen); one outer segment ends by a tubular corper without connection with the cuticular layer. The setae are generally racket-shaped. The epicuticular layer of the expanded part is perforated by a lattice of numerous slits, which communicate with underlying canals. The ciliary structures and apex of the tormogen cell are eliminated just before ecdysis. The ciliary microtubules are present in the cavity of the new sensillum, but after ecdysis the microtubules persist only at the lower part of the peduncle. An ecdysial canal appears at the tip of the sensillum.
TL;DR: The close relationship between 2 separate endomembrane systems of different origins indicates a functional interdependence between the 2 partners, and suggests the division of the endoplasmic reticulum into domains with structural and functional diversity.
Abstract: In secondary spermatocytes of Notonecta glauca (Heteroptera : Hydrocorisae) associated membranes occur in a certain area of the cytoplasm near the nucleus. They consist of 2 separate endomembrane systems of different origins. One component comprises parts of extended endoplasmic cisternae, the other numerous vesicles of rather uniform size and shape derived from the Golgi apparatus and attached to the endoplasmic cisternae in a very regular array. Open connections or specialized contacts between the 2 systems do not exist. The close relationship, nevertheless, indicates a functional interdependence between the 2 partners, and suggests the division of the endoplasmic reticulum into domains with structural and functional diversity.
TL;DR: Frozen fractured cuticle reveals the presence of horizontal ducts or channels that run laterally within the cuticle of the alpine, weta Hemideina maori (Saussure) and the structure of weta cuticle is compared with that of the common house cricket and arthropods in general.
Abstract: Sclerotized cuticle segments from the thorax, dorsal abdomen, and ventral abdomen of the alpine, weta Hemideina maori (Saussure) (Orthoptera: Stenopelmatidae) were examined by light microscopy and by scanning and transmission electron microscopy. An epicuticle, exocuticle (outer and inner), mesocuticle, endocuticle, and deposition layer are present in transverse sections. The epicuticle is further composed of a cuticulin layer and inner epicuticle, the latter being finely laminated and containing narrow wax canals that terminate below the cuticle surface. Openings to dermal gland ducts are visible on the surface as are large setae and smaller sensory pegs. Frozen fractured cuticle reveals the presence of horizontal ducts or channels that run laterally within the cuticle. The structure of weta cuticle is compared with that of the common house cricket and arthropods in general.
TL;DR: Two differentiated sections (S1 and S2) of the salivary gland of Trichosia pubescens (Morgante) (Diptera : Sciaridae) have been examined by electron microscopy for fine structural alterations that occur in the cell cytoplasm during larval development.
Abstract: Two differentiated sections (S1 and S2) of the salivary gland of Trichosia pubescens (Morgante) (Diptera : Sciaridae) have been examined by electron microscopy for fine structural alterations that occur in the cell cytoplasm during larval development. Such changes have been correlated with the puffing patterns of the polytene chromsomes. During stage 1 (end of the 3rd instar to mid 4th instar), the puffing pattern and the ultrastructure of S1 and S2 cells are rather constant. Nevertheless, marked differences are noted when the puffs and the fine structure of the 2 sections are compared. In S1, secretory material is concentrated and eliminated as membrane-bound granules, while in S2, secretory granules are not detected and the elimination of secretion seems to occur continuously. At stage 2 (end of the 4th instar), the puffing pattern undergoes considerable alterations simultaneously with the appearance of many ultrastructural modifications. In S1, the morphological aspect of the secretory granules is altered, while in S2 a decline in the secretory activity is detected. At stage 3 (older 4th-instar larvae), most of DNA puffs are active, there being no striking differences in the puffing pattern between S1 and S2. This stage is marked by the onset of gland histolysis, with the appearance of an intense autophagic activity of lysosomes in S1 and S2. As histolysis progresses during stage 4 (prepupae and early pupae) the activity of the polytene chromosomes decreases; most of the cells present a large number of autophagic vacuoles and an increasing disorganization of the cytoplasm, leading to the final lysis of the gland.
TL;DR: The immunodetection of villin in both hind- and midgut points out that villin exists in ectodermal tissues as well as in endodermal or mesodermal ones, and may indicate that vill in is a conserved molecule in several taxa.
Abstract: The brush border of the larval midgut and hindgut in Calliphora vicina (Diptera : Calliphoridae) shows a positive staining with a rabbit antiserum directed against pig villin. This protein has been extensively studied in chicken and in several mammals; it is known to bind together the actin filaments of the microvillar cytoskeleton. The presence of a villin-like protein in insect microvilli has never been reported. The immunodetection of villin in both hind- and midgut points out that villin exists in ectodermal tissues as well as in endodermal or mesodermal ones. Moreover, the “insect villin” seems to present the polypeptidic sequence of 13 amino acids, which has been found in both mammalian and avian villin. That may indicate that villin is a conserved molecule in several taxa.