• arteries
• blood vessels
• dissection
• sloths
• thermoregulation

• Animals
• Sloths/physiology
• Kidney
• Arteries

• black agouti
• fetuses
• morphology
• urogenital

• Male
• Animals
• Dasyproctidae
• Sex Differentiation
• Penis/anatomy & histology
• Urethra
• Vas Deferens
• Cuniculidae

• SEM
• Shamo chicken
• collagen
• skin

• Cellular cementum
• Contact microradiography
• Incremental lines
• Scanning electron microscopy

Lymph nodes (LNs) comprise two main structural elements: fibroblastic reticular cells that form dedicated niches for immune cell interaction and capsular fibroblasts that build a shell around the organ. Immunological challenge causes LNs to increase more than tenfold in size within a few days. Here, we characterized the biomechanics of LN swelling on the cellular and organ scale. We identified lymphocyte trapping by influx and proliferation as drivers of an outward pressure force, causing fibroblastic reticular cells of the T-zone (TRCs) and their associated conduits to stretch. After an initial phase of relaxation, TRCs sensed the resulting strain through cell matrix adhesions, which coordinated local growth and remodeling of the stromal network. While the expanded TRC network readopted its typical configuration, a massive fibrotic reaction of the organ capsule set in and countered further organ expansion. Thus, different fibroblast populations mechanically control LN swelling in a multitier fashion.

Sixt and colleagues show that different fibroblast populations in the lymph node mechanically control its swelling in a multitier fashion.

Scanning electron microscopy (SEM) has contributed to elucidating the ultrastructure of bio-specimens in three dimensions. SEM imagery detects several kinds of signals, of which secondary electrons (SEs) and backscattered electrons (BSEs) are the main electrons used in biological and biomedical research. SE and BSE signals provide a three-dimensional (3D) surface topography and information on the composition of specimens, respectively. Among the various sample preparation techniques for SE-mode SEM, the osmium maceration method is the only approach for examining the subcellular structure that does not require any reconstruction processes. The 3D ultrastructure of organelles, such as the Golgi apparatus, mitochondria, and endoplasmic reticulum has been uncovered using high-resolution SEM of osmium-macerated tissues. Recent instrumental advances in scanning electron microscopes have broadened the applications of SEM for examining bio-specimens and enabled imaging of resin-embedded tissue blocks and sections using BSE-mode SEM under low-accelerating voltages; such techniques are fundamental to the 3D-SEM methods that are now known as focused ion-beam SEM, serial block-face SEM, and array tomography (i.e., serial section SEM). This technical breakthrough has allowed us to establish an innovative BSE imaging technique called section-face imaging to acquire ultrathin information from resin-embedded tissue sections. In contrast, serial section SEM is a modern 3D imaging technique for creating 3D surface rendering models of cells and organelles from tomographic BSE images of consecutive ultrathin sections embedded in resin. In this article, we introduce our related SEM techniques that use SE and BSE signals, such as the osmium maceration method, semithin section SEM (section-face imaging of resin-embedded semithin sections), section-face imaging for correlative light and SEM, and serial section SEM, to summarize their applications to neural structure and discuss the future possibilities and directions for these methods.

• 3D
• CLEM
• CLSEM
• SEM
• osmium maceration method
• section-face imaging
• semithin section SEM
• serial section SEM

• connective tissue papillae
• hard palate
• palatine mucosa
• red fox
• soft palate
• three-dimensional

• Nile fox
• connective tissue core
• lingual papillae
• three-dimensional
• tongue

• Animal model
• Extracellular matrix
• Female Dogs
• Mammary gland
• Pathology

• Biomechanics
• Collagen fibers
• Connective tissue
• Micro-computed tomography
• Microanatomy
• Tendon-bone insertion

• Osteoglossomorpha
• air-blood barrier
• autocentrum
• eosinophils
• pneumocytes

• Xenarthra
• digestive anatomy
• digestive histology
• stomach

• Dentifrices
• Dentin
• Dentin permeability
• Fluorides
• Phosphates

The mechanism underlying tissue fusion mediated by laser irradiation remains unclear. We clarify the mechanisms underlying laser-mediated tissue fusion using a novel model. Microscopic examinations of morphological changes within the adventitia of a bovine carotid artery and a collagen sheet prepared from bovine dermis showed collagen fibril bundle loosening and collagen fibre swelling following heating at 46 °C. An incised bovine carotid artery covered with a collagen sheet to which pressure and laser heat of 40 °C–52 °C were applied created a structure that was pressure resistant to >300 mmHg. Microscopic analyses of the irradiation site showed collagen fibril interdigitation. Hence, low-temperature laser-mediated tissue fusion causes collagen fibril bundles to loosen and swell, and crimping causes the fibres to intertwine. As the temperature declines, the loosened and swollen fibrils and fibres tighten, and collagen fibre interdigitation is completed. This technology could be applied to fuse tissues during surgery.

• Extracellular matrix
• Matrix biology
• Placenta
• Tissue engineering

Collagen is the main structural element of connective tissues, and its favorable properties make it an ideal biomaterial for regenerative medicine. In dental medicine, collagen barrier membranes fabricated from naturally occurring tissues are used for guided bone regeneration. Since the morphological characteristics of collagen membranes play a crucial role in their mechanical properties and affect the cellular behavior at the defect site, in-depth knowledge of the structure is key. As a base for the development of novel collagen membranes, an extensive morphological analysis of four porcine membranes, including centrum tendineum, pericardium, plica venae cavae and small intestinal submucosa, was performed. Native membranes were analyzed in terms of their thickness. Second harmonic generation and two-photon excitation microscopy of the native membranes showed the 3D architecture of the collagen and elastic fibers, as well as a volumetric index of these two membrane components. The surface morphology, fiber arrangement, collagen fibril diameter and D-periodicity of decellularized membranes were investigated by scanning electron microscopy. All the membrane types showed significant differences in thickness. In general, undulating collagen fibers were arranged in stacked layers, which were parallel to the membrane surface. Multiphoton microscopy revealed a conspicuous superficial elastic fiber network, while the elastin content in deeper layers varied. The elastin/collagen volumetric index was very similar in the investigated membranes and indicated that the collagen content was clearly higher than the elastin content. The surface of both the pericardium and plica venae cavae and the cranial surface of the centrum tendineum revealed a smooth, tightly arranged and crumpled morphology. On the caudal face of the centrum tendineum, a compact collagen arrangement was interrupted by clusters of circular discontinuities. In contrast, both surfaces of the small intestinal submucosa were fibrous, fuzzy and irregular. All the membranes consisted of largely uniform fibrils displaying the characteristic D-banding. This study reveals similarities and relevant differences among the investigated porcine membranes, suggesting that each membrane represents a unique biomaterial suitable for specific applications.

• Animals
• Biocompatible Materials/chemistry
• Collagen/chemistry
• Elastin/chemistry
• Membranes, Artificial
• Optical Imaging
• Swine

• Calcaneus
• collagen fiber
• extracellular matrix
• micro-computed tomography
• propagation-based phase-contrast X-ray imaging
• soft tissue
• tendon-bone insertion

• Calcium phosphates
• Collagen
• Energy-dispersive X-ray spectroscopy
• Fluorides
• Nanoparticles
• X-ray microtomography

• K-value
• extracellular matrix (ECM)
• flesh quality
• horse mackerel
• ice crystal
• scanning electron microscope (SEM)

• Antigen retrieval
• Collagen
• Extracellular matrix
• Immunohistochemistry
• Laminin
• Mouse
• Pancreas
• Pig
• Proteomics
• Scanning electron microscopy

• Aging
• Collagen fibers
• Elastic fibers
• Ileocecal junction
• Rats

The aim of the present study was to describe the tridimensional morphological characteristics of the lingual papillae and their connective tissue cores (CTCs) in Sprague Dawley rats. Four types of papillae were reported on the dorsal surface. Filiform papillae were distributed on the tongue surface and after epithelial maceration a conic and multifilamentary shape of the CTCs was revealed. Fungiform papillae were reported on the rostral and middle regions covered by a squamous epithelium. After the removal of the epithelium, the shape of a volcano with the taste orifice at its top was noted. Foliate papillae were composed of five pairs of epithelial folds situated on the lateral-caudal margin of the tongue. After the removal of the epithelium, they were shown to be limited by thin laminar projections. The vallate papilla with an oval shape was present in the caudal region and delimited by an incomplete groove. The morphological characteristics of the lingual papillae of Sprague Dowley rats, three-dimensional SEM images, and the types of papillae on the dorsal surface were similar to those reported previously in other rodent mammals. The maceration technique revealed the details of extracellular matrix with varied shapes form of connective tissue cores.

• Animals
• Cell Line, Tumor
• Erythrocytes/physiology
• Humans
• Mice
• Micromanipulation/instrumentation
• Micromanipulation/methods
• Microscopy, Electron, Scanning/methods
• Models, Biological
• Particle Size
• Pollen/physiology

• extracellular matrix
• fibroblasts
• fibrosis
• myocardial infarction
• neuregulin

Chondroadherin (CHAD), a class IV small leucine rich proteoglycan/protein (SLRP), was hypothesized to play important roles in regulating chondrocyte signaling and cartilage homeostasis. However, its roles in cartilage development and function are not well understood, and no major osteoarthritis-like phenotype was found in the murine model with CHAD genetically deleted (CHAD^−/−). In this study, we used atomic force microscopy (AFM)-based nanoindentation to quantify the effects of CHAD deletion on changes in the biomechanical function of murine cartilage. In comparison to wild-type (WT) mice, CHAD-deletion resulted in a significant≈70–80% reduction in the indentation modulus, E_ind, of the superficial zone knee cartilage of 11 weeks, 4 months and 1 year old animals. This mechanical phenotype correlates well with observed increases in the heterogeneity collagen fibril diameters in the surface zone. The results suggest that CHAD mainly plays a major role in regulating the formation of the collagen fibrillar network during the early skeletal development. In contrast, CHAD-deletion had no appreciable effects on the indentation mechanics of middle/deep zone cartilage, likely due to the dominating role of aggrecan in the middle/deep zone. The presence of significant rate dependence of the indentation stiffness in both WT and CHAD^−/− knee cartilage suggested the importance of both fluid flow induced poroelasticity and intrinsic viscoelasticity in murine cartilage biomechanical properties. Furthermore, the marked differences in the nanomechanical behavior of WT versus CHAD^−/− cartilage contrasted sharply with the relative absence of overt differences in histological appearance. These observations highlight the sensitivity of nanomechanical tools in evaluating structural and mechanical phenotypes in transgenic mice.

• Cartilage
• Chondroadherin
• Collagen
• Murine model
• Nanoindentation

In this study, we investigated the molecular adhesion between the major constituents of cartilage extracellular matrix, namely, the highly negatively charged proteoglycan aggrecan and the type II/IX/XI fibrillar collagen network, in simulated physiological conditions. Colloidal force spectroscopy was applied to measure the maximum adhesion force and total adhesion energy between aggrecan end-attached spherical tips (end radius R ≈ 2.5 μm) and trypsin-treated cartilage disks with undamaged collagen networks. Studies were carried out in various aqueous solutions to reveal the physical factors that govern aggrecan–collagen adhesion. Increasing both ionic strength and [Ca²⁺] significantly increased adhesion, highlighting the importance of electrostatic repulsion and Ca²⁺-mediated ion bridging effects. In addition, we probed how partial enzymatic degradation of the collagen network, which simulates osteoarthritic conditions, affects the aggrecan–collagen interactions. Interestingly, we found a significant increase in aggrecan–collagen adhesion even when there were no detectable changes at the macro- or microscales. It is hypothesized that the aggrecan–collagen adhesion, together with aggrecan–aggrecan self-adhesion, works synergistically to determine the local molecular deformability and energy dissipation of the cartilage matrix, in turn, affecting its macroscopic tissue properties.

• lymph node
• lymphangiogenesis
• lymphatic vessel
• lymphedema
• metastasis

• tissue dissociation
• collagenase
• islet isolation
• protease
• biochemical characterization
• type 1 diabetes

• Clostridium histolyticum/enzymology
• Clostridium histolyticum/genetics
• Endopeptidases/metabolism
• Endopeptidases/pharmacology
• Enzymes/metabolism
• Enzymes/pharmacology
• Enzymes/standards
• Histological Techniques/methods
• Histological Techniques/standards
• Humans
• In Vitro Techniques
• Islets of Langerhans/anatomy & histology
• Islets of Langerhans/drug effects
• Islets of Langerhans Transplantation/methods
• Islets of Langerhans Transplantation/standards
• Microbial Collagenase/genetics
• Microbial Collagenase/metabolism
• Microbial Collagenase/pharmacology
• Practice Guidelines as Topic/standards
• United States
• United States Food and Drug Administration

• R43 DK070402-01A1 NIDDK NIH HHS
• R43DK070402 NIDDK NIH HHS
• R43 DK070402 NIDDK NIH HHS
• R43 DK079413 NIDDK NIH HHS
• R43DK079413 NIDDK NIH HHS
• R43DK065467 NIDDK NIH HHS
• R43 DK079413-01 NIDDK NIH HHS
• R44 DK065467-04 NIDDK NIH HHS
• R43 DK065467 NIDDK NIH HHS
• R44DK065467 NIDDK NIH HHS
• R44 DK065467 NIDDK NIH HHS

• air and blood capillaries
• bird
• collagen fibers
• lung
• parabronchus
• tensegrity

• Animals
• Bronchi/anatomy & histology
• Bronchi/physiology
• Capillaries/anatomy & histology
• Chickens/anatomy & histology
• Collagen/analysis
• Elastic Tissue/anatomy & histology
• Lung/blood supply
• Lung/ultrastructure
• Microscopy, Electron
• Muscle, Smooth/anatomy & histology