Showing papers on "Ultrastructure published in 2014"
TL;DR: It is shown that the GV stage appears more suitable for vitrification than the MII stage, as indicated by the good ultrastructural preservation of important structures that are present only in immature oocytes, like the nucleus and migrating CGs.
Abstract: In vitro maturation of vitrified immature germinal vesicle (GV) oocytes is a promising fertility preservation option. We analyzed the ultrastructure of human GV oocytes after Cryotop vitrification (GVv) and compared it with fresh GV (GVc), fresh mature metaphase II (MIIc) and Cryotop-vitrified mature (MIIv) oocytes. By phase contrast microscopy and light microscopy, the oolemmal and cytoplasmic organization of fresh and vitrified oocytes did not show significant changes. GVv oocytes showed significant ultrastructural alterations of the microvilli in 40% of the samples; small vacuoles and occasional large/isolated vacuoles were abnormally present in the ooplasm periphery of 50% of samples. The ultrastructure of nuclei and mitochondria-vesicle (MV) complexes, as well as the distribution and characteristics of cortical granules (CGs), were comparable with those of GVc oocytes. MIIv oocytes showed an abnormal ultrastructure of microvilli in 30% of the samples and isolated large vacuoles in 70% of the samples. MV complexes were normal, but mitochondria-smooth endoplasmic reticulum aggregates appeared to be of reduced size. CGs were normally located under the oolemma but presented abnormalities in distribution and matrix electron density. In conclusion, Cryotop vitrification preserved main oocyte characteristics in the GV and MII stages, even if peculiar ultrastructural alterations appeared in both stages. This study also showed that the GV stage appears more suitable for vitrification than the MII stage, as indicated by the good ultrastructural preservation of important structures that are present only in immature oocytes, like the nucleus and migrating CGs.
46 citations
TL;DR: In H. stigonocarpa, colleter arrangement is compatible with the hypothesis that they protect shoot apex, and in this species, protection is reinforced by the sheath formed by the stipule pairs.
Abstract: The genus Hymenaea is characterized by a great diversity of secretory structures, but there are no reports of colleters yet. The objectives of this study are to report the occurrence and describe the origin and structure of colleters in Hymenaea stigonocarpa Mart. ex Hayne. Shoot apex samples were collected, fixed, and processed for light microscopy, scanning electron microscopy, and transmission electron microscopy as per usual methods. Colleters occur predominantly on the stipule’s adaxial side. These structures are found at the base on a narrow strip, corresponding to the median vein up to half the length of the stipule. When present on the abaxial side, they are concentrated at the base and restricted to the margins. Colleters develop from the protoderm; they are elongate and club-shaped. Their body has no stratification; their surface cells differ from the inner cells only in position and presence of cuticle. Colleter cells have thin walls, dense cytoplasm, large nuclei, many mitochondria, rough endoplasmic reticulum, and abundant dictyosomes. Histochemical tests with Ruthenium red showed pectic compounds in the cytosol. In H. stigonocarpa, colleter arrangement is compatible with the hypothesis that they protect shoot apex. In this species, protection is reinforced by the sheath formed by the stipule pairs.
42 citations
TL;DR: Marked ultrastructural abnormalities observed in hepatocyte mitochondria, especially their polymorphism in the form of MMC and loss of mitochondrial cristae, accompanied by foamy cytoplasm, clearly indicate a major role of these organelles in the morphogenesis of pediatric NASH.
Abstract: AIM: To investigate the ultrastructure of abnormal hepatocyte mitochondria, including their cellular and hepatic zonal distribution, in bioptates in pediatric non-alcoholic steatohepatitis (NASH).
METHODS: Ultrastructural investigations were conducted on biopsy liver specimens obtained from 10 children (6 boys and 4 girls) aged 2-14 years with previously clinicopathologically diagnosed NASH. The disease was diagnosed if liver biopsy revealed steatosis, inflammation, ballooned hepatocytes, Mallory hyaline, or focal necrosis, varying degrees of fibrosis in the absence of clinical, serological, or histological findings of infectious liver diseases, autoimmune hepatitis, metabolic liver diseases, or celiac disease. For ultrastructural analysis, fresh small liver blocks (1 mm3 volume) were fixed in a solution containing 2% paraformaldehyde and 2.5% glutaraldehyde in 0.1 mol/L cacodylate buffer. The specimens were postfixed in osmium tetroxide, subsequently dehydrated through a graded series of ethanols and propylene oxide, and embedded in Epon 812. The material was sectioned on a Reichert ultramicrotome to obtain semithin sections, which were stained with methylene blue in sodium borate. Ultrathin sections were contrasted with uranyl acetate and lead citrate, and examined using an Opton EM 900 transmission electron microscope.
RESULTS: Ultrastructural analysis of bioptates obtained from children with non-alcoholic steatohepatitis revealed characteristic repetitive mitochondrial abnormalities within hepatocytes; mainly mitochondrial polymorphisms such as megamitochondria, loss of mitochondrial cristae, and the presence of linear crystalline inclusions within the mitochondrial matrix of an increased electron density. The crystalline inclusions were particularly evident within megamitochondria (MMC), which seemed to be distributed randomly both within the hepatic parenchymal cell and the zones of hepatic lobule, without special variations in abundance. The inclusions appeared as bundles viewed longitudinally, or as an evenly spaced matrix in cross section, and frequently caused mitochondrial deformation. The average diameter of these linear structures was 10 nm and the average space between them 20 nm. Sometimes enlarged intramitochondrial granules were seen in their vicinity. Foamy cytoplasm of hepatocytes was found, resulting from the proliferation of smooth endoplasmic reticulum and glycogen accumulation. The perivascular space of Disse was frequently dilated, and contained transitional hepatic stellate cells, as well as mature and/or newly forming collagen fiber bundles.
CONCLUSION: Marked ultrastructural abnormalities observed in hepatocyte mitochondria, especially their polymorphism in the form of MMC and loss of mitochondrial cristae, accompanied by foamy cytoplasm, clearly indicate a major role of these organelles in the morphogenesis of pediatric NASH. Our findings seem to prove the high effectiveness of electron microscopy in the diagnosis of the disease.
33 citations
TL;DR: The localization of IMPDH2 inside the nucleus of human cells as well as the ultrastructure of R&R inclusions are described, which show that the nuclear pool has an ability to form Rod structures after inhibition by ribavirin.
Abstract: Inosine-5'-monophosphate dehydrogenase catalyzes the critical step in the de novo synthesis of guanosine nucleotides: the oxidation of inosine monophosphate to xanthosine monophosphate. This reaction can be inhibited by specific inhibitors, such as ribavirin or mycophenolic acid, which are widely used in clinical treatment when required to inhibit the proliferation of viruses or cells. However, it was recently found that such an inhibition affects the cells, leading to a redistribution of IMPDH2 and the appearance of IMPDH2 inclusions in the cytoplasm. According to their shape, these inclusions have been termed "Rods and Rings" (R&R). In this work, we focused on the subcellular localization of IMPDH2 protein and the ultrastructure of R&R inclusions. Using microscopy and western blot analysis, we show the presence of nuclear IMPDH2 in human cells. We also show that the nuclear pool has an ability to form Rod structures after inhibition by ribavirin. Concerning the ultrastructure, we observed that R&R inclusions in cellulo correspond to the accumulation of fibrous material that is not surrounded by a biological membrane. The individual fibers are composed of regularly repeating subunits with a length of approximately 11 nm. Together, our findings describe the localization of IMPDH2 inside the nucleus of human cells as well as the ultrastructure of R&R inclusions.
32 citations
TL;DR: The stromal compartment maintained morphological and ultrastructural features similar to fresh tissue, while the oocyte cytoplasm was slightly damaged, although these data are encouraging, further studies are necessary and essential to optimize vitrification procedure.
Abstract: The aim of this study was to develop a vitrification procedure for human ovarian tissue cryopreservation in order to better preserve the ovarian tissue. Large size samples of ovarian tissue retrieved from 15 female-to-male transgender subjects (18–38 years) were vitrified using two solutions (containing propylene glycol, ethylene glycol, and sucrose at different concentrations) in an open system. Light microscopy, transmission electron microscopy, and TUNEL assay were applied to evaluate the efficiency of the vitrification protocol. After vitrification/warming, light microscopy showed oocyte nucleus with slightly thickened chromatin and irregular shape, while granulosa and stromal cells appeared well preserved. Transmission electron microscopy showed oocytes with slightly irregular nuclear shape and finely dispersed chromatin. Clear vacuoles and alterations in cellular organelles were seen in the oocyte cytoplasm. Stromal cells had a moderately dispersed chromatin and homogeneous cytoplasm with slight vacuolization. TUNEL assay revealed the lack of apoptosis induction by vitrification in all ovarian cell types. In conclusion after vitrification/warming the stromal compartment maintained morphological and ultrastructural features similar to fresh tissue, while the oocyte cytoplasm was slightly damaged. Although these data are encouraging, further studies are necessary and essential to optimize vitrification procedure.
31 citations
TL;DR: It is revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets.
Abstract: During the last decade several new orders were established in the class Chytridiomycetes on the basis of zoospore ultrastructure and molecular phylogeny. Here we present the ultrastructure and molecular phylogeny of strain x-51 CALU – a parasite of the alga Tribonema gayanum, originally described as Rhizophydium sp. based on light microscopy. Detailed investigation revealed that the zoospore ultrastructure of this strain has unique characters not found in any order of Chytridiomycetes: posterior ribosomal core unbounded by the endoplasmic reticulum and detached from the nucleus or microbody-lipid complex, and kinetosome composed of microtubular doublets. An isolated phylogenetic position of x-51 is further confirmed by the analysis of 18S and 28S rRNA sequences, and motivates the description of a new genus and species Gromochytrium mamkaevae. The sister position of G. mamkaevae branch relative to Mesochytrium and a cluster of environmental sequences, as well as the ultrastructural differences between Gromochytrium and Mesochytrium zoospores prompted us to establish two new orders: Gromochytriales and Mesochytriales.
31 citations
TL;DR: It is concluded that tissue preparation procedures may be optimised to facilitate the observation of the micro- and nanostructure of cuticular layers and components with different degrees of polarity and hydrophobicity.
Abstract: The leaf cuticular ultrastructure of some plant species has been examined by transmission electron microscopy (TEM) in only few studies. Attending to the different cuticle layers and inner structure, plant cuticles have been grouped into six general morphological types. With the aim of critically examining the effect of cuticle isolation and preparation for TEM analysis on cuticular ultrastructure, adaxial leaf cuticles of blue-gum eucalypt, grey poplar, and European pear were assessed, following a membrane science approach. The embedding and staining protocols affected the ultrastructure of the cuticles analysed. The solubility parameter, surface tension, and contact angles with water of pure Spurr's and LR-White resins were within a similar range. Differences were however estimated for resin : solvent mixtures, since Spurr’s resin is combined with acetone and LR-White resin is mixed with ethanol. Given the composite hydrophilic and lipophilic nature of plant cuticles, the particular TEM tissue embedding and staining procedures employed may affect sample ultrastructure and the interpretation of the results in physicochemical and biological terms. It is concluded that tissue preparation procedures may be optimised to facilitate the observation of the micro- and nanostructure of cuticular layers and components with different degrees of polarity and hydrophobicity.
29 citations
TL;DR: A protocol for HPF is described that is useful to monitor ultrastructural changes associated with functional changes at synapses in the brain but can be applied to many other tissues as well.
Abstract: Electron microscopy (EM) allows for the simultaneous visualization of all tissue components at high resolution However, the extent to which conventional aldehyde fixation and ethanol dehydration of the tissue alter the fine structure of cells and organelles, thereby preventing detection of subtle structural changes induced by an experiment, has remained an issue Attempts have been made to rapidly freeze tissue to preserve native ultrastructure Shock-freezing of living tissue under high pressure (high-pressure freezing, HPF) followed by cryosubstitution of the tissue water avoids aldehyde fixation and dehydration in ethanol; the tissue water is immobilized in ∼50 ms, and a close-to-native fine structure of cells, organelles and molecules is preserved Here we describe a protocol for HPF that is useful to monitor ultrastructural changes associated with functional changes at synapses in the brain but can be applied to many other tissues as well The procedure requires a high-pressure freezer and takes a minimum of 7 d but can be paused at several points
27 citations
TL;DR: The dominance of sER suggests its involvement in STL biosynthesis and cell wall protuberances enlarge the surface of the plasmamembrane of secretory cells and may be involved in the secretion processes of STL into the subcuticular space.
Abstract: Previous studies have shown that capitate glandular trichomes (CGT) of the common sunflower, Helianthus annuus, produce sesquiterpene lactones (STL) and flavonoids, which are sequestered and accumulated between the apical cuticle and the wall of the tip cells. To explore the cellular structures required and putatively involved in the STL biosynthesis and secretion, the present study was focused on the development of CGT and the comparison of the ultrastructure of its different cell types. Gradual maturation of flowers in the capitulum of the sunflower provided the possibility to study the simultaneous differentiation from the primordial to the secretory stage of CGT located by light microscopy (bright field, differential interference contrast and fluorescence) as well as transmission electron microscopy. It was shown that the CGT of sunflower anthers had a biseriate structure with up to 14 cell pairs. In mature trichomes, the apical cells called secretory cells were covered entirely by a large cuticle globe, which enclosed the resinous terpenoids and was specialised in thickness and structure. The secretory cells lacked chloroplasts and contained mainly smooth endoplasmic reticulum (sER). Conspicuous cell wall protuberances and an accumulation of mitochondria nearby occurred in the horizontally oriented cell walls. The cytological differences between stalk cells and secretory cells indicate a different function. The dominance of sER suggests its involvement in STL biosynthesis and cell wall protuberances enlarge the surface of the plasmamembrane of secretory cells and may be involved in the secretion processes of STL into the subcuticular space.
27 citations
TL;DR: It is proposed that mucilage is produced by dictyosomes present in the palisade-like epidermal cells of Bulbophyllum and Oncidiinae, which become chemically modified and form a protein-rich, mucilaginous secretion that accumulates in blisters formed from the distended cuticle.
24 citations
TL;DR: A new species of microsporidium isolated from gregarines Polyrhabdina sp.
Abstract: The present paper reports results of a transmission electron microscopy study of a new metchikovellid microsporidium. It was isolated from gregarines Polyrhabdina sp. inhabiting guts of polychaetes Pygospio elegans sampled at the White Sea silt littoral zone. Free sporogony (FS) occurred in the life cycle of the microsporidium alongside sac-bound sporogony (BS). Free spores resided in a parasitophorous vacuole and were of typical metchnikovellidean structure, uninucleate and oblong. They measured on sections 2·0-3·2×1·3-1·9 μm. The life cycle included pre-sporogonial stages represented by dikaryotic cells and 4-nucleate cells with coupled nuclei. A multinucleate sporogonial plasmodium of FS split in numerous (>10) sporoblasts. In BS segregation of sporoblasts occurred within thick-walled cysts by internal budding. Spore sacs of this microsporidium, measuring on average 11·6×4·7 μm, were limited by a thick electron-dense wall, externally ornamented with spirally wound cords of dense material. These oval spore sacs contained eight barrel-shaped spores, comparable in size and ultrastructure to FS spores. Ultrastructure of both types of spores and intracellular development of the new microsporidium and Metchnikovella spp. were similar, suggesting they belong to the same genus. In this paper we describe a new species Metchnikovella spiralis and discuss morphology of metchnikovellids in the context of putative evolutionary history of Microsporidia.
TL;DR: The results demonstrate that cadmium-induced plant cell death is a slow process featuring elements of vacuolar cell death and terminating with necrosis, and is accompanied by necrotic features including loss of plasmalemma integrity, shrinkage of the protoplast and unprocessed cellular components.
Abstract: Cadmium is a potent inducer of programmed cell death (PCD) in plants but the morphological changes in cells exposed to cadmium are poorly characterized. Using light and transmission electron microscopy (TEM) we have investigated the changes in ultrastructure of tobacco BY-2 cells treated with 50 µM CdSO4. The cadmium-induced alterations in cell morphology occurred gradually over a period of 3-4 days and the first stages of the response resembled vacuolar type of cell death. The initial formation of numerous small cytoplasmic vacuoles and dilation of endoplasmic reticulum was followed first by fusion of smaller vacuoles with each other and with big vacuoles, and then by the appearance of autophagic vacuoles containing autophagic bodies. The final stages of cell death were accompanied by necrotic features including loss of plasmalemma integrity, shrinkage of the protoplast and unprocessed cellular components. In addition, we observed a gradual degradation of nuclear material. Our results demonstrate that cadmium-induced plant cell death is a slow process featuring elements of vacuolar cell death and terminating with necrosis.
TL;DR: This method provides an efficient, easy and reproducible process to perform qualitative and quantitative TEM analysis from limited biological samples including cells in suspension, mainly hematopoietic stem cells and mitochondria.
TL;DR: Hydroxyapatite nanoparticles (nano-HAPs) were prepared by homogeneous precipitation, and size distribution and morphology of these nanoparticles were determined by laser particle analysis and transmission electron microscopy, respectively.
Abstract: Hydroxyapatite nanoparticles (nano-HAPs) were prepared by homogeneous precipitation, and size distribution and morphology of these nanoparticles were determined by laser particle analysis and transmission electron microscopy, respectively. Nano-HAPs were uniformly distributed, with rod-like shapes sizes ranging from 44.6 to 86.8 nm. Attached overnight, suspended, and proliferating Bel-7402 cells were repeatedly incubated with nano-HAPs. Inverted microscopy, transmission electron microscopy, and fluorescence microscopy were used to observe the cell adhesion and growth, the culture medium containing nano-HAPs, the cell ultrastructure, and intracellular Ca2
TL;DR: The ultrastructure of the autophagic structures in their midgut epithelium cells was studied by light microscopy, transmission electron microscope (TEM) and immunofluorescence microscopy (IFM) during this non-feeding period.
01 Jan 2014
TL;DR: This chapter reviews the key ultrastructural features of T. gondii life cycle forms using an extensive collection of micrographs provided by the authors.
Abstract: Electron microscopy has been an important tool for understanding the biology and ultrastructure of Toxoplasma gondii. As an obligate intracellular parasite, T. gondii has evolved specialized organelles for invasion and successful intracellular parasitism. Early electron microscopy studies identified the unique ultrastructural features of the secretory organelles of the various invasive forms of T. gondii. These studies also illuminated the features of the parasitophorous vacuole and intracellular development of T. gondii, as well as the development of the parasite during the sexual cycle and during formation of the latent bradyzoite forms. This chapter reviews the key ultrastructural features of T. gondii life cycle forms using an extensive collection of micrographs provided by the authors.
TL;DR: New light is shed on the effects of copper on C. elegans cuticle as well as some biological functions and some of the biological functions of nematodes were affected.
Abstract: Copper is an essential metal, but its toxic effects are pronounced when organisms are exposed to it in excessive amounts. However, information about the effects of chronic copper exposure on the cuticle ultrastructure of organisms is insufficient. Studies of the model organism, Caenorhabditis elegans, could further our understanding of the effect of chronic excessive copper exposure on human health. In this study, the cuticle surface ultrastructure of C. elegans was observed using scanning electron microscopy after excessive copper exposure. In addition to this, some biological functions, such as chemotaxis, reproduction, and development, were also analyzed. After chronic excessive copper exposure, the worms' body surface from vulva to tail was extensively wrinkled and folded along with the annulus. The worm's vulva size was significantly decreased, and the middle ridge of the alae was disrupted. Furthermore, some of the biological functions of nematodes were also affected: the chemotaxis index was partially changed, bags-of-worms were induced, development was delayed, and egg-laying number was decreased by copper treatment. The results of the present study shed new light on the effects of copper on C. elegans cuticle as well as some biological functions.
TL;DR: The reproductive system and the spermatozoon of Megadasys sterreri from Lanzarote were studied at structural and ultrastructural levels and a close relationship between the two taxa appears to be very likely; consequently, it is proposed to removeMegadasys from the family Cephalodasyidae and affiliate it to the family Planodasyids.
Abstract: The reproductive system and the spermatozoon of Megadasys sterreri from Lanzarote (Canary Islands, Spain) were studied at structural and ultrastructural levels. The species is a simultaneous hermaphrodite with cross-fertilization and shows paired gonads, the male anterior and the female posterior, and both gametes mature in a caudo-cephalic direction. Sperm ducts converge on the midline and open into a ventral common pore. Two sexual accessory organs are present in the caudal trunk. A pipe-like frontal organ lies between the ovaries and the caudal organ, and is composed of a long, thin region connected to a large zone containing mature and degenerating spermatozoa. The cigar-like caudal organ is elongate, bulky and is made of an anterior glandulo-muscular region and a posterior muscular one. Spermatozoa are long, filiform cells formed by an acrosome, a nucleus-mitochondrial complex, and a flagellum. The long acrosome is composed of an apical twisted region and a basal straight region. The nucleo-mitochondrial complex is formed by a spring-shaped nucleus surrounding basally the mitochondrion and apically a granular material. The flagellum has a 9x2+2 axoneme, characterized by a dense and prominent central sheath surrounding the central tubules. Megadasys sterreri (Cephalodasyidae) shows the same reproductive layout as Crasiella (Planodasyidae): paired gonads, caudo-cephalic maturation of gametes, sperm ducts converging into a common ventral pore, and two sexual accessory organs. Also the spermatozoa ultrastructure shows two similarities in the two genera: a peculiar prominent central sheath in the axoneme and a similar structure of the basal region of the acrosome. Considering the likely polyphyletic nature of the family Cephalodasyidae, and the sister-taxon relationship of Megadasys and Crasiella that emerged from a recent molecular phylogenetic study, a close relationship between the two taxa appears to be very likely; consequently, we propose to remove Megadasys from the family Cephalodasyidae and affiliate it to the family Planodasyidae.
TL;DR: Root cell ultrastructure and organelles changed significantly under Cu stress, in particular, cell walls, mitochondria, and xylem parenchyma were affected.
Abstract: A hydroponic culture experiment was conducted to study the effect of copper toxicity on root morphology, ultrastructure, and copper accumulation in Moso bamboo (Phyllostachys pubescens) Root ultrastructure of Moso bamboo was studied by transmission electron microscopy and scanning electron microscopy Application of 200 μM Cu resulted in an accumulation of 810 mg kg(-1) dry weight and 91 mg kg(-1) dry weight Cu in roots and shoots, respectively The majority of the plants did not survive the application of 400 μM Cu Biomass production declined consistently with application of each additional increment of Cu Root growth was more severely inhibited than shoot growth Cu adversely affected the root morphology of the plants, however, root surface area and number of root tips increased slightly at low levels of Cu Root cell ultrastructure and organelles changed significantly under Cu stress, in particular, cell walls, mitochondria, and xylem parenchyma were affected
TL;DR: It is suggested that the anterior esophageal region is an independent secretory organ that interacts with incoming blood via the tips of corrugation and binds strongly in a characteristic pattern to the anteriorEsophagus lining indicating that the secretions are highly immunogenic.
Abstract: Background: The esophagus of blood-feeding schistosomes has been largely neglected although its posterior portion was designated as a gland decades ago. However, we recently showed it plays a pivotal role in blood processing. It is clearly demarcated into anterior and posterior compartments, both surrounded by a mass of cell bodies. Feeding movies revealed that erythrocytes accumulate in the anterior compartment before entering the posterior, indicating that a distinct process is executed there. We therefore investigated ultrastructural aspects and possible functions of the anterior region. Methods: The heads of adult Schistosoma japonicum were detached and prepared for both transmission and scanning electron microscopy to define the detailed ultrastructure of the anterior esophagus. Cryosections of heads were also prepared for immunocytochemistry and confocal microscopy to define the pattern of intrinsic host antibody binding in the anterior esophageal lining. Results: The anterior syncytial lining of the esophagus is highly extended by long, thin corrugations of cytoplasm projecting towards the lumen. Strikingly in the male worm, the tips of the corrugations are further expanded by numerous threads of cytoplasm, producing a spaghetti-like appearance in the central lumen. Flattened, pitted cytoplasmic plates are interspersed in the tangled mass of threads. Abundant, morphologically distinct light vesicles of varied size and contents are manufactured in the cell bodies, from where they traffic through cytoplasmic connections to the corrugations and out to the tips. Clusters of vesicles accumulate in expanded tips in males, together with occasional mitochondria whilst females have more mitochondria but fewer vesicles. The membranous contents of light vesicles are secreted mainly from the tips, but also from the sides of the corrugations. They coat the surfaces and then form organised self-adherent membrane figures when shed into the lumen. Host antibody binds strongly in a characteristic pattern to the anterior esophageal lining indicating that the secretions are highly immunogenic. Conclusions: We suggest that the anterior esophageal region is an independent secretory organ. The contents of light vesicles are released into the esophageal lumen via the tips of corrugation to interact with incoming blood. Our immediate task is to establish their composition and role in blood processing.
TL;DR: The distinct morphology of LB organelles actively formed within macrophages in response to infections and cell clearance is revisited, taking into account new insights provided by ultrastructural studies.
Abstract: Macrophages are widely distributed immune system cells with essential functions in tissue homeostasis, apoptotic cell clearance, and first defense in infections. A distinguishing feature of activated macrophages participating in different situations such as inflammatory and metabolic diseases is the presence of increased numbers of lipid-rich organelles, termed lipid bodies (LBs) or lipid droplets, in their cytoplasm. LBs are considered structural markers of activated macrophages and are involved in different functions such as lipid metabolism, intracellular trafficking, and synthesis of inflammatory mediators. In this review, we revisit the distinct morphology of LB organelles actively formed within macrophages in response to infections and cell clearance, taking into account new insights provided by ultrastructural studies. We also discuss the LB interactions within macrophages, revealed by transmission electron microscopy, with a focus on the remarkable LB–phagosome association and discuss potential links between structural aspects and function.
TL;DR: The aim of the study is to investigate and visualize the ultrastructure of cataract morphology and repair, after in vivo exposure to double threshold dose UVR‐B in the C57BL/6 mouse lens.
Abstract: PurposeThe aim of the study is to investigate and visualize the ultrastructure of cataract morphology and repair, after in vivo exposure to double threshold dose UVR-B in the C57BL/6 mouse lens.MethodsTwenty-six-week-old C57BL/6 mice received in vivo double threshold dose (6.4 kJ/m2) UVR-B for 15 min. The radiation output of the UVR-source had λMAX at 302.6 nm. After a latency period of 1, 2, 4 and 8 days following UVR-B exposure, the induced cataract was visualized with electron microscopy techniques. Induced, cataract was quantified as forward lens light scattering. Damage to the lens epithelium and the anterior cortex was investigated with light microscopy in toluidine blue-stained semi-thin sections, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and dark field illumination photography.ResultsUVR-B-exposed lenses developed anterior subcapsular and/or cortical and nuclear cataract after 1 day. Lens light scattering peaked 2 days after exposure. Lens epithelial cell damage was seen in TEM as apoptotic cells, apoptotic bodies, nuclear chromatin condensation, and swollen and disrupted anterior cortex fibres throughout the sections of the whole anterior lens surface. These morphologic changes were also visualized with SEM. Within 8 days, anterior subcapsular cataract was repaired towards the anterior sutures.ConclusionUVR-B exposure of double cataract threshold dose induces a subtotal loss of epithelial cells across the whole anterior surface of the lens. This damage to the epithelium is repaired by epithelial cell movement from the equator towards the lens sutures, thus in retrograde direction to regular epithelial cell differentiation.
TL;DR: Transmission electron microscopy analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway, providing new insight into interactions between flaviviruses and cells.
Abstract: The intracellular morphogenesis of flaviviruses has been well described, but flavivirus release from the host cell remains poorly documented. We took advantage of the optimized production of an attenuated chimeric yellow fever/dengue virus for vaccine purposes to study this phenomenon by microscopic approaches. Scanning electron microscopy (SEM) showed the release of numerous viral particles at the cell surface through a short-lived process. For transmission electron microscopy (TEM) studies of the intracellular ultrastructure of the small number of cells releasing viral particles at a given time, we developed a new correlative microscopy method: CSEMTEM (for correlative scanning electron microscopy - transmission electron microscopy). CSEMTEM analysis suggested that chimeric flavivirus particles were released as individual particles, in small exocytosis vesicles, via a regulated secretory pathway. Our morphological findings provide new insight into interactions between flaviviruses and cells and demonstrate that CSEMTEM is a useful new method, complementary to SEM observations of biological events by intracellular TEM investigations.
TL;DR: Thelohanellus wuhanensis Xiao & Chen, 1993 infects allogynogenetic gibel carp Carassius auratus gibelio (Bloch) forming numerous plasmodia in the skin, resulting in high mortality of juvenile host fish, with information on its ultrastructural and histological characteristics added.
TL;DR: The morphology, histochemistry, and ultrastructure of foliar mucilage-producing trichomes of Harpagophytum procumbens are investigated using a combination of light and electron microscopy.
Abstract: The morphology, histochemistry, and ultrastructure of foliar mucilage-producing trichomes of Harpagophytum procumbens are investigated using a combination of light and electron microscopy. The leaves of H. procumbens bear short and long glandular trichomes comprising 1 or 2 basal epidermal cells, a stalk of 1-3 cells, a short neck cell, and a head of 2-5 cells. These trichomes are distributed on both leaf sides with a greater abundance on the abaxial side. Both types of trichomes secrete copious amounts of secretion as droplets onto the leaf surface, and the release occurs through micropores in the head cuticles. The secreted material is mainly constituted of mucilaginous polysaccharides, in addition to phenolic compounds and total lipids. The stalk surfaces of long trichomes are densely covered by numerous micropapillae helping the mucilage droplets to slide onto the leaf surface. The short and long trichomes have a similar ultrastructure: the secretory head cells are cytoplasmically dense due to the abundance of mitochondria, ribosomes, small vacuoles, plastids, Golgi bodies, and elements of endoplasmic reticulum. Golgi-derived vesicles are developed in the head cells, and each plastid contains large starch grains.
TL;DR: Healthy SF has a discontinuous ultrastructure based on a complex network of microvesicles, which offers novel perspectives for the diagnosis and treatment of synovial joint diseases.
Abstract: A better knowledge of synovial fluid (SF) ultrastructure is required to further understand normal joint lubrication and metabolism. The aim of the present study was to elucidate SF structural features in healthy joints from three mammalian species of different size compared with features in biomimetic SF. High-resolution structural analysis was performed using transmission electron microscopy (TEM) and scanning electron microscopy (SEM) and environmental SEM/wet scanning transmission electron microscopy mode complemented by TEM and SEM cryogenic methods. Laser-scanning confocal microscopy (LCM) was used to locate the main components of SF with respect to its ultrastructural organization. The present study showed that the ultrastructure of healthy SF is built from a network of vesicles with a size range from 100 to a few hundred nanometers. A multilayered organization of the vesicle membranes was observed with a thickness of about 5 nm. LCM study of biological SF compared with synthetic SF showed that the microvesicles consist of a lipid-based membrane enveloping a glycoprotein gel. Thus, healthy SF has a discontinuous ultrastructure based on a complex network of microvesicles. This finding offers novel perspectives for the diagnosis and treatment of synovial joint diseases.
TL;DR: The ultrastructure of Viridiraptor invadens has been studied by transmission and scanning electron microscopy in this paper, revealing ultrastructural traits that agree with the phylogenetic placement of the viridirus within Glissomonadida.
TL;DR: The study concludes that Pb2+ treatment caused structural anomalies and induced anatomical and surface ultrastructural changes in T. aestivum.
Abstract: Lead (Pb) causes severe damage to crops, ecosystems, and humans, and alters the physiology and biochemistry of various plant species. It is hypothesized that Pb-induced metabolic alterations could manifest as structural variations in the roots of plants. In light of this, the morphological, anatomical, and ultrastructural variations (through scanning electron microscopy, SEM) were studied in 4-day-old seedlings of Triticum aestivum grown under Pb stress (0, 8, 16, 40, and 80 mg Pb2+ l−1; mild to highly toxic). The toxic effect was more pronounced in radicle growth than on the plumule growth. The SEM of the root of T. aestivum depicted morphological alterations and surface ultrastructural changes. Compared to intact and uniform surface cells in the control roots, cells were irregular and desiccated in Pb2+-treated roots. In Pb2+-treated roots, the number of root hairs increased manifold, showing dense growth, and these were apparently longer. Apart from the deformity in surface morphology and anatomy of the roots in response to Pb2+ toxicity, considerable anatomical alterations were also observed. Pb2+-treated root exhibited signs of injury in the form of cell distortion, particularly in the cortical cells. The endodermis and pericycle region showed loss of uniformity post Pb2+ exposure (at 80 mg l−1 Pb2+). The cells appeared to be squeezed with greater depositions observed all over the tissue. The study concludes that Pb2+ treatment caused structural anomalies and induced anatomical and surface ultrastructural changes in T. aestivum.
TL;DR: It is concluded from this regression equation and from the results that the growth of Ch.
TL;DR: It is assumed that most of the observed structural and functional changes are adaptive, and meant to support the photosynthetic function and promote the cold tolerance of the plants.
Abstract: The effects of root chilling (2 °C; during 1, 5 h, 1, 2, 4 and 7 days) on the ultrastructure, functional activity of chloroplasts and cold tolerance of leaf cells of wheat (Triticum aestivum L.) were studied. Results indicated that the area of the chloroplasts increased and the number of grana in the chloroplast decreased already within first hours of the experiment. On the 2nd–7th day of the cold treatment, the length of photosynthetic membranes in the chloroplasts increased owing to the membranes of thylakoids in grana. The number of chloroplasts per cell was increased by the end of the experiment. Reduction of electron transport rate and intensification of non-photochemical quenching of chlorophyll fluorescence were observed in the first hours of root chilling. The growth of the leaves slowed in the first day of the treatment and resumed on the second day. Leaf area in the root-chilled plants by the end of the experiment exceeded the initial values by 60 %. The significant rise in cold tolerance of leaf cells was detected after 24 h of root chilling. After 48 h of the treatment, the cold tolerance reached a maximum, and did not change thereafter. It is assumed that most of the observed structural and functional changes are adaptive, and meant to support the photosynthetic function and promote the cold tolerance of the plants.