Concentric Lamellae Research Articles

Investigation on chlorosomal antenna geometries: tube, lamella and spiral-type self-aggregates

Molecular mechanics calculations and exciton theory have been used to study pigment organization in chlorosomes of green bacteria. Single and double rod, multiple concentric rod, lamella, and Archimedean spiral macrostructures of bacteriochlorophyll c molecules were created and their spectral properties evaluated. The effects of length, width, diameter, and curvature of the macrostructures as well as orientations of monomeric transition dipole moment vectors on the spectral properties of the aggregates were studied. Calculated absorption, linear dichroism, and polarization dependent fluorescence-excitation spectra of the studied long macrostructures were practically identical, but circular dichroism spectra turned out to be very sensitive to geometry and monomeric transition dipole moment orientations of the aggregates. The simulations for long multiple rod and spiral-type macrostructures, observed in recent high-resolution electron microscopy images (Oostergetel et al., FEBS Lett 581:5435-5439, 2007) gave shapes of circular dichroism spectra observed experimentally for chlorosomes. It was shown that the ratio of total circular dichroism intensity to integrated absorption of the Q(y) transition is a good measure of degree of tubular structures in the chlorosomes. Calculations suggest that the broad Q(y) line width of chlorosomes of sulfur bacteria could be due to (1) different orientations of the transition moment vectors in multi-walled rod structures or (2) a variety of Bchl-aggregate structures in the chlorosomes.

Macromol. Theory Simul. 2–3/2008

Cover: The picture on the cover shows a phase diagram for lamella‐forming ABA triblock copolymers confined in cylindrical pores of various diameters (D/L0) and of different surface preferences (α). Schematics of chains in concentric lamellae are given on the right side of the cover. Further details can be found in the article by Z. Wang, B. Li,* Q. Jin, D. Ding, and A.‐C. Shi* on page 86.

Imaging of intracellular spherical lamellar structures and tissue gross morphology by a focused ion beam/scanning electron microscope (FIB/SEM)

We report the use of a focused ion beam/scanning electron microscope (FIB/SEM) for simultaneous investigation of digestive gland epithelium gross morphology and ultrastructure of multilamellar intracellular structures. Digestive glands of a terrestrial isopod ( Porcellio scaber, Isopoda, Crustacea) were examined by FIB/SEM and by transmission electron microscopy (TEM). The results obtained by FIB/SEM and by TEM are comparable and complementary. The FIB/SEM shows the same ultrastructural complexity of multilamellar intracellular structures as indicated by TEM. The term lamellar bodies was used for the multillamellar structures in the digestive glands of P. scaber due to their structural similarity to the lamellar bodies found in vertebrate lungs. Lamellar bodies in digestive glands of different animals vary in their abundance, and number as well as the thickness of concentric lamellae per lamellar body. FIB/SEM revealed a connection between digestive gland gross morphological features and the structure of lamellar bodies. Serial slicing and imaging of cells enables easy identification of the contact between a lamellar body and a lipid droplet. There are frequent reports of multilamellar intracellular structures in different vertebrate as well as invertebrate cells, but laminated cellular structures are still poorly known. The FIB/SEM can significantly contribute to the structural knowledge and is always recommended when a link between gross morphology and ultrastrucutre is investigated, especially when cells or cellular inclusions have a dynamic nature due to normal, stressed or pathological conditions.

Self-assembly of diblock copolymers confined in cylindrical nanopores

Self-assembly of AB diblock copolymers confined in cylindrical nanopores is studied using a simulated annealing technique. The pore diameter and surface preference are systematically varied to examine their effects on the self-assembled morphologies and the chain conformations. For bulk lamella-forming and cylinder-forming diblock copolymers, novel structures such as helices and concentric (perforated) lamellae spontaneously form when the copolymers are confined in cylindrical pores. The observed equilibrium morphologies are compared with that obtained from experiments, theory, and other simulations. A simple model is proposed for symmetric diblock copolymers, which gives a reasonable description of the layer thickness for the concentric lamellae. It is found that chains near the pore surfaces are compressed relative to the bulk chains, which can be attributed to the existence of the surfaces. The dependence of the chain conformation on the degree of confinement and strength of the surface preference are reasonably explained. The energetics is discussed qualitatively and used to account for the appearance of the complex phase behavior observed for certain intermediate conditions.

SKELETAL MICROSTRUCTURE OF HELENS, LATERAL SPINES OF HYOLITHIDS

Abstract: In hyolithids the skeleton consists of four elements: a conch, an operculum and a pair of long, logarithmically curved ‘spines’ called helens. These last elements are rarely preserved, and have therefore remained poorly known and enigmatic. We have studied three‐dimensionally preserved helens of the species ‘Hyolithes’lanceolatus, from the Permian of New South Wales, Australia, and ‘Hyolithes’groenwalli, from the Cambrian of Bornholm, Denmark. Helens were massive calcareous elements. Their original microstructure, herein reported for the first time, consisted of concentric lamellae surrounding a narrow elongated core, which may have been rich in organic matter. This concentric pattern resulted from the successive accretion of shell material at the proximal, internal portion of helens. This growth model is in accordance with helen morphology and with the presence of a characteristic surface sculpture of overlapping lamellae.

Morphological and optical properties of the corneal lens and retinal structure in the posterior large stemma of the tiger beetle larva

The morphological and optical features of the corneal lens and retina have been examined in the posterior large stemma of the larva of the tiger beetle ( Cicindela chinensis). A cup-shaped retina was positioned 55 ± 6 μm beneath the posterior margin of the corneal lens, which was 479 ± 20 μm in diameter and 391 ± 18 μm in thickness ( n = 41). A light path through an isolated corneal lens showed that the object at infinite distance was focused on the distal margin of the retina. Geometrical optics gave a value of 334 ± 15 μm ( n = 55) for the posterior focal length of the corneal lens. The refractive index of the corneal lens was estimated to be around 1.8, if the lens was considered to be homogenous in structure. The internal structure of the lens, including concentric lamellae, was presumed to contribute to such a high refractive index, because this was higher than that of insect cuticle. The retinal structure and how images were blurred at different focus levels were also examined. Data obtained for optics of the corneal lens and retinal structures are discussed with reference to the distinct visual behavior of the larva.

Distribution and composition of esterified and unesterified cholesterol in extra-macular drusen

More details about the distribution of esterified and unesterified cholesterol (EC, UC), abundant druse components, would inform models of druse biogenesis and new technologies for ocular imaging. From donors with grossly normal maculas ( n = 10, 66–86 years), whose eyes were preserved in paraformaldehyde within 6 h of death, extra-macular drusen encased with retinal pigment epithelium (RPE) were isolated manually. Cryosections of pelleted drusen, stained with filipin for UC and EC, were used to investigate filipin staining patterns within single drusen ( n = 193) and to quantify fluorescence ( n = 146). From lipid extracts of other drusen/RPE and RPE samples, total cholesterol (TC) and UC were determined by enzymatic fluorimetry. Drusen contained cores, basally located regions that were intensely bright when stained for UC or deeply dark when stained for EC; many were surrounded by concentric lamellae. Within the same cores, the EC-poor regions were significantly smaller (13.0 μm) than UC-rich regions (17.1 μm). Drusen with highly fluorescent EC-rich shells lacked UC-rich shells. Small spots representing lakes were visible only in drusen stained for EC. Some drusen had small, refractive spherical inclusions lacking both UC and EC. Of drusen examined, 32% had a UC-rich core, 35% had an EC-poor core, 31% had an EC-rich shell, 25% had EC-rich lakes, and 4–5% had UC-, EC-poor inclusions. Shells and cores occurred in significantly non-overlapping druse populations. The percentage of TC that was esterified ranged from 32–66% for drusen/RPE and 5–21% for RPE. The disposition of cholesterol in cores may reflect the activity of invading cellular process. The greater size of UC-rich cores relative to EC-poor cores may reflect a declining gradient of enzymatic activity with increased radial distance from the putative invaders. The relative sizes of sub-domains defined by cholesterol composition are compared to sub-domains detected in drusen by in vivo imaging methods.

Quantifying the contributions of structure to annulus fibrosus mechanical function using a nonlinear, anisotropic, hyperelastic model

The annulus fibrosus of the intervertebral disc is comprised of concentric lamella of oriented collagen fibers embedded in a hydrated proteoglycan matrix with smaller amounts of minor collagens, elastin, and small proteoglycans. Its structure and composition enable the disc to withstand complex loads and result in inhomogeneous, anisotropic, and nonlinear mechanical behaviors. The specific contributions of the annulus fibrosus constituent structures to mechanical function remain unclear. Therefore, the objective of this study was to use a structurally motivated, anisotropic, nonlinear strain energy model of annulus fibrosus to determine the relative contributions of its structural components to tissue mechanical behavior. A nonlinear, orthotropic hyperelastic model was developed for the annulus fibrosus. Terms to describe fibers, matrix, and interactions between annulus fibrosus structures (shear and normal to the fiber directions) were explicitly included. The contributions of these structures were analyzed by including or removing terms and determining the effect on the fit to multidimensional experimental data. Correlation between experimental and model-predicted stress, a Bland-Altman analysis of bias and standard deviation of residuals, and the contribution of structural terms to overall tissue stress were calculated. Both shear and normal interaction terms were necessary to accurately model multidimensional behavior. Inclusion of shear interactions more accurately described annulus fibrosus nonlinearity. Fiber stretch and shear interactions dominated contributions to circumferential direction stress, while normal and shear interactions dominated axial stress. The results suggest that interactions between fibers and matrix, perhaps facilitated by crosslinks, elastin, or minor collagens, augment traditional (i.e., fiber-uncrimping) models of nonlinearity.

A HIGH-LATITUDE EPILITHOZOAN FAUNA ON QUARTZITE CLASTS AND THE PROBLEM OF COBBLE TRANSPORT ACROSS A COASTAL PLAIN: MIDDLE TURONIAN KASKAPAU FORMATION, BRITISH COLUMBIA, CANADA

Abstract The Middle Turonian Kaskapau Formation in the Rocky Mountain Foothills of northeastern British Columbia comprises up to 950 m of shallow marine sandstones cyclically interstratified with marine mudstones and minor lagoonal deposits. Transgressive surfaces are commonly mantled by thin pebble lags. A transgressive pebble lag exposed in Quality Creek near Tumbler Ridge town site includes rare, well-rounded quartzite cobbles and a quartzite boulder, which were deposited at a paleolatitude of about 67°N. Encrusting organisms are unevenly distributed over five of the largest clasts. Disciniscid brachiopods are abundant on one cobble but are otherwise rare. A conical-shelled lingulate brachiopod with concentric growth lamellae occurs sparsely, and a weakly ribbed lingulate brachiopod is represented by one shell. Serpulid worm tubes, encrusting bryozoans, and possible basal attachments of corals are also present. Attached foraminifera are abundant and distributed over several clasts. Generic diversity an...

Novel Transgenic Rabbit Model Sheds Light on the Puzzling Role of Matrix Metalloproteinase-12 in Atherosclerosis

Matrix metalloproteinases (MMPs), also termed matrixins, are known to affect atherosclerosis in many diverse ways.1–3 Apart from a role in the progression of atherosclerotic lesions, MMPs have also been involved in plaque destabilization and rupture and in the development of aneurysms. Despite intense research efforts during the last decade, it has been challenging to formulate a unifying model on the specific role of MMPs in atherosclerosis. In fact, mouse genetic studies have yielded controversial insights, highly dependent on genetic background, dietary regimen, and arterial site of analysis, whereas human genetic association studies do not prove causality of MMPs in atherosclerosis. Moreover, the lack of specific inhibitors precluded pharmacological dissection of the role of MMPs in vivo. There is thus a need for alternative strategies to decipher the MMP puzzle in atherosclerosis. In this issue of Circulation , Liang et al4 used a novel approach: They generated transgenic rabbits to study the role of MMP-12, also known as macrophage elastase, in atherosclerosis. Their results indicate that MMP-12 causes media destruction and pseudoaneurysm formation and, more surprisingly, accelerates plaque growth in an animal model that more closely resembles atherosclerosis in humans. Article p 1993 MMPs belong to one of the most ancient families of enzymes that arose in evolution soon after the first signs of life to regulate, in general, interactions of cells with the extracellular matrix (ECM). To cope with this formidable challenge, more than 65 structurally related MMPs developed in bacteria, plants, nematodes, fruit flies, sea urchins, and vertebrates. One of their key activities is breaking down ECM substrates in the basement membrane and interstitial matrix.1,2 As such, MMPs facilitate migration of macrophages and smooth muscle cells (SMCs) in atherosclerotic plaques by degrading ECM barriers, exposing novel ECM adhesion sites, and relieving the binding between basement membrane …

Histology and Pathology of the Human Intervertebral Disc

The intervertebral disc is a highly organized matrix laid down by relatively few cells in a specific manner. The central gelatinous nucleus pulposus is contained within the more collagenous anulus fibrosus laterally and the cartilage end plates inferiorly and superiorly. The anulus consists of concentric rings or lamellae, with fibers in the outer lamellae continuing into the longitudinal ligaments and vertebral bodies. This arrangement allows the discs to facilitate movement and flexibility within what would be an otherwise rigid spine. At birth, the human disc has some vascular supply within both the cartilage end plates and the anulus fibrosus, but these vessels soon recede, leaving the disc with little direct blood supply in the healthy adult. With increasing age, water is lost from the matrix, and the proteoglycan content also changes and diminishes. The disc-particularly the nucleus-becomes less gelatinous and more fibrous, and cracks and fissures eventually form. More blood vessels begin to grow into the disc from the outer areas of the anulus. There is an increase in cell proliferation and formation of cell clusters as well as an increase in cell death. The cartilage end plate undergoes thinning, altered cell density, formation of fissures, and sclerosis of the subchondral bone. These changes are similar to those seen in degenerative disc disease, causing discussion as to whether aging and degeneration are separate processes or the same process occurring over a different timescale. Additional disorders involving the intervertebral disc can demonstrate other changes in morphology. Discs from patients with spinal deformities such as scoliosis have ectopic calcification in the cartilage end plate and sometimes in the disc itself. Cells in these discs and cells from patients with spondylolisthesis have been found to have very long cell processes. Cells in herniated discs appear to have a higher degree of cellular senescence than cells in nonherniated discs and produce a greater abundance of matrix metalloproteinases. The role that abnormalities play in the etiopathogenesis of different disorders is not always clear. Disorders may be caused by a genetic predisposition or a tissue response to an insult or altered mechanical environment. Whatever the initial cause, a change in the morphology of the tissue is likely to alter the physiologic and mechanical functioning of the tissue.

HISTOLOGY AND PATHOLOGY OF THE HUMAN INTERVERTEBRAL DISC

The intervertebral disc is a highly organized matrix laid down by relatively few cells in a specific manner. The central gelatinous nucleus pulposus is contained within the more collagenous anulus fibrosus laterally and the cartilage end plates inferiorly and superiorly. The anulus consists of concentric rings or lamellae, with fibers in the outer lamellae continuing into the longitudinal ligaments and vertebral bodies. This arrangement allows the discs to facilitate movement and flexibility within what would be an otherwise rigid spine. At birth, the human disc has some vascular supply within both the cartilage end plates and the anulus fibrosus, but these vessels soon recede, leaving the disc with little direct blood supply in the healthy adult. With increasing age, water is lost from the matrix, and the proteoglycan content also changes and diminishes. The disc—particularly the nucleus—becomes less gelatinous and more fibrous, and cracks and fissures eventually form. More blood vessels begin to grow into the disc from the outer areas of the anulus. There is an increase in cell proliferation and formation of cell clusters as well as an increase in cell death. The cartilage end plate undergoes thinning, altered cell density, formation of fissures, and sclerosis of the subchondral bone. These changes are similar to those seen in degenerative disc disease, causing discussion as to whether aging and degeneration are separate processes or the same process occurring over a different timescale. Additional disorders involving the intervertebral disc can demonstrate other changes in morphology. Discs from patients with spinal deformities such as scoliosis have ectopic calcification in the cartilage end plate and sometimes in the disc itself. Cells in these discs and cells from patients with spondylolisthesis have been found to have very long cell processes. Cells in herniated discs appear to have a higher degree of cellular senescence than cells in nonherniated discs and produce a greater abundance of matrix metalloproteinases. The role that abnormalities play in the etiopathogenesis of different disorders is not always clear. Disorders may be caused by a genetic predisposition or a tissue response to an insult or altered mechanical environment. Whatever the initial cause, a change in the morphology of the tissue is likely to alter the physiologic and mechanical functioning of the tissue.

The structural basis of interlamellar cohesion in the intervertebral disc wall

The purpose of this study was to investigate the structural mechanisms that create cohesion between the concentric lamellae comprising the disc annulus. Sections, 50-60 microm thick, were obtained using a carefully chosen cutting plane that incorporated the fibrous component in alternating lamellae as in-plane and cross-sectioned arrays. These sections were then subjected to microtensile stretching both across (radial) and along (tangential) the in-plane fibre direction, in their fully hydrated state. Structural responses were studied by simultaneously viewing the sections using high-resolution Nomarski interference contrast light microscopy. Additional bulk samples of annulus were fixed while held in a constant, radially stretched state in order to investigate the potential for interlamellar separation to occur in a state more representative of the intact disc wall. The study has provided a detailed picture of the structural architecture creating disc wall cohesion, revealing a complex hierarchy of interconnecting relationships within the disc wall, not previously described. Importantly, because our experimental approach offers a high-resolution view of the response of the interlamellar junction to deformation in its fully hydrated condition, it is a potentially useful method for investigating subtle changes in junction cohesion resulting from both early degeneration and whole-disc trauma.

The lipid composition of autophagic vacuoles regulates expression of multilamellar bodies

Multilamellar bodies (MLBs) are responsible for surfactant secretion in type II alveolar cells but also accumulate in other cell types under pathological conditions, including cancer and lysosomal storage diseases such as Niemann-Pick C (NPC), a congenital disease where defective cholesterol transport leads to its accumulation in lysosomes. Mv1Lu type II alveolar cells transfected with Golgi beta1,6 N-acetylglucosaminyltransferase V (Mgat5), enhancing the polylactosamine content of complex-type N-glycans, exhibit stable expression of MLBs whose formation requires lysosomal proteolysis within dense autophagic vacuoles. MLBs of Mgat5-transfected Mv1Lu cells are rich in phospholipids and have low levels of cholesterol. In Mv1Lu cells treated with the NPC-mimicking drug U18666A, cholesterol-rich MLBs accumulate independently of both Mgat5 expression and lysosomal proteolysis. Inhibition of autophagy by blocking the PI 3-kinase pathway with 3-methyladenine prevents MLB formation and results in the accumulation of non-lamellar, acidic lysosomal vacuoles. Treatment with 3-methyladenine inhibited the accumulation of monodansylcadaverine, a phospholipid-specific marker for autophagic vacuoles, but did not block endocytic access to the lysosomal vacuoles. Induction of autophagy via serum starvation resulted in an increased size of cholesterol-rich MLBs. Although expression of MLBs in the Mv1Lu cell line can be induced by modulating lysosomal cholesterol or protein glycosylation, an autophagic contribution of phospholipids is critical for the formation of concentric membrane lamellae within late lysosomal organelles.

Ectothiorhodosinus mongolicum gen. nov., sp. nov., a New Purple Bacterium from a Soda Lake in Mongolia

A new purple sulfur bacterium (strain M9) was isolated from the steppe soda Lake Dzun Uldziin Nur (pH 9.4; mineralization, 3.3%) situated in southeastern Mongolia. Individual cells appear as vibrios 0.3-0.5 x 0.7-1 micron in size. The dividing cells often do not separate from each other, forming an almost closed ring. The internal photosynthetic membranes are represented by concentric lamellae lining the cell wall. Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The main carotenoid (> 96%) is spirilloxanthin. Two typical light-harvesting complexes (LH1 and LH2) are present in the membranes in a 1:1 ratio. The bacterium is an anaerobe and facultative photoorganoheterotroph. Photolithoautotrophic growth on sulfide is scarce. Thiosulfate is utilized as an electron donor only in the presence of organic matter. Globules of elemental sulfur are formed as an intermediary product of sulfide and thiosulfate oxidation and are deposited outside the cells. The end product of oxidation is sulfate. In the presence of sulfide and carbonates, acetate, lactate, malate, pyruvate, propionate, succinate, and fumarate are used as the additional sources of carbon in anoxygenic photosynthesis. Vitamin are not required. The bacterium is an alkaliphile the pH optimum is at 8.3-9.1, the pH range is 7.6-10.1. The optimum NaCl concentration in the medium is 1 to 7%; the range is 0.5 to 0.9%. The optimum carbonate content in the medium is 2%; the range is 1 to 10%. The best growth occurs at 30-35 degrees C. The DNA G + C content is 57.5 mol%. According to the results of analysis of the 16S rRNA gene sequences, the new isolate M9 belongs to the phylogenetic cluster containing representatives of the family Ectothiorhodospiraceae within the class "Gammaproteobacteria." In this class, the new isolate forms a new branch, which occupies an intermediate position between the representatives of the genera Ectothiorhodospira and Thiorhodospira. Based on the phenotypic and genetic characteristics, the new purple sulfurbacterium was assigned to a new species of a new genus of the family Ectothiorhodospiraceae, Ectothiorhodosinus mongolicum gen. nov., sp. nov.

Species of Calydiscoides Young, l969 (Monogenea: Diplectanidae Bychowsky, 1957: Lamellodiscinae Oliver, 1969) from nemipterid fishes off Peninsular Malaysia.

Four new species of Calydiscoides Young, 1969 are described from three species of nemipterids caught off Kemaman, Terengganu, on the eastern coast of Peninsular Malaysia: C. monogrammae n. sp. from Scolopsis monogramma; C. conus n. sp. from S. magaritifer; C. scolopsidis n. sp. from S. margaritifer and S. monogramma; and C. kemamanensis n. sp. from Pentapodus setosus. The present investigation reveals that the squamodiscs (lamellodiscs) are composed of 10-12 short, complete, interlocking and concentric tubular lamellae. The innermost lamella is attached to a pair of adductor muscles.

Testicular histology of cryptorchid black-tailed deer (Odocoileus hemionus sitkensis) of Kodiak island, Alaska

Histological structure of intraabdominally located testes and epididymis of cryptorchid black-tailed deer (Odocoileus hemionus sitkensis) of Kodiak island, Alaska was compared with the gonads of intact deer sampled in the same region. The deer were harvested during the rut and their age, antler and gonadal status were recorded. The seminiferous tubules of cryptorchid bucks were malformed, lined only with Sertoli cells and were devoid of any spermatogenetic activity. A great number of blood vessels including arteries were detected within the remnants of tubules. In addition, inclusions comprised of concentric lamellae, containing most probably calcium salts, were observed in the lumen of degenerated tubules. Conversely, we encountered large areas of cells resembling Leydig cells, exhibiting an abundant cytoplasm. The production of testosterone in these cells would explain why an almost normal antler shape and a quasi-normal antler cycle were often observed in many bilateral cryptorchids. Epididymides accompanying the ectopic testes were devoid of any spermatozoa but otherwise were of almost normal size; only in the bilateral cryptorchid the epithelium was partly malformed. It was concluded, that hypoplastic or cryptorchid testes cause male infertility but the production of testosterone in the less affected Leydig cells is sufficient to initiate and control the antler cycle.

On the Lamellar Structure of the Tracheid Cell Wall

Abstract: It is clear that cross sections of wood cells show a lamellar structure. This paper investigates the orientation of this lamellar structure of spruce (Picea abies) tracheids using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Cross sections of spruce wood were produced through fracturing in longitudinal bending and tensile testing. When investigated with SEM, the fracture surfaces show a structure of mostly larger radial lamellae, in the order of 30 ‐ 100 nm, i.e., agglomerations of a few cellulose aggregates. Thin transverse sections of the fracture zones investigated with atomic force microscopy show concentric lamellae with a width in the order of a single cellulose aggregate, i.e., 15 ‐ 25 nm. No structural connection to the splinters in the radial direction can be seen. It is suggested that the radial lamellar structure is a consequence of the energy released during fracturing of the wood samples and that the undistorted wood has a concentric lamellar structure on a smaller structural level.

Bacteria in ovarioles of females from maleless families of ladybird beetles Adalia bipunctata L. (Coleoptera: Coccinellidae) naturally infected with Rickettsia, Wolbachia, and Spiroplasma.

Ovarioles were found to be infected with Spiroplasma, Wolbachia, and Rickettsia in Adalia bipunctata females with maleless progeny in different natural populations. Ooplasm was infected with few Wolbachia bacteria. In ooplasm infected by Rickettsia, bacteria were present in small foci. Spiroplasmas were found encapsulated into ooplasm from the wider intercellular spaces between epithelial and oocyte cells. The cytoplasm of follicular epithelia infected with Rickettsia was heavily destroyed, but the nucleus was intact and free from bacteria. The essential feature of follicular epithelium cells from Spiroplasma and Wolbachia infected A. bipunctata females was inclusions of three types: crystalline, filaments, and concentric myelin-like lamellae. Observations of smears prepared from ovaries of A. bipunctata from natural populations revealed a low concentration of bacteria within a microscopy field (less 10 bacteria) in more than 90% of specimens, and only a few ovaries were heavily infected. Two different ways of bacterial invasion of the oocyte are suggested: Spiroplasma-like, through the intercellular spaces in the epithelium and Rickettsia-like, through the cytoplasm of follicular epithelium cells. Bacteria were not found in germarium zones and we suggest that each follicle is infected from haemolymph.

Functional anatomy of the spermatheca and its duct in the seed bug Lygaeus simulans (Heteroptera: Lygaeidae)

Female genitalia of lygaeid bugs are characterized by a tube-shaped ductus receptaculi (spermathecal duct) connecting the bursa copulatrix with the highly coiled receptaculum seminis (spermatheca). In this study the morphology and functional anatomy of these structures in Lygaeus simulans were examined by light-, fluorescence- and electron microscopy. In addition, copulating animals were freeze fixed and their interconnected genital structures observed using light microscopy. The ductus receptaculi is separated from the receptaculum seminis by a complicated valve. The valve is nearly surrounded by the spermathecal muscle, which controls its opening. The ductus receptaculi leads into the proximal convoluted tube of the receptaculum seminis. Both the ductus receptaculi and the convoluted tube are composed of a single layer of epithelial cells lined by a thick electron dense apical cuticle. The distal part of the receptaculum seminis is a brownish, irregularly coiled, blind ending canal made of small epithelial cells covered with cuticle. Big glands are present in the epidermal layer. The cuticle of this distal part is much thinner and features concentric lamellae. The lumen of the receptaculum seminis cannot be expanded. For transfering sperm into the receptaculum the male aedeagus is equipped with a long, tube-like, sclerotized appendix (processus gonopori), which enlarges the ductus receptaculi considerably during copulation. For successful insemination the tip of the processus gonopori has to pass the valve. The convoluted tube, the valve and the surrounding spermathecal muscle may enable females to control insemination and egg fertilization.