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Orchidaceae display enormous diversity in their flower morphology, which is particularly evident in their pollen dispersal units (pollinia, pollinaria). The packaging of pollen by elastoviscin leads to a great diversity of these morphologically and structurally complex pollen units. Despite being one of the most diverse angiosperm families, the available palynological data on orchids remain limited and sometimes contradicting. This study provides new insights into the pollen morphology and ultrastructure of five orchid species from the subfamily Epidendroideae, using combined light, scanning electron, and transmission electron microscopy. The aim was to compare the morphology and ultrastructure of pollen dispersal units and to elucidate the chemical nature of the pollen wall layers and of elastoviscin. Our combined light and electron microscopy investigation demonstrated the presence of six tetrad types even within a single pollinium, which is unique for orchids. The application of different staining methods confirmed the assumed lipidic nature of elastoviscin and the differences in its contrast and ultrastructure suggest a mixture of sticky materials with dissimilar chemical compositions. This study affirmed that sporopollenin is mostly restricted to the outer pollen grains of peripheral tetrads in compact and sectile pollinia, while inner tetrads exhibit highly reduced non-sporopollenin pollen walls. [ABSTRACT FROM AUTHOR]

Elucidating the 3D nanoscale structure of tissues and cells is essential for understanding the complexity of biological processes. Electron microscopy (EM) offers the resolution needed for reliable interpretation, but the limited throughput of electron microscopes has hindered its ability to effectively image large volumes. We report a workflow for volume EM with FAST-EM, a novel multibeam scanning transmission electron microscope that speeds up acquisition by scanning the sample in parallel with 64 electron beams. FAST-EM makes use of optical detection to separate the signals of the individual beams. The acquisition and 3D reconstruction of ultrastructural data from multiple biological samples is demonstrated. The results show that the workflow is capable of producing large reconstructed volumes with high resolution and contrast to address biological research questions within feasible acquisition time frames. [ABSTRACT FROM AUTHOR]

Freeze substitution is a crucial technique in electron microscopy, enabling the preservation of biological specimen ultrastructure. However, existing tools are primarily designed for 3 mm carriers, limiting their compatibility with larger carriers such as CryoCapsules or 6 mm carriers. In this study, we developed a novel freeze substitution tool, simply named the FS-basket, to address the challenges associated with embedding samples vitrified in larger carriers. The tool comprises a mesh with pore sizes smaller than the sample chunks, deposited below the carrier to maintain a tight seal while allowing for easy fluid exchange. [ABSTRACT FROM AUTHOR]

The seta and stem in Leucodon canariensis are examined by means of light microscopy, transmission and scanning electron microscopy. Their anatomies reveal relevant differences although both show a remarkable structural complexity, as their conducting tissues are equally effective in carrying out essential processes. Five types of cells have been recognized in the transverse sections: in both seta and stem: (i) stereids in the external region with a peripheral cuticle; in the stem only: (ii) parenchymatous cells with plasmodesmata underlying the stereids; in the seta only: (iii) an unusual area of nacreous-walled cells without live protoplasm, surrounding (iv) the food-conducting cells (leptoid-like), and again both in seta and stem: (v) hydroids in the internal region. The seta in this species has a peculiar organization and shares some characteristics with polytrichaceous mosses; the ultrastructural similarities and differences and functional significance of these cells are discussed, both systematically and in relation to the habit of the moss itself. [ABSTRACT FROM AUTHOR]

Understanding the complexity of cellular function within a tissue necessitates the combination of multiple phenotypic readouts. Here, we developed a method that links spatially-resolved gene expression of single cells with their ultrastructural morphology by integrating multiplexed error-robust fluorescence in situ hybridization (MERFISH) and large area volume electron microscopy (EM) on adjacent tissue sections. Using this method, we characterized in situ ultrastructural and transcriptional responses of glial cells and infiltrating T-cells after demyelinating brain injury in male mice. We identified a population of lipid-loaded "foamy" microglia located in the center of remyelinating lesion, as well as rare interferon-responsive microglia, oligodendrocytes, and astrocytes that co-localized with T-cells. We validated our findings using immunocytochemistry and lipid staining-coupled single-cell RNA sequencing. Finally, by integrating these datasets, we detected correlations between full-transcriptome gene expression and ultrastructural features of microglia. Our results offer an integrative view of the spatial, ultrastructural, and transcriptional reorganization of single cells after demyelinating brain injury. To understand complexity of cellular function, multiple phenotypic readouts are needed. Here, authors devised an approach integrating location, transcriptome, ultrastructure, and lipid content to characterize single-cell states after brain injury. [ABSTRACT FROM AUTHOR]

Bioluminescence is a common ecological trait among many marine organisms, including three shark families: Etmopteridae, Dalatiidae, and Somniosidae. The kitefin shark, Dalatias licha (Bonnaterre, 1788), from the Dalatiidae family is the largest known luminous vertebrate. This study compares the light organ ultrastructure of D. licha with that of Etmopterus spinax, the type species of Etmopteridae, to gain a deeper understanding of the light emission process and its evolutionary conservation within shark families. The ultrastructure of D. licha's photophores and the morphological changes that occur after hormonal stimulation (via melatonin and α-MSH, which stimulate or inhibit the bioluminescence, respectively) were examined. The photophores consist of a spherical pigmented sheath surrounding a unique, regionalized light-emitting cell (photocyte). The photocyte's basal area contains a specific area filled with granular inclusions that resemble the glowon-type microsources of E. spinax, suggesting that this area is the intracellular site of light emission. An acidophilic secretion, not present in Etmopteridae, is also observed within the granular area and may be involved in photogenesis. The ultrastructure analysis reveals no lens cells or reticular layer, unlike in Etmopteridae photophores, indicating a simpler organization in Dalatiidae photophores. Melatonin stimulation causes the removal of pigments from the photophore-associated melanophores and an increase in the granular inclusion diameter and coverage in the granular area, further showing that this last area is the potential site of light emission, while α-MSH stimulation causes the extension of the melanophore pigments and a decrease in the granular inclusion diameter and coverage. These results support the evolutive conservation of photophore functional organization across luminous etmopterid and dalatiid sharks. [ABSTRACT FROM AUTHOR]

Leishmaniasis represents a serious world health problem, with 1 billion people being exposed to infection and a broad spectrum of clinical manifestations with a potentially fatal outcome. Based on the limitations observed in the treatment of leishmaniasis, such as high cost, significant adverse effects, and the potential for drug resistance, the aim of the present study was to evaluate the leishmanicidal activity of the compounds pseurotin A and monomethylsulochrin isolated from the biomass extract of Aspergillus sp. The chromatographic profiles of the extract were determined by high-performance liquid chromatography coupled with a diode-array UV-Vis detector (HPLC-DAD-UV), and the molecular identification of the pseurotin A and monomethylsulochrin were carried out by electrospray ionization mass spectrometry in tandem (LC-ESI-MS-MS) and nuclear magnetic resonance (NMR). Antileishmanial activity was assayed against promastigote and intracellular amastigote of Leishmania amazonensis. As a control, cytotoxicity assays were performed in non-infected BALB/c peritoneal macrophages. Ultrastructural alterations in parasites were evaluated by transmission electron microscopy. Changes in mitochondrial membrane potential were determined by flow cytometry. Only monomethylsulochrin inhibited the promastigote growth (IC50 18.04 ± 1.11 µM), with cytotoxicity to peritoneal macrophages (CC50 5.09 91.63 ± 1.28 µM). Activity against intracellular amastigote forms (IC50 5.09 ± 1.06 µM) revealed an increase in antileishmanial activity when compared with promastigotes. In addition to a statistically significant reduction in the evaluated infection parameters, monomethylsulochrin altered the ultrastructure of the promastigote forms with atypical vacuoles, electron-dense corpuscles in the cytoplasm, changes at the mitochondria outer membrane and abnormal disposition around the kinetoplast. It was showed that monomethylsulochrin leads to a decrease in the mitochondrial membrane potential (25.9%, p = 0.0286). Molecular modeling studies revealed that monomethylsulochrin can act as inhibitor of sterol 14-alpha-demethylase (CYP51), a therapeutic target for human trypanosomiasis and leishmaniasis. Assessed for its drug likeness, monomethylsulochrin follows the Lipinski Rule of five and Ghose, Veber, Egan, and Muegge criteria. Furthermore, monomethylsulochrin can be used as a reference in the development of novel and therapeutically useful antileishmanial agents. [ABSTRACT FROM AUTHOR]

The neurotoxins methamphetamine (METH) and 1-methyl-4-phenylpyridinium (MPP+) damage catecholamine neurons. Although sharing the same mechanism to enter within these neurons, METH neurotoxicity mostly depends on oxidative species, while MPP+ toxicity depends on the inhibition of mitochondrial activity. This explains why only a few compounds protect against both neurotoxins. Identifying a final common pathway that is shared by these neurotoxins is key to prompting novel remedies for spontaneous neurodegeneration. In the present study we assessed whether natural extracts from Bacopa monnieri (BM) may provide a dual protection against METH- and MPP+-induced cell damage as measured by light and electron microscopy. The protection induced by BM against catecholamine cell death and degeneration was dose-dependently related to the suppression of reactive oxygen species (ROS) formation and mitochondrial alterations. These were measured by light and electron microscopy with MitoTracker Red and Green as well as by the ultrastructural morphometry of specific mitochondrial structures. In fact, BM suppresses the damage of mitochondrial crests and matrix dilution and increases the amount of healthy and total mitochondria. The present data provide evidence for a natural compound, which protects catecholamine cells independently by the type of experimental toxicity. This may be useful to counteract spontaneous degenerations of catecholamine cells. [ABSTRACT FROM AUTHOR]

A primary cilium is a membrane-bound extension from the cell surface that contains receptors for perceiving and transmitting signals that modulate cell state and activity. Primary cilia in the brain are less accessible than cilia on cultured cells or epithelial tissues because in the brain they protrude into a deep, dense network of glial and neuronal processes. Here, we investigated cilia frequency, internal structure, shape, and position in large, high-resolution transmission electron microscopy volumes of mouse primary visual cortex. Cilia extended from the cell bodies of nearly all excitatory and inhibitory neurons, astrocytes, and oligodendrocyte precursor cells (OPCs) but were absent from oligodendrocytes and microglia. Ultrastructural comparisons revealed that the base of the cilium and the microtubule organization differed between neurons and glia. Investigating cilia-proximal features revealed that many cilia were directly adjacent to synapses, suggesting that cilia are poised to encounter locally released signaling molecules. Our analysis indicated that synapse proximity is likely due to random encounters in the neuropil, with no evidence that cilia modulate synapse activity as would be expected in tetrapartite synapses. The observed cell class differences in proximity to synapses were largely due to differences in external cilia length. Many key structural features that differed between neuronal and glial cilia influenced both cilium placement and shape and, thus, exposure to processes and synapses outside the cilium. Together, the ultrastructure both within and around neuronal and glial cilia suggest differences in cilia formation and function across cell types in the brain. [Display omitted] • Primary cilia extend from visual cortex neurons and select glia • Internal cilia ultrastructure is not stereotyped but varies between cell classes • Cilia are near synapses and surrounded by neurites and glial processes • Cilia placement and structure impact the external environment of cilia Ott and Torres et al. identify distinguishing anatomical features of neuronal and glial primary cilia in the mouse visual cortex. Internal structural differences determine both cilium shape and the extent of cilium exposure to the extracellular neuropil, where cilia pass near, and even adjacent to, many synapses. [ABSTRACT FROM AUTHOR]

The history of the development and use of low-temperature electron microscopic methods of freeze-fracture, freeze-substitution and others in cryobiological research at the Institute for Problems of Cryobiology and Cryomedicine of the National Academy of Sciences of Ukraine is presented in this article. These methods' possibilities in studying the processes of crystal formation in cryoprotectant solutions, cell suspensions, and tissues under various freezing conditions are demonstrated. Some results of the analysis of ultrastructural changes in biological systems of various organization levels, at different stages of ontogenesis, under the influence of cooling in a wide temperature range (from 37 to -196°C) are presented. The use of a high resolution electron microscopic method in combination with an accessory technical equipment and some methodological techniques allowed to obtain fundamental results important for cryobiology on ice crystals formation and localization in the intracellular volume, the temperature-dependent transmembrane proteins redistribution, changes in the ultrastructure of erythrocytes and their membranes during hypothermic storage. [ABSTRACT FROM AUTHOR]

We have previously indicated that a single injection of alendronate, one of the nitrogen-containing bisphosphonates (NBPs), affects murine hematopoietic processes, such as the shift of erythropoiesis from bone marrow (BM) to spleen, disappearance of BM-resident macrophages, the increase of granulopoiesis in BM and an increase in the number of osteoclasts. NBPs induce apoptosis and the formation of giant osteoclasts in vitro and/or in patients undergoing long-term NBP treatment. Therefore, the time-kinetic effect of NBPs on osteoclasts needs to be clarified. In this study, we examined the effect of alendronate on mouse osteoclasts and osteoclastogenesis. One day after the treatment, osteoclasts lost the clear zone and ruffled borders, and the cell size decreased. After 2 days, the cytoplasm of osteoclasts became electron dense and the nuclei became pyknotic. Some of the cells had fragmented nuclei. After 4 days, osteoclasts had euchromatic nuclei attached to the bone surface. Osteoclasts had no clear zones or ruffled borders. After 7 days, osteoclasts formed giant osteoclasts via the fusion of multinuclear and mononuclear osteoclasts. These results indicate that NBPs affect osteoclasts and osteoclastogenesis via two different mechanisms. [ABSTRACT FROM AUTHOR]

As a topographical technique, Atomic Force Microscopy (AFM) needs to establish direct interactions between a given sample and the measurement probe in order to create imaging information. The elucidation of internal features of organisms, tissues and cells by AFM has therefore been a challenging process in the past. To overcome this hindrance, simple and fast embedding, sectioning and dehydration techniques are presented, allowing the easy access to the internal morphology of virtually any organism, tissue or cell by AFM. The study at hand shows the applicability of the proposed protocol to exemplary biological samples, the resolution currently allowed by the approach as well as advantages and shortcomings compared to classical ultrastructural microscopic techniques like electron microscopy. The presented cheap, facile, fast and non-toxic experimental protocol might introduce AFM as a universal tool for the elucidation of internal ultrastructural detail of virtually any given organism, tissue or cell. [ABSTRACT FROM AUTHOR]

Modern morphological and structural studies are coming to a new level by incorporating the latest methods of three-dimensional electron microscopy (3D-EM). One of the key problems for the wide usage of these methods is posed by difficulties with sample preparation, since the methods work poorly with heterogeneous (consisting of tissues different in structure and in chemical composition) samples and require expensive equipment and usually much time. We have developed a simple protocol allows preparing heterogeneous biological samples suitable for 3D-EM in a laboratory that has a standard supply of equipment and reagents for electron microscopy. This protocol, combined with focused ion-beam scanning electron microscopy, makes it possible to study 3D ultrastructure of complex biological samples, e.g., whole insect heads, over their entire volume at the cellular and subcellular levels. The protocol provides new opportunities for many areas of study, including connectomics. [ABSTRACT FROM AUTHOR]

Gonocytes in the neonatal testis have male germline stem cell potential. The objective of the present study was to examine the behavior and ultrastructure of gonocytes in culture. Neonatal porcine testis cells were cultured for 4 weeks and underwent live-cell imaging to explore real-time interactions among cultured cells. This included imaging every 1 h from day 0 to day 3, every 2 h from day 4 to day 7, and every 1 h for 24 h at days 14, 21, and 28. Samples also underwent scanning electron microscopy, transmission electron microscopy, morphometric evaluations, immunofluorescence, and RT-PCR. Live-cell imaging revealed an active amoeboid-like movement of gonocytes, assisted by the formation of extensive cytoplasmic projections, which, using scanning electron microscopy, were categorized into spike-like filopodia, leaf-like lamellipodia, membrane ruffles, and cytoplasmic blebs. In the first week of culture, gonocytes formed loose attachments on top of a somatic cell monolayer and, in week 2, formed grape-like clusters, which, over time, grew in cell number. Starting at week 3 of culture, some of the gonocyte clusters transformed into large multinucleated embryoid body–like colonies (EBLCs) that expressed both gonocyte- and pluripotent-specific markers. The number and diameter of individual gonocytes, the number and density of organelles within gonocytes, as well as the number and diameter of the EBLCs increased over time (P < 0.05). In conclusion, cultured porcine gonocytes displayed extensive migratory behavior facilitated by their various cytoplasmic projections, propagated, and transformed into EBLCs that increased in size and complexity over time. [ABSTRACT FROM AUTHOR]

Endornaviruses include viruses that infect fungi, oomycetes, and plants. The genome of plant endornaviruses consists of linear ssRNA ranging in size from approximately 13-18 kb and lacking capsid protein and cell-to-cell movement capability. Although, plant endornaviruses have not been shown to cause detectable changes in the plant phenotype, they have been associated with alterations of the host physiology. Except for the association of cytoplasmic vesicles with infections by Vicia faba endornavirus, effects on the plant cell ultrastructure caused by endornaviruses have not been reported. Bell pepper endornavirus (BPEV) has been identified in several pepper (Capsicum spp.) species. We conducted ultrastructural analyses of cells from two near-isogenic lines of the bell pepper (C. annuum) cv. Marengo, one infected with BPEV and the other BPEV-free, and found cellular alterations associated with BPEV-infections. Some cells of plants infected with BPEV exhibited alterations of organelles and other cell components. Affected cells were located mainly in the mesophyll and phloem tissues. Altered organelles included mitochondrion, chloroplast, and nucleus. The mitochondria from BPEV-infected plants exhibited low number of cristae and electron-lucent regions. Chloroplasts contained plastoglobules and small vesicles in the surrounding cytoplasm. Translucent regions in thylakoids were observed, as well as hypertrophy of the chloroplast structure. Many membranous vesicles were observed in the stroma along the envelope. The nuclei revealed a dilation of the nuclear envelope with vesicles and perinuclear areas. The organelle changes were accompanied by membranous structure rearrangements, such as paramural bodies and multivesicular bodies. These alterations were not observed in cells from plants of the BPEV-free line. Overall, the observed ultrastructural cell alterations associated with BPEV are similar to those caused by plant viruses and viroids and suggest some degree of parasitic interaction between BPEV and the plant host. [ABSTRACT FROM AUTHOR]

The ultrastructural morphology of the bovine oocyte at different maturation stages has been previously analyzed but without detailed structural observations at the mature stage. The objective of the present study was thus to establish the ultrastructural characteristics of the mature bovine oocyte in full detail. Oocytes from Bos taurus (Holstein-Friesian) cows were aspirated from ovaries collected after being slaughtered at a local abattoir. After in vitro culture for 24 h, some of them were processed for electron microscopy. We described the ultrastructure of the zona pellucida, which presented three different regions, and novel cytoplasmic findings. There were two types of electron-lucent vesicles (heterogeneous and striated), which were suggested to give rise to lipid droplets, and presence of receptor-mediated endocytosis. In conclusion, our results indicate that although the mature bovine oocyte is devoid of evident yolk, it might be filled with an extensive lipid factory. In addition, even before fertilization, the mature oocyte seemed to absorb nutrients through receptor-mediated endocytosis, indicating active energy use or storage. Ultrastructure of mature oocytes. Detail of lipid droplets. A. Lipid droplet containing thin dense filaments (arrowhead), which confers a striated (fractured) appearance (sL). B. Lipid droplet encircled by layers of thin dense filaments (arrowhead), which confers a circular appearance (L). Scale bars: 0.5 μm. Image 1 • The bovine zona pellucida presented three different regions. • Heterogeneous and striated vesicles, seem to behave as lipid factories. • The bovine mature oocyte presents receptor-mediated endocytosis. [ABSTRACT FROM AUTHOR]

Analysis of neuronal compartments has revealed many state-dependent changes in geometry but establishing synapse-specific mechanisms at the nanoscale has proven elusive. We co-expressed channelrhodopsin2-GFP and mAPEX2 in a subset of hippocampal CA3 neurons and used trains of light to induce late-phase long-term potentiation (L-LTP) in area CA1. L-LTP was shown to be specific to the labeled axons by severing CA3 inputs, which prevented back-propagating recruitment of unlabeled axons. Membrane-associated mAPEX2 tolerated microwave-enhanced chemical fixation and drove tyramide signal amplification to deposit Alexa Fluor dyes in the light-activated axons. Subsequent post-embedding immunogold labeling resulted in outstanding ultrastructure and clear distinctions between labeled (activated), and unlabeled axons without obscuring subcellular organelles. The gold-labeled axons in potentiated slices were reconstructed through serial section electron microscopy; presynaptic vesicles and other constituents could be quantified unambiguously. The genetic specification, reliable physiology, and compatibility with established methods for ultrastructural preservation make this an ideal approach to link synapse ultrastructure and function in intact circuits. [ABSTRACT FROM AUTHOR]

Recent super-resolution microscopy studies have unveiled a periodic scaffold of actin rings regularly spaced by spectrins under the plasma membrane of axons. However, ultrastructural details are unknown, limiting a molecular and mechanistic understanding of these enigmatic structures. Here, we combine platinum-replica electron and optical super-resolution microscopy to investigate the cortical cytoskeleton of axons at the ultrastructural level. Immunogold labeling and correlative super-resolution/electron microscopy allow us to unambiguously resolve actin rings as braids made of two long, intertwined actin filaments connected by a dense mesh of aligned spectrins. This molecular arrangement contrasts with the currently assumed model of actin rings made of short, capped actin filaments. Along the proximal axon, we resolved the presence of phospho-myosin light chain and the scaffold connection with microtubules via ankyrin G. We propose that braided rings explain the observed stability of the actin-spectrin scaffold and ultimately participate in preserving the axon integrity. The ultrastructural details of the periodic scaffold of actin rings under the plasma membrane of axons remain unknown. Here, the authors combine platinum-replica electron and optical super-resolution microscopy and resolve actin rings as braids made of two long, intertwined actin filaments connected by a dense mesh of aligned spectrins. [ABSTRACT FROM AUTHOR]

• Different stages of spermatogenesis process in Burbot, Lota lota was described. • Three distinct stages of cell differentiation can be identified during spermiogenesis. • Spermiogenesis stages are characterised by three distinct morphological changes. Testis development and ultrastructure of spermatogenic cells and spermatozoa of burbot Lota lota , a commercially important cold freshwater fish, were studied by light and transmission electron microscopy. Spermatogonia, spermatocytes, spermatids, and spermatozoa are distributed along the seminiferous tubules. Electron-dense bodies appear in germ cells from primary spermatogonia to secondary spermatocytes. We identified three distinct stages of spermatid cell differentiation based on chromatin condensation, development of the flagellum, formation of a nuclear fossa, and elimination of excess cytoplasm. Spermatozoa were anacrosomal and characterized by location of the centrioles outside the nuclear fossa and incomplete perpendicular arrangement of the centrioles. The sperm flagellum displayed an axoneme with nine doublets of peripheral microtubules and two central microtubules. These results provide valuable information for burbot taxonomy and may clarify the process of spermatogenesis for this species. [ABSTRACT FROM AUTHOR]

Background and objectives: Hepatocyte ultra-structure is influenced by feeding status, circadian rhythm, and zone location. The goal of the present study was to study the effect of overnight fasting on the hepatocyte ultrastructure and the zonal heterogeneity and to discuss the functional correlation. Methods: A total of 14 male albino rats were divided into two groups: negative control group fed ad libitum and overnight fasting rats for 16 hours. The different subcellular structures of both centrilobular and periportal hepatocytes in both control and fasted groups were compared by transmission electron microscopy. Morphometric analysis of the electron micrographs was also done using imageJ software. Results: The lysosomes surface density, mitochondrial volume and surface densities were significantly higher in periportal hepatocytes however surface density of smooth endoplasmic reticulum (SER) and peroxisomes were significantly higher in centrilobular hepatocytes of the control group. Fasting caused a significant decrease in the surface density of rough endoplasmic reticulum and glycogen volume density but with significant increase in SER surface density with more mitochondrial fusion and stronger mitochondrial ER contacts, isolation membranes, and autophagosomes. The zonal differences were maintained after fasting. The organelles appeared normal with no signs of degeneration. Conclusion: The organelles appeared normal with no signs of degeneration and the zonal differences were maintained after fasting. The change in hepatocyte ultrastructure after fasting may be related to autophagy. [ABSTRACT FROM AUTHOR]

Ministeria vibrans (Filasterea) is a tiny amoeboid species described by Tong in 1997. It has been sporadically found in different habitats, and cultured strains were established. M. vibrans is well characterised by molecular phylogeny but until now was not ultrastructurally investigated in detail. Here, we provide the ultrastructure for this species based on a new strain isolated from oxygen-depleted water of the Baltic Sea. A thin vibrating flagellum could be observed but no vibrating movement of the cell body and no stalk. Our first ultrastructural study of a filasterean taxon revealed radial microvilli supported by bundles of microfilaments. Two centrioles located in the nuclear pit can migrate to the cell periphery and transform into the kinetid: the centriole orthogonal to the kinetosome with a fibrillar root and a basal foot that initiates microtubules. Microvilli in Ministeria suggest their presence in the common ancestor of Filasterea and Choanoflagellata. The kinetid structure of Ministeria is similar to that of the choanocytes of the most deep-branching sponges, differing essentially from the kinetid of choanoflagellates. Thus, kinetid and microvilli of Ministeria illustrate features of the common ancestor of three holozoan groups: Filasterea, Metazoa and Choanoflagellata. [ABSTRACT FROM AUTHOR]

The normal aging of the extracellular matrix and collagen content of the human lumbar intervertebral disc (IVD) remains relatively unknown despite vast amounts of basic science research, partly because of the use of inadequate surrogates for a truly normal, human IVD. Our objective in this study was to describe and compare the morphology and ultrastructure of lumbar IVDs in 2 groups of young (G1—<35 years) and elderly (G2—>65 years). Thirty L4-5 and L5-S1 discs per group were obtained during autopsies of presumably-asymptomatic individuals and analyzed with magnetic resonance imaging (MRI), a morphological grading scale, light microscopy, scanning electron microscopy (SEM) and immunohistochemistry (IHC) for collagen types I, II, III, IV, V, VI, IX and X. As expected, a mild to moderate degree of degeneration was present in G1 discs and significantly more advanced in G2. The extracellular matrix of G2 discs was significantly more compact with an increase of cartilaginous features such as large chondrocyte clusters. Elastic fibers were abundant in G1 specimens and their presence correlated more with age than with degeneration grade, being very rare in G2. SEM demonstrated persistence of basic structural characteristics such as denser lamellae with Sharpey-type insertions into the endplates despite advanced age or degeneration grades. Immunohistochemistry revealed type II collagen to be the most abundant type followed by collagen IV. All collagen types were detected in every disc sector except for type X collagen. Statistical analysis demonstrated a general decrease in collagen expression from G1 to G2 with an annular- and another nuclear-specific pattern. These results suggest modifications of IVD morphology do not differ between the anterior or posterior annulus but are more advanced or happen earlier in the posterior areas of the disc. This study finally describes the process of extracellular matrix modification during disc degeneration in an unselected, general population and demonstrates it is similar to the same process in the cervical spine as published previously. [ABSTRACT FROM AUTHOR]

Many myodocopid ostracods are unusual in that they have well-developed compound eyes yet must view their environment through a shell. The cypridinid Macrocypridina castanea is relatively large among ostracods (about 5–10mm) and is a pelagic predator. This species possess highly pigmented shells with a transparent region lying just above the eye. Here we examine the ultrastructure and transparency of this window using electron microscopy, serial-block face scanning electron microscopy and X-ray diffraction analysis and optical modelling. An internal, laminar stack was identified within the window region of the shell that formed a more regular half-wave reflector than in non-window regions, and where the distance between molecules in the chitin–protein fibrils decreases as compared to the non-window area. This results in excellent transmission properties— at around 99% transmission—for wavelengths between 350 and 630nm due to its half-wave reflector organization. Therefore, blue light, common in the mid and deep sea, where this species inhabits, would be near-optimally transmitted as a consequence of the sub-micrometre structuring of the shell, thus optimizing the ostracod’s vision. Further, pore canals were identified in the shell that may secrete substances to prevent microbial growth, and subsequently maintain transparency, on the shell surface. [ABSTRACT FROM AUTHOR]

The ultrastructure of bone has been widely debated, in part due to limitations in visualizing nanostructural features over relevant micrometer length scales. Here, we employ the high resolving power and compositional contrast of high-angle annular dark-field scanning transmission electron microscopy (HAADF STEM) to investigate new features in human bone with nanometer resolution over microscale areas. Using focused ion beam (FIB)-milled sections that span an area of 50 μm2, we have shown how most of the mineral of cortical human osteonal bone occurs in the form of long, thin polycrystalline plates (mineral lamellae, MLs) which are either flat or curved to wrap closely around collagen fibrils. Close to the collagen fibril (< 20 nm), the radius of curvature matches that of the fibril diameter, while at greater distances, MLs form arcs with much larger radii of curvature. In addition, stacks of closely packed planar (uncurved) MLs occur between fibrils. The curving of mineral lamellae both around and between the fibrils would contribute to the strength of bone. At a larger scale, rosette-like clusters of fibrils are noted for the first time, arranged in quasi-circular arrays that define tube-like structures in alternating osteonal lamellae. At the boundary between adjacent osteonal lamellae, the orientation of fibrils and surrounding mineral lamellae changes abruptly, resembling the "orthogonal" patterns identified by others (Reznikov et al. in Acta Biomater 10:3815-3826, 2014). These features spanning nanometer to micrometer scale have implications for our understanding of bone structure and mechanical integrity. [ABSTRACT FROM AUTHOR]

Abstract Introduction We evaluated the morphology of amyloid fibrils in the peripheral nervous system using biopsy or autopsy specimens from hereditary transthyretin amyloidosis patients. The impact of amyloid fibril formation on neighboring tissues was also investigated. Methods Sural nerve biopsy specimens from 34 patients were examined using electron microscopy. Twenty-eight patients had Val30Met mutations, and the remaining 6 patients had non-Val30Met mutations (i.e., Glu54Lys, Pro24Ser, Thr49Ala, Val71Ala, Val94Gly, and Ala97Gly). The patients with the Val30Met mutation included a case from Brazil (supposedly of Portuguese origin), 6 early-onset cases from endemic foci in Japan, and 21 late-onset cases from non-endemic areas in Japan. Results Long amyloid fibers were abundant in the early-onset Val30Met cases from the Japanese endemic foci and Brazil, whereas the amyloid fibrils were generally short in the late-onset Val30Met and non-Val30Met cases. The amyloid fibrils seemed to mature from dotty structures among amorphous electron-dense extracellular materials and pull surrounding tissues during the maturation process. The distortion of Schwann cells close to amyloid fibril masses was conspicuous, particularly in cases with long amyloid fibrils. Atrophy was conspicuous in non-myelinating Schwann cells and bands of Büngner (i.e., Schwann cell subunits that previously contained myelinated axons), particularly those completely surrounded by amyloid fibrils. In contrast, the myelinated fibers tended to be only partially surrounded by amyloid fibrils and morphologically preserved due to their large size. Only a few demyelinated axons were found. Conclusion Pre-fibrillar amyloid precursors appear to play a pivotal role during the initial phase of amyloid fibril formation. The mechanical distortion and subsequent atrophy of Schwann cells resulting from the elongation of amyloid fibrils may be related to small-fiber predominant loss, which is a classical characteristic of amyloid neuropathy. Although rather rare, the destruction of myelin (i.e., demyelination) resulting from amyloid deposition may relate to nerve conduction abnormalities mimicking chronic inflammatory demyelinating polyneuropathy. Highlights • Morphology of amyloid fibrils was different depending on individual patients. • Amyloid fibrils seemed to mature from dotty structures among amorphous materials. • Distortion of Schwann cells due to the elongation of amyloid fibrils was observed. • Distortion and subsequent atrophy of Schwann cells may relate to nerve fiber loss. [ABSTRACT FROM AUTHOR]

Plasma membrane rupture can result in catastrophic cell death. The skeletal muscle fiber plasma membrane, the sarcolemma, provides an extreme example of a membrane subject to mechanical stress since these cells specifically evolved to generate contraction and movement. A quantitative model correlating ultrastructural remodeling of surface architecture with tissue changes in vivo is required to understand how membrane domains contribute to the shape changes associated with tissue deformation in whole animals. We and others have shown that loss of caveolae, small invaginations of the plasma membrane particularly prevalent in the muscle sarcolemma, renders the plasma membrane more susceptible to rupture during stretch. 1,2,3 While it is thought that caveolae are able to flatten and be absorbed into the bulk membrane to buffer local membrane expansion, a direct demonstration of this model in vivo has been unachievable since it would require measurement of caveolae at the nanoscale combined with detailed whole-animal morphometrics under conditions of perturbation. Here, we describe the development and application of the "active trapping model" where embryonic zebrafish are immobilized in a curved state that mimics natural body axis curvature during an escape response. The model is amenable to multiscale, multimodal imaging including high-resolution whole-animal three-dimensional quantitative electron microscopy. Using the active trapping model, we demonstrate the essential role of caveolae in maintaining sarcolemmal integrity and quantify the specific contribution of caveolar-derived membrane to surface expansion. We show that caveolae directly contribute to an increase in plasma membrane surface area under physiologically relevant membrane deformation conditions. • "Active trapping" of zebrafish provides an in vivo model of membrane stretch • Membrane stretch results in disassembly of muscle caveolae • Genetic ablation of caveolae results in membrane rupture under stretch • Membrane released by disassembly matches that required for surface area expansion Animal cells can be subject to rapid and dramatic shape changes during growth, development, and normal function, but plasma membrane rupture results in catastrophic cell death. Hall et al. use a flexing fish model to show how muscle fibers under stretch buffer sarcolemmal tension using small membrane pits called caveolae. [ABSTRACT FROM AUTHOR]

The detection and identification of two endocytobiotic bacterial strains, one affiliated to the “Candidatus Caedibacter acanthamoebae”/“Ca. Paracaedimonas acanthamoeba”, and another to the endosymbiont of Acanthamoeba UWC8 and “Ca. Jidaibacter acanthamoeba” are described. For endocytobiont screening, we developed a PCR method with a set of broad-range bacterial 16S rRNA primers to substitute the commonly used but technically demanding fluorescent in situ hybridization technique. Our PCR test alone without sequencing failed to discriminate the endocytobiont-containing and endocytobiont-free Acanthamoeba sp. due to the presence of mismatched primers to host mitochondrial DNA. We highlighted the need to perform bacterial primer checking against the Acanthamoeba genome to avoid false positive detection in PCR. Although the genetic aspect of “Ca. Caedibacter acanthamoebae”/“Ca. Paracaedimonas acanthamoeba” and the endosymbiont of Acanthamoeba UWC8/“Ca. Jidaibacter acanthamoeba” are well studied, knowledge pertaining to their morphologies are quite vague. Hence, we used transmission electron microscopy to examine our endocytobionts which are affiliated to previously described intracellular bacteria of Acanthamoeba sp. We used good-quality TEM images for the localization and the fate of the current endocytobionts inside different life stages of the hosts. Furthermore, to the best of our knowledge, our TEM findings are the first to provide morphological evidence for the clearance of defective Acanthamoeba endocytobionts via an autophagic-like process. [ABSTRACT FROM AUTHOR]

At parallel fibre terminals in the cerebellar cortex, glutamate released outside of the active zone can activate AMPA receptors on juxtaposed Bergmann glial cell processes. This process is termed “ectopic” release, and allows for directed transmission to astroglial cells that is functionally independent of synaptic transmission to postsynaptic Purkinje neurons. The location of ectopic sites in presynaptic terminals is uncertain. Functional evidence suggests that stimulation of parallel fibres at 1 Hz exhausts ectopic transmission due to a failure to rapidly recycle vesicles to the ectopic pool, and so would predict a loss of vesicles in the near vicinity of extrasynaptic glial processes. In this study we used this stimulation protocol to investigate whether the distribution of vesicles within the presynaptic terminal is altered after suppression of ectopic release. Stimulation at 1 Hz had only a minor impact on the distribution of vesicles in presynaptic terminals when analysed with electron microscopy. Vesicle number and terminal size were unaffected by 1 Hz stimulation, but the relative abundance of vesicles in close proximity to the active zone was marginally reduced. In contrast, the fraction of vesicles facing glial membranes was unchanged after suppression of ectopic transmission. 1 Hz stimulation also resulted in a small but statistically-significant increase in the distance between glial membrane and presynaptic terminal, suggesting withdrawal of glial membranes from synapses is detectable in ultrastructural anatomy within minutes. These results raise doubts about the location of ectopic release sites, but indicate that neuron-glial association varies on a dynamic time scale. [ABSTRACT FROM AUTHOR]

The morphology and ultrastructure of the midgut of Gampsocleis gratiosa (Orthoptera: Tettigoniidae) was examined by light and electron microscopy. The midgut consists of two bulbous gastric caeca and a tubular ventriculus. The general organization of the gastric caeca is similar to that of the ventriculus. They are composed of a peritrophic membrane, an epithelium, a basal lamina and muscle layer from the inside to outside. Three types of cells were identified: regenerative, principal, and endocrine. Regenerative cells occur in groups (called nidi) at the base of principal cells. Principal cells grow from regenerative cells. Rare endocrine cells are scattered throughout the epithelium. Principal cells exhibit intense secretory activity, and regional differences in their ultrastructure were observed along the entire midgut. The microvilli are longer than those in any other region in the posterior region of the midgut. Lysosomes, multivesicular bodies (MVBs), autophagosomes, abundant Golgi apparatuses and lipid droplets primarily occur in the gastric caeca. Three pathways of secretion (merocrine, apocrine and holocrine) occur within the midgut epithelium, and a distinctive type of apocrine bleb was found in the gastric caeca. Therefore, these gastric caeca may be evolving toward a special type of gland. [ABSTRACT FROM AUTHOR]

The ultrastructure of the lophophoral coelomic lining in the articulate brachiopod Hemithiris psittacea was studied using electron microscopy and confocal laser scanning microscopy. The coelomic system of the lophophore consists of large and small canals; both extend along each brachium. A small coelomic canal gives rise to a blind coelomic canal into each tentacle. The lophophoral coelothelium consists of two types of cells, epithelio-muscle and peritoneal cells, and exhibits different types of organization that is known in the Bilateria: from an epithelium consisting only of epithelio-muscle cells to a pseudostratified myoepithelium. The lophophoral coelothelium forms the musculature and blood vessel wall of the brachia and tentacles. The lophophoral blood vessel runs in the extracellular matrix of the septum that separates the large and small canals. In the lophophoral vessel, the upper wall consists of epithelio-muscle cells, whereas the lower wall is formed by peritoneal cells. The lophophoral vessel gives rise to blind branches into each tentacle. The lophophoral wall is highly muscular and contains both longitudinal and transverse muscles. Because the spirolophe lophophore of H. psittacea is supported only by short crura, the coelomic system of the lophophore is assumed to stabilize the lophophore by regulating the hydrostatic pressure of the coelomic fluid. [ABSTRACT FROM AUTHOR]

Objective: Ileal transposition (IT) procedure leads to higher secretion of incretin hormones what is associated with a beneficial metabolic effect. However, IT will also have an influence on the related jejunum and ileum function. The aim of this research was to investigate the morphology of the jejunum and transposed ileum with the use of light and transmission electron microscopy (TEM) in order to determine the local alternations in the intestine resulting from the transposition.Methods: Twenty male, 8-week-old, obese Zucker rats underwent IT and six of them sham surgery. To compare both groups, the transection was made at all corresponding ileum positions among both groups of animals. The ileal anastomoses among the rats of sham procedure were subsequently formed accordingly without IT. Three months following the surgery, the tissue samples of jejunum and ileum were harvested.Results: A significant increase in villus length, a decrease in the crypt depth, and an increased thickness of mucosa-muscularis-serosa (MMS) as well as cellular hyperplasia, with increased mitochondrial density of the transposed ileum segment, were observed among the group of rats which underwent IT comparing to the ones undergoing sham surgery. In rats undergoing IT, microvillus degeneration in jejunum regions was observed.Conclusions: Ileal transposition alters the morphology and ultrastructure of the ileum as well as the jejunum. Given that the microvillus membrane represents an important aspect of the enterocyte functions, a further biochemical and molecular research is necessary in order to assess whether the observed changes are beneficial or not and to explore the phenomenon of gut adaptability after metabolic surgery. [ABSTRACT FROM AUTHOR]

The epidermis of Tarentola mauritanica in the skin regions of back, flank and belly has been described using light and electron microscopy. This animal model was useful to give an insight of the functional pattern involved in pigmentation, cryptism and photosensitivity. Skin from back and flanks, in electron microscopy, shows a high concentration of chromatophores, among those melanophores, xanthophores and iridophores have been reported. Interestingly, in the flank-back transition region electron microscopy reveals the presence of nerve endings. Our contribution adds new knowledge about the skin of this species, and it could be useful to study in deep the mechanism of cryptic colour change in reptiles. [ABSTRACT FROM AUTHOR]

Summary: Ultrastructure of plasma cells in Harderian gland was investigated using the transmission electron microscopy. For this research, we examined the glands of 32 laying hens collected at 1, 7, 20 and 40 days and 4, 6, 8 and 12 months of the birds' ages. The research showed that the stroma of the gland contains a large number of lymphocytes and plasma cells. Most of the plasma cells are mature, but morphologically do not show productive activity. Only some individual plasma cells, situated under the secretory epithelium of primary and secondary ducts, have extremely dilated cisternae of rough endoplasmic reticulum which contain moderately dense, granular material. The morphology of these cells indicates that they are in active stage of immunoglobulin production. Also, we identified plasma cells with two types of Russell bodies. One type of these bodies was small, round or oval, while the other had irregular, angular shape. It was noted that one plasma cell never contains both type of Russell bodies at the same time. These cells were often affected by apoptosis. Among them, in deeper part of the stroma, were situated the small plasmablast cells. [ABSTRACT FROM AUTHOR]

Establishing structure-activity relationships in complex, hierarchically structured nanomaterials, such as fluid catalytic cracking (FCC) catalysts, requires characterization with complementary, correlated analysis techniques. An integrated setup has been developed to perform transmission electron microscopy (TEM) and single-molecule fluorescence (SMF) microscopy on such nanostructured samples. Correlated structure-reactivity information was obtained for 100 nm thin, microtomed sections of a single FCC catalyst particle using this novel SMF-TEM high-resolution combination. High reactivity in a thiophene oligomerization probe reaction correlated well with TEM-derived zeolite locations, while matrix components, such as clay and amorphous binder material, were found not to display activity. Differences in fluorescence intensity were also observed within and between distinct zeolite aggregate domains, indicating that not all zeolite domains are equally active. [ABSTRACT FROM AUTHOR]

To assess serial section block-face scanning electron microscopy (SBFSEM) for retinal pigment epithelium (RPE) ultrastructure, we determined the number and distribution within RPE cell bodies of melanosomes (M), lipofuscin (L), and melanolipofuscin (ML). Eyes of 4 Caucasian donors (16M, 32F, 76F, 84M) with unremarkable maculas were sectioned and imaged using an SEM fitted with an in-chamber automated ultramicrotome. Aligned image stacks were generated by alternately imaging an epoxy resin block face using backscattered electrons, then removing a 125 nm-thick layer. Series of 249-499 sections containing 5–24 nuclei were examined per eye. Trained readers manually assigned boundaries of individual cells and x,y,z locations of M, L, and ML. A Density Recovery Profile was computed in three dimensions for M, L, and ML. The number of granules per RPE cell body in 16M, 32F, 76F, and 84M eyes, respectively, was 465 ± 127 (mean ± SD), 305 ± 92, 79 ± 40, and 333 ± 134 for L; 13 ± 9; 6 ± 7, 131 ± 55, and 184 ± 66 for ML; and 29 ± 19, 24 ± 12, 12 ± 7, and 7 ± 3 for M. Granule types were spatially organized, with M near apical processes. The effective radius, a sphere of decreased probability for granule occurrence, was 1 μm for L, ML, and M combined. In conclusion, SBFEM reveals that adult human RPE has hundreds of L, LF, and M and that granule spacing is regulated by granule size alone. When obtained for a larger sample, this information will enable hypothesis testing about organelle turnover and regulation in health, aging, and disease, and elucidate how RPE-specific signals are generated in clinical optical coherence tomography and autofluorescence imaging. [ABSTRACT FROM AUTHOR]

In the rat model of amyotrophic lateral sclerosis expressing the G93A superoxide dismutase-1 mutation, motor neuron death and rapid paralysis progression are associated with the emergence of a population of aberrant glial cells (AbAs) that proliferate in the degenerating spinal cord. Targeting of AbAs with anti-neoplasic drugs reduced paralysis progression, suggesting a pathogenic potential contribution of these cells accelerating paralysis progression. In the present study, analyze the cellular and ultrastructural features of AbAs following their isolation and establishment in culture during several passages. We found that AbAs exhibit permanent loss of contact inhibition, absence of intermediate filaments and abundance of microtubules, together with an important production of extracellular matrix components. Remarkably, AbAs also exhibited exacerbated ER stress together with a significant abundance of lipid droplets, as well as autophagic and secretory vesicles, all characteristic features of cellular stress and inflammatory activation. Taken together, the present data show AbA cells as a unique aberrant phenotype for a glial cell that might explain their pathogenic and neurotoxic effects. [ABSTRACT FROM AUTHOR]

Routine diagnostic electron microscopy of primary ciliary dyskinesia (PCD) is based on the findings of ultrastructural defects of axonemal components. Assessment of the typical abnormalities can be enhanced by improving the sample preservation status using tannic acid (TA) as additive in the biopsy fixation or processing steps. Another option is the implementation of computer-assisted image analysis tools. Advancements in high-resolution 3D visualization of the axonemal structure have been noted, with great potential for the future diagnosis of inherited cilia disorders. [ABSTRACT FROM AUTHOR]

Most harvestman species are dependent on high humidity levels and amenable temperatures for homeostasis. While they are known to actively choose environments with these conditions, no thermo-/hygroreceptor has yet been identified in harvestmen. Using electron microscopy, we investigated the ultrastructure of two types of hair sensilla of the armored harvestman Heteromitobates discolor (Laniatores, Gonyleptidae): namely the sensillum basiconicum and the hooded sensillum. Both structures occur in small numbers ( sensilla basiconica : 28 units; hooded sensilla: 4 units) and are distributed on the distal parts of the legs. On the distalmost tarsomeres I and II, the receptor cells of paired sensilla basiconica and single hooded sensillum occupy a large volume of the inner tissue, and appear tightly associated. The sensillum basiconicum is innervated by 3-4 dendrites and has a longitudinal slit giving the impression of a shaft with two flaps, resembling a beak. The slit probably allows for evaporation of sensillum lymph. The hooded sensillum is innervated by two bundles of three dendrites each, has two pore-like structures on its tip and displays an unusual reticulate cuticle of the shaft. Details of shaft cuticle, the evidence of evaporation of sensillum lymph, and specific innervation patterns support our hypothesis that sensilla basiconica are thermo- and/or hygroreceptors. Even though the definite function of hooded sensilla remains unclear, its putative receptor modalities are assessed by means of specific ultrastructures. Finally, we discuss with regard to functional ultrastructures as to whether the evaporation system of sensilla basiconica fits mechanisms of hygroreception as known from current literature. [ABSTRACT FROM AUTHOR]

Mucociliary clearance is a main defense mechanism of the respiratory tract, which can be inherently impaired in primary ciliary dyskinesia (PCD) or reversibly altered in secondary ciliary dyskinesia (SCD). Limited diagnostic test availability likely leads to misdiagnosis or underdiagnosis of PCD in animals. This study evaluated the light and transmission electron microscopy (TEM) changes in the respiratory mucosa of 15 dogs with chronic respiratory disease suspected of PCD. Necropsy was performed in 1 case and 2 dogs were used as negative controls. PCD was confirmed in 1 dog, which presented with chronic otitis, bronchopneumonia, hydrocephalus and ultrastructural abnormalities in 84% of the assessed cilia, including absence of dynein arms and microtubular changes. The 14 other cases showed only nonspecific alterations, such as ciliary disorientation, compound cilia, ciliary edema, and axoneme bubbles in a minority of the evaluated cilia and were classified as SCD. Ciliary ultrastructural analysis can confirm a diagnosis of PCD if specific abnormalities exist. TEM remains an important investigational tool in veterinary medicine, as no other specific test for PCD in dogs has been standardized yet. [ABSTRACT FROM AUTHOR]

Monocyte activation is consistently reported in patients with schizophrenia (SZ). We aimed to study the ultrastructure of monocytes and monocyte production of IL-1β in drug-free patients with SZ and controls. Monocytes from young (18-30 y.o.) healthy and SZ men in relapse were studied. Electron microscopy and morphometry were applied to estimate areas of monocytes, volume density (Vv), areas, and number of organelles. The production IL-1β by monocytes was estimated by the ELISA method. Group differences were examined using ANCOVA. Pearson's correlation coefficients were used to examine the effects of possible confounding variables. Correlation analyses were applied to detect the relationships between the parameters of monocytes measured and between the parameters measured and the IL-1β production. Area of nucleolus, Vv and area of mitochondria and lysosomes, and the number of lysosomes were significantly increased in patients as compared to controls. Area of mitochondria was correlated significantly with Vv and area of lysosomes, and the number of lysosomes was significantly correlated with area of monocyte and Vv of vacuoles only in the control group. The production of IL-1β by monocytes was higher in patients than in controls ( p = 0.01) and was correlated with Vv of lysosomes ( r = 0.68, p = 0.04) and area of lysosomes ( r = 0.78, p = 0.013). The data provide new evidence for over activation of monocytes in SZ and disturbed metabolic relationships between lysosomes, mitochondria, and vacuoles. [ABSTRACT FROM AUTHOR]

Amphiura filiformis is a common burrowing brittle star from muddy environments along the European shores. This species emits a blue light at the level of the arm spine tips when mechanically stimulated. Although the putative luciferase of A. filiformis was recently discovered, the ultrastructure of the luminous cells, i.e. the photocytes, remain unknown for this species as well as for most other bioluminescent echinoderms. In this study, we describe the morphology of the arm and spines in the brittle star A. filiformis and compare it to the luciferase expression pattern revealed by immunohistochemistry. Luciferase is expressed at the base of the spine and at the arm tips within well-defined photocyte clusters. Additionally, we investigated the ultrastructure of spine tissues before and after chemical stimulation of light emission in order to identify photocytes and improve our comprehension of the photogenesis phenomenon in brittle stars. Type II granular cells, found in the basal to mid-basal portion of the spine inner tissues and showing ultrastructural modifications during light-emission, are proposed as photocytes. Putative photocytes appear intimately associated with the spine nerve plexus as well as with mucus cells and presumptive pigment cells. Photocytes are characterised by the presence of specific vesicles with reticulated contents in their cytoplasm. Furthermore, the structure of the calcified spine ossicle has been investigated using microCT scanning. [ABSTRACT FROM AUTHOR]

A case of a 47-year-old male with a sacral spine mass was investigated by histology, immunohistochemistry (IHC), and electron microscopy (EM). The light microscopy of the first core biopsy revealed scant cellularity with spindle and round cells with eosinophilic cytoplasm within a fibromyxoid background. Immunostaining with pancytokeratin, cytokeratin 19, and S100 was nonspecific. Another biopsy was attempted to obtain a more definitive diagnosis. Light microscopy of the second core had scant cellular material. However, the tissue was specifically requested for ultrastructural evaluation and revealed features diagnostic of chordoma. After definitive diagnosis, radical resection of the mass was performed. This case illustrates how EM was instrumental in the definitive diagnosis before radical resection in a case that was not clear by hematoxylin and eosin (H&E) and IHC alone. [ABSTRACT FROM PUBLISHER]

The Dufour gland of two Myzinum females was studied with light and electron microscopy, and is formed by a large sac lined with a monolayered secretory epithelium. The epithelium displays a crenellate appearance, which is the result of the peculiar shape of the secretory cells, that have a cupola-like central portion and a more flattened appearance in the contact region with other cells. The ultrastructural organization is indicative for the elaboration of a non-proteinaceous secretion. The gland opens ventrally to the sting base, but does not open through the sting, as does the venom gland duct. The sting itself is dorsally curved, which may be a functional adaptation to facilitate stinging large beetle larvae from above, as these are the common hosts for tiphiid wasps. [ABSTRACT FROM AUTHOR]

Duckweed is considered to be one of the most attractive higher plants to provide the life support requirements of the crew in long-duration space missions. Two species of duckweed, Lemna aequinoctialis and Wolffia globosa , were comparatively studied with focus on the effects of simulated microgravity conditions. A significant enhancement of plant relative growth rate (RGR) was observed under simulated microgravity conditions. The mean RGR of L. aequinoctialis was 32% increased, and W. globosa was 12% increased compared to control. Light and electron microscope analyses showed that the mesophyll cells of duckweed fronds were loosely arranged and many intercellular air spaces enclosed by mesophyll cells were observed in reaction to simulated microgravity, and few starch grains were detected in root tip cells in L. aequinoctialis under simulated microgravity conditions. For L. aequinoctialis , the starch content was significantly increased under simulated microgravity conditions. Thus, the starch content of W. globosa under simulated microgravity conditions was kept stable during all growth periods. This pattern might be associated with the different expression change of the rate-limiting gene APL in regulating starch levels. Taking into consideration of the duckweed growth, ultra-structure and starch content changes, we considered that simulated microgravity conditions do not have a significant adversely affect on the duckweed growth. [ABSTRACT FROM AUTHOR]

Objective: Neuroimaging studies showed abnormalities in frontal white matter (WM) in schizophrenia that were associated with clinical symptoms. Previously, we reported ultrastructural alterations of myelinated fibers and reduction in the numerical density of oligodendrocytes in BA 10 WM in patients with schizophrenia. We aimed to perform a qualitative and morphometric study of the ultrastructure of oligodendrocytes in BA 10 WM in schizophrenia and in normal controls.Methods: The study was performed using electron microscopy and morphometry. Size, volume density (Vv) and the number (N) of organelles of oligodendrocytes were estimated in 21 patients with schizophrenia and 20 normal controls. The data were examined using the Kolmogorov-Smirnov test for normality. Pearson correlation analysis was performed to assess possible correlations between the parameters measured and age, post-mortem interval, neuroleptic treatment and duration of the disease. Comparisons between the schizophrenia patients and controls were performed using ANCOVA tests.Results: We found oligodendrocyte swelling, vacuolation, paucity of ribosomes and mitochondria and accumulation of lipofuscin granules in schizophrenia as compared to controls. Morphometry detected a significant reduction in Vv and N of mitochondria and the increase in Vv and N of lipofuscin granules and vacuoles in oligodendrocytes in the schizophrenic group as compared to controls.Conclusion: Alterations of oligodendrocytes in schizophrenia provide evidence for the disturbance of their energy, lipid and protein metabolism in prefrontal WM. Oligodendrocyte abnormalities might disturb axonal integrity and circuitry and contribute to the pathophysiology of schizophrenia. [ABSTRACT FROM AUTHOR]

Based on light and electron microscopy observations, oogenesis in the cotylean polyclad Prosthiostomum siphunculus was investigated for the first time. The numerous ovarian follicles are dispersed essentially in the dorsal parenchyma. In the follicles, a ventral germinative zone with undifferentiated germs cells of different sizes and a dorsal growth zone with larger growing and abortive oocytes are present. The oogenesis could be subdivided into four stages: (1) Oogonia with a dark nucleus and a dark, ribosome-rich cytoplasm. (2) Early oocyte stage, represented by relatively small cells (10 μm in diameter), a cytoplasm showing some mitochondria and some endoplasmic reticula. (3) Previtellogenic stage, with a decrease of the nucleo-cytoplasmic ratio due to the remarkable increase in ooplasm volume. Immature eggshell globules are observed. (4) Vitellogenic stage, including early vitellogenic ovarian stage, in which a second type of globule (inclusion globule) is formed, and a late vitellogenic uterine stage, in which the inclusion globules are not present anymore. The mature eggshell globules form a peripheral layer under the cell membrane. Eggshell and inclusion globules were analyzed with electron energy loss spectroscopy, electron spectroscopic imaging, protease treatment, and with periodic acid thiocarbohydracide silver proteinate to detect polysaccharides. Chromatoid bodies are present in all four stages. For the first time in a flatworm, we provide evidence that accessory cells, forming a tunica around the ovarian follicles, are epithelial or epithelium-like and likely contribute nutrients for the growth of the oocytes. [ABSTRACT FROM AUTHOR]