CONCLUSIONS: The ultrastructural design and biochemical organization of the significantly thickened outer tissues of the gametophytic stem of Hypnodendron menziesii optimizes load bearing of the stem. Hypnodendron menziesii is a bryoid umbrella moss growing in high humid conditions on the forest floors of New Zealand. The erect gametophyte bears up to eight whorls of branches in succession, spreading across the stem that bears the heavy weight of branches with highly hydrated leaves. Our investigation using a combination of light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and TEM-immunolabeling techniques provided novel information on the structural design and biochemical organization of greatly thickened cell walls of epidermal, hypodermal, and outermost cortical tissues, comparing underlying thin-walled cortical tissues in the gametophytic stem. Probing into the ultrastructure of the cell wall architecture of these target tissues by TEM and SEM revealed the cell walls to display a multilamellar organization, in addition to demonstrating the presence of an electron-dense substance in the cell wall, presumably flavonoids. The pattern of distribution and concentration of rhamnogalacturonan, homogalacturonan, and heteromannan, as determined by immunogold labeling, suggests that it is the combination of structural and molecular design of the cell wall that may optimize the mechanical function of the epidermal, hypodermal, and outer cortical tissues. Statistical relationships between the overall thickness of epidermal, hypodermal, and outer cortical cell walls, the lumen area of cells and the percentage area of cell wall occupied in these tissues at different heights of the stem, and thickness of secondary cell wall layers (L1-L4/5) were explored. The results of these analyses unequivocally support the contribution of outer tissues to the mechanical strength of the resilient stem.

Bacterial extracellular vesicles (BEVs) have emerged as mediators of transkingdom communication with numerous potential biotechnological applications. As such, investigation of BEV\'s protein composition holds promise to uncover new biological mechanisms, such as in microbiome-host communication or pathogen infection. Additionally, bioengineering of BEV protein composition can enhance their therapeutic potential. However, accurate assessment of BEV protein cargo is limited by their nanometer size, which precludes light microscopy imaging, as well as by co-isolation of protein impurities during separation processes. A solution to these challenges is found in immunogold transmission electron microscopy (TEM), which combines antibody-based labeling with direct visualization of BEVs. Several challenges are commonly encountered during immunogold TEM analysis of BEVs, most notably inefficient antibody labeling and poor contrast. Here, we present an optimized protocol for immunogold TEM analysis of BEVs that overcomes such challenges.

Synaptic proteins need to be replaced regularly, to maintain function and to prevent damage. It is unclear whether this process, known as protein turnover, relates to synaptic morphology. To test this, we relied on nanoscale secondary ion mass spectrometry, to detect newly synthesized synaptic components in the brains of young adult (6 mo old) and aged mice (24 mo old), and on transmission electron microscopy, to reveal synapse morphology. Several parameters correlated to turnover, including pre- and postsynaptic size, the number of synaptic vesicles and the presence of a postsynaptic nascent zone. In aged mice, the turnover of all brain compartments was reduced by ∼20%. The turnover rates of the pre- and postsynapses correlated well in aged mice, suggesting that they are subject to common regulatory mechanisms. This correlation was poorer in young adult mice, in line with their higher synaptic dynamics. We conclude that synapse turnover is reflected by synaptic morphology.

UNASSIGNED: High altitude retinopathy (HAR) is a retinal functional disorder caused by inadequate adaptation after exposure to high altitude. However, the cellular and molecular mechanisms underlying retinal dysfunction remain elusive. Retinal ganglion cell (RGC) injury is the most important pathological basis for most retinal and optic nerve diseases. Studies focusing on RGC injury after high-altitude exposure (HAE) are scanty. Therefore, the present study sought to explore both functional and morphological alterations of RGCs after HAE.
UNASSIGNED: A mouse model of acute hypobaric hypoxia was established by mimicking the conditions of a high altitude of 5000 m. After HAE for 2, 4, 6, 10, 24, and 72 hours, the functional and morphological alterations of RGCs were assessed using retinal hematoxylin and eosin (H&E) sections, retinal whole mounts, transmission electron microscopy (TEM), and the photopic negative response (PhNR) of the electroretinogram.
UNASSIGNED: Compared with the control group, the thickness of the ganglion cell layer and retinal nerve fiber layer increased significantly, RGC loss remained significant, and the amplitudes of a-wave, b-wave, and PhNR were significantly reduced after HAE. In addition, RGCs and their axons exhibited an abnormal ultrastructure after HAE, including nuclear membrane abnormalities, uneven distribution of chromatin in the nucleus, decreased cytoplasmic electron density, widening and vacuolization of the gap between axons, loosening and disorder of myelin sheath structure, widening of the gap between myelin sheath and axon membrane, decreased axoplasmic density, unclear microtubule and nerve fiber structure, and abnormal mitochondrial structure (mostly swollen, with widened membrane gaps and reduced cristae and vacuolization).
UNASSIGNED: The study findings confirm that the morphology and function of RGCs are damaged after HAE. These findings lay the foundation for further study of the specific molecular mechanisms of HAR and promote the effective prevention.

High-pressure freezing/freeze substitution has been used to preserve biological samples for ultrastructure study instead of chemical fixation. For most plant samples, the water content is too high and cannot be properly preserved during cryofixation. Additionally, the cell wall is a barrier that prevents the substitution of water with the resin. In this chapter, we will discuss modified high-pressure freezing and subsequent processing protocols based on our routinely used methodology for examining Arabidopsis seeds in transmission electron microscopy and electron tomography.

BACKGROUND: The integrity of the stratum corneum (SC) is crucial for the skin\'s barrier function, protecting against environmental stressors and minimizing transepidermal water loss. Advances in skincare formulations have introduced multilamellar systems designed to emulate the SC\'s lipid composition and organization. This study hypothesizes that the application of a multilamellar cream will significantly impact the SC\'s lipid content and lamellar structure, thereby enhancing the epidermal barrier.
METHODS: A saturated phosphatidylcholine-based multilamellar cream was applied to a cohort of adult subjects with very dry skin. Electron microscopy was utilized to analyse the micro-morphology of the cream and its integration into the lipid-depleted SC. Lipid analysis was conducted to quantify changes in the intercellular lipid matrix.
RESULTS: Transmission-electron microscopy (TEM) imaging demonstrated that the multilamellar cream possesses a structured arrangement comparable to the natural SC architecture. Short-term application revealed a time-dependent restoration of lipid bilayers, while a 14-day regimen showed a marked increase in lipid lamellae density and length within the SC. Lipid analysis indicated a significant increase in total lipid content, with notable enhancements in ceramide and free fatty acid levels, without altering cholesterol levels. Lipid ratio analysis further confirmed the rebalancing of the SC\'s lipid composition.
CONCLUSIONS: The multilamellar cream selectively increased specific lipids critical for barrier function, suggesting an action mechanism that aligns with the skin\'s natural regulatory processes. This selective augmentation indicates the potential of the formulation to not only restore but also enhance the epidermal barrier, with the maintenance of physiological lipid ratios suggesting compatibility with intrinsic repair mechanisms.
CONCLUSIONS: The study confirms that a multilamellar cream can significantly improve the SC\'s lipid composition and structural integrity, indicating enhanced barrier function. They are pivotal for skincare professionals, dermatologists, and product developers, enriching the understanding of multilamellar creams\' benefits and applications in improving epidermal barrier function.
BACKGROUND: l\'intégrité de la couche cornée (SC, stratum corneum) est essentielle pour la fonction de barrière cutanée, protégeant contre les facteurs de stress environnementaux et réduisant au minimum la perte d\'eau transépidermique. Les progrès en matière de formulations pour soins de la peau ont introduit des systèmes multilamellaires conçus pour simuler la composition et l\'organisation lipidique du SC. Cette étude émet l\'hypothèse que l\'application d\'une crème multilamellaire aura un impact significatif sur la teneur en lipides et la structure lamellaire du SC, améliorant ainsi la barrière épidermique. MÉTHODES: Une crème multilamellaire à base de phosphatidylcholine saturée a été appliquée à une cohorte de sujets adultes présentant une peau très sèche. La microscopie électronique a été utilisée pour analyser la micromorphologie de la crème et son intégration dans le SC délipidé. Une analyse lipidique a été réalisée pour quantifier les changements dans la matrice lipidique intercellulaire. RÉSULTATS: l\'imagerie par TEM a démontré que la crème multilamellaire possède un agencement structuré comparable à l\'architecture naturelle du SC. L\'application à court terme a révélé une restauration dépendante du temps des bicouches lipidiques, tandis qu\'un schéma posologique de 14 jours a montré une augmentation marquée de la densité et de la longueur des lamelles lipidiques au sein du SC. L\'analyse lipidique a indiqué une augmentation significative de la teneur lipidique totale, avec des améliorations notables des taux de céramide et d\'acides gras libres, sans altérer les taux de cholestérol. L\'analyse du rapport lipidique a confirmé le rééquilibrage de la composition lipidique du SC.
CONCLUSIONS: la crème multilamellaire a augmenté de manière sélective les lipides spécifiques essentiels à la fonction de barrière, suggérant un mécanisme d\'action qui s\'aligne sur les processus de régulation naturels de la peau. Cette augmentation sélective indique le potentiel de la formulation non seulement à restaurer, mais également à améliorer la barrière épidermique, avec le maintien des rapports lipidiques physiologiques suggérant une compatibilité avec les mécanismes de réparation intrinsèques.
CONCLUSIONS: l\'étude confirme qu\'une crème multilamellaire peut améliorer de manière significative la composition lipidique et l\'intégrité structurelle du SC, ce qui indique une meilleure fonction de barrière. Ils sont essentiels pour les professionnels de la peau, les dermatologues et les développeurs de produits, et enrichissent la compréhension des bénéfices et des applications des crèmes multilamellaires dans l\'amélioration de la fonction de la barrière épidermique.

OBJECTIVE: Ex vivo skin has been used to study various skin conditions from atopic dermatitis to burn injury. The aim of this research is to identify a more effective barrier improvement strategy and to evaluate topical formulations in replenishing the skin. The skin can create new longer chain fatty acids and ceramides (CERs) from topically applied skin natural fatty acid to help renew the skin\'s barrier.
METHODS: An ex vivo skin model damaged by sequential tape stripping of the stratum corneum (SC) was used to investigate the repair of the SC. Confocal laser scanning microscopy was used to assess the SC layers recovered. Ultrastructural analysis was performed using transmission electron microscopy to visualize the lamellar bodies and intercellular lipid lamellae.
RESULTS: The data in this study provide the first direct ex vivo evidence comparing different marketed formulations containing three CERs with those containing fatty acids. Free fatty acid (FFA)-containing formulations, but not CER-containing formulations, directly applied to the damaged skin, showed an increased number of repaired SC layers and this was reflected at the ultrastructural level by an increased intercellular lipid lamellae length and an increased number of lamellar bodies.
CONCLUSIONS: These findings demonstrate that FFA-containing formulations can repair damaged ex vivo skin and point to a repair mechanism in which topically applied palmitic and stearic acids, (which boost lipid levels and elongation) can increase the production and transport of lipids into a repaired SC and thus rebuild an effective skin barrier.
OBJECTIVE: La peau ex vivo a été utilisée pour étudier diverses affections cutanées, allant de la dermatite atopique aux brûlures. L’objectif de cette étude est d’identifier une stratégie d’amélioration de la barrière cutanée plus efficace et d’évaluer les formulations topiques pour reconstituer la peau. La peau peut créer de nouveaux acides gras à chaîne plus longue et des céramides (CER) à partir d’acides gras naturels de la peau appliqués par voie topique pour aider à renouveler la barrière cutanée. MÉTHODES: Un modèle de peau ex vivo endommagé par un décapage séquentiel de la couche cornée a été utilisé pour étudier la réparation de la couche cornée. La microscopie confocale à balayage laser a été utilisée pour évaluer les couches de la couche cornée récupérées. Une analyse ultrastructurale a été réalisée par microscopie électronique à transmission pour visualiser les corps lamellaires et les lamelles lipidiques intercellulaires. RÉSULTATS: Les données de cette étude fournissent les premières preuves directes ex vivo comparant différentes formulations commercialisées contenant trois CER avec celles contenant des acides gras. Les formulations contenant des acides gras libres (AGL), mais pas celles contenant des CER, appliquées directement sur la peau endommagée, ont montré un nombre accru de couches de la couche cornée réparées, ce qui s’est traduit au niveau ultrastructural par une augmentation de la longueur des lamelles lipidiques intercellulaires et une augmentation du nombre de corps lamellaires.
CONCLUSIONS: Ces résultats démontrent que les formulations contenant des AGL peuvent réparer la peau ex vivo endommagée et indiquent un mécanisme de réparation dans lequel les acides palmitique et stéarique appliqués par voie topique (qui stimulent les taux de lipides et leur allongement) peuvent augmenter la production et le transport de lipides dans une couche cornée réparée et ainsi reconstruire une barrière cutanée efficace.

Background and Objectives: Preeclampsia has been linked to an inflammatory response that may be brought on by endothelial cell dysfunction. This paper investigates the pathomechanism of syncytiotrophoblast basement membrane (STBM) damage and Placental Protein 13 (PP13) release, which may have a role in systemic endothelial dysfunction in preeclampsia. Materials and Methods: This comparative cross-sectional study involves 54 preeclampsia patients (27 early-onset preeclampsia and 27 late-onset preeclampsia) and 27 pregnant women with normal blood pressure. An enzyme-linked immunosorbent assay was performed to evaluate maternal blood levels of PP13. Following birth, a portion of the placenta was collected for transmission electron microscope (TEM) and immunohistochemical (IHC) analysis. The data were analyzed using STATA version 15. Results: PP13 expression in the placental syncytiotrophoblast was significantly lower in the early-onset preeclampsia, compared to late-onset preeclampsia and normotensive pregnancy, group (p < 0.001). In contrast, serum PP13 levels were found to be the highest in the early-onset preeclampsia group, although no significant difference were found in mean maternal serum levels of PP13 between the three groups. The decreased PP13 expression in placental syncytiotrophoblast can be attributed to the greater extent of damage in the STBM in early-onset preeclampsia that leads to the release of a larger amount of PP13 into maternal circulation. The hypothesis aligns with the TEM analysis results. Preeclamptic pregnancies showed placental syncytiotrophoblast aponeurosis, whereas normotensive pregnancies did not. Placental lesions and STBM shedding were found to be more pronounced in early-onset preeclampsia compared to late-onset preeclampsia. Conclusions: PP13 and STBM damage may play a role in systemic endothelial dysfunction in preeclampsia.

BACKGROUND: Mitochondria play a crucial role in adapting to fluctuating energy demands, particularly in various heart diseases. This study investigates mitochondrial morphology near intercalated discs in left ventricular (LV) heart tissues, comparing samples from patients with sinus rhythm (SR), atrial fibrillation (AF), dilated cardiomyopathy (DCM), and ischemic cardiomyopathy (ICM).
METHODS: Transmission electron microscopy was used to analyze mitochondria within 0-3.5 μm and 3.5-7 μm of intercalated discs in 9 SR, 10 AF, 9 DCM, and 8 ICM patient samples. Parameters included mean size in µm2 and elongation, count, percental mitochondrial area in the measuring frame, and a conglomeration score.
RESULTS: AF patients exhibited higher counts of small mitochondria in the LV myocardium, resembling SR. DCM and ICM groups had fewer, larger, and often hydropic mitochondria. Accumulation rates and percental mitochondrial area were similar across groups. Significant positive correlations existed between other defects/size and hydropic mitochondria and between count/area and conglomeration score, while negative correlations between count and size/other defects and between hydropic mitochondria and count could be seen as well.
CONCLUSIONS: Mitochondrial parameters in the LV myocardium of AF patients were similar to those of SR patients, while DCM and ICM displayed distinct changes, including a decrease in number, an increase in size, and compromised mitochondrial morphology. Further research is needed to fully elucidate the pathophysiological role of mitochondrial morphology in different heart diseases, providing deeper insights into potential therapeutic targets and interventions.

BACKGROUND: The Diplolepideae are the larger group within the Arthrodontae mosses, characterized by peristomes formed from residual cell walls. It is now understood that these peristomes exhibit diverse hygroscopic movements, playing a crucial role in spore release. However, the exact mechanism behind this movement remains unclear, lacking direct evidence. This study investigated the microscopic and submicroscopic structures of the peristomes in three Diplolepideae species: Hypopterygium fauriei (Besch.), Pylaisia levieri (Müll. Hal.) Arikawa and Regmatodon declinatus (Hook.) Brid. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to reveal the differences in their hygroscopic movement mechanisms.
RESULTS: The three species exhibited distinct responses upon wetting: H. fauriei\'s exostome closed inwards, P. levieri\' opened outwards, and R. declinatus\' elongated significantly. These differences are attributed to the varying microfibril deposition in the exostome layers. Uniform deposition in the inner layer and minimal deposition in the outer layer enabled exostome opening upon wetting and closing when dry. Our findings suggest that the diastole and contraction of fine microfibrils in the exostome plates and ridges are the key drivers of hygroscopic movement.
CONCLUSIONS: This study provides further evidence at both the structural and submicroscopic levels, contributing to the unraveling of the hygroscopic movement mechanism in Diplolepideae peristomes. This enhanced understanding sheds light on the relationship between peristome structure and function.