The elastic fibre system in the veins of the human lower oesophagus

The elastic, elaunin and oxytalan fibres in the tunica mucosa and tela submucosa of veins of the human lower oesophagus were studied in 30 necropsy and biopsy specimens using appropriate histological and ultrastructural methodologies. Elaunin fibres predominate in the veins endowed with muscle cells. Scattered oxytalan and elastic fibres were also observed, the latter being more numerous at the vein periphery. No noteworthy fibre arrangement was encountered in veins lacking muscle cells. Those fibres disposed around the veins were considered to belong to the connective tissue of the tunica mucosa and tela submucosa in which they are embedded. The veins of the lower oesophagus seem to be of low elasticity, which may be related to a blockage mechanism described for the gastro-oesophageal blood stream in cases of portal hypertension.     

Structure and Development of the Notochord ‘Elastica Externa’ and Nearby Components of the Elastic Fibre System of Agnathans

Between 15 days and 3 months in age, the ‘elastica externa’ of the notochord sheath of larval lampreys develops from patches of moderately dense and amorphous material into a thick, continuous and electron-dense layer. In both lampreys and hagfish, this layer stains strongly with Verhoeff's elastic stain and aldehyde fuchsin and is penetrated by collagen fibrils on both its outer and inner boundaries. Peroxidase labelling using an antibody raised against human elastin specifically labels both the notochord ‘elastica externa’ and the elastic fibre system of lampreys. The diameters of the microfibrils (10–13 nm) of the oxytalan, elaunin and elastic fibres of lampreys and hagfish are the same as those of higher vertebrates. The connective tissue immediately dorsal and ventral to the notochord of lampreys contains mainly oxytalan fibres in very young ammocoetes, a combination of oxytalan, elaunin and elastic fibres in older ammocoetes, and predominantly elastic fibres in adult lampreys. While the region of the endomeninx at the base of the spinal cord contains almost exclusively oxytalan fibres in young ammocoetes, it also possesses numerous elastic fibres in adult lampreys. These findings indicate that, as in higher vertebrates, the elastic fibres of lampreys develop from oxytalan fibres via elaunin fibres.     

Distribution and organization of the elastic system fibres in healthy human gingiva

Summary The ultrastructural distribution and organization of the elastic system fibres, i.e. oxytalan, elaunin and elastic fibres, were studied by transmission electron microscopy and by an immunohistochemical method for the detection of elastin in healthy human gingiva. The morphological distribution of these fibres was characterized by the presence of oxytalan, elaunin and elastic fibres, respectively, in the upper, medium, and deep layers of gingival connective tissue. Anti-elastin antibody reacted with microfibrils and amorphous material of the elastic system fibres throughout the gingival connective tissue. These findings were interpreted as indicating that the microfibrils were associated with small amounts of elastin at their surface.     

STRUCTURAL BIOLOGY OF THE FIBRES OF THE COLLAGENOUS AND ELASTIC SYSTEMS

The different types of fibres of the collagenous and elastic systems can be demonstrated specifically in tissue sections by comparing the typical ultrastructural picture of each of the fibre types with studies using selective staining techniques for light microscopy. A practicalmodus operandi, which includes the recommended staining procedures and interpretation of the results, is presented. Micrographs and tables are provided to summarize the differential procedures. Reticulin fibres display a distinct argyrophilia when studied by means of silver impregnation techniques, and show up as a thin meshwork of weakly birefringent, greenish fibres when examined with the aid of the Picrosirius-polarization method. In addition, electron-microscopic studies showed that reticulin fibres are composed of a small number of thin collagen fibrils, contrasting with the very many thicker fibrils that could be localized ultrastructurally to the sites where non-argyrophilic, coarse collagen fibres had been characterized by the histochemical methods used. The three different fibre types of the elastic system belong to a continuous series: oxytalan—elaunin—elastic (all of the fibre types comprising collections of microfibrils with, in the given sequence, increasing amounts of elastin). The three distinct types of elastic system fibres have different staining characteristics and ultrastructural patterns. Ultrastructurally, a characteristic elastic fibre consists of two morphologically different components: a centrally located solid cylinder of amorphous and homogeneous elastin surrounded by tubular microfibrils. An oxytalan fibre is composed of a bundle of microfibrils, identical to the elastic fibre microfibrils, without amorphous material. In elaunin fibres, dispersed amorphous material (elastin) is intermingled among the microfibrils.     

Histochemistry of elastic and related fibres in the human eye in health and disease

Summary Although the presence of mature elastic fibres in the sclera, trabecular meshwork and Bruch's membrane of the human eye has been recognized for many years, it is only latterly that the existence of the elastic-related fibres oxytalan and elaunin has been appreciated. The microfibrillar component of elastic, oxytalan, which is present in several ocular structures in infancy, can either mature to fully-developed elastic tissue or, as in the cornea, disappear in subsequent years. Deposition of elastic fibres, particularly the incomplete forms, can occur in the post-developmental period in a variety of disease states but the stimulus and functional significance in most situations is obscure. The evidence suggests, however, that the capacity to form elastic-related tissue is not confined to any one cell type.     

Oxytalan fibre organization in marsupial mandibular periodontal tissues

The arrangement and distribution of oxytalan fibers in Australian marsupials has not previously been reported. Periodontal tissues of wombat, wallaby, possum, and marsupial mouse were examined to ascertain oxytalan fibre organization. Despite adaptation of the marsupial masticatory apparatus to different diets the oxytalan fibre organization in the periodontal ligament shows a basic pattern which corresponds with that reported in other animals. The oxytalan system forms a continuous meshwork of fine, branching fibres which completely invests each tooth root and connects adjacent teeth. Thick ribbon-like apico-occlusally orientated oxytalan fibres, thought to form by the coalescence of thinner fibres, are restricted to the periodontal ligament. The oxytalan fibres are embedded in cementum and attached to blood vessels in the periodontal ligament. Oxytalan fibres do not insert into alveolar bone. Histological evidence indicates functional remodelling of the oxytalan fibre system in continuously erupting teeth.     

Improved visualization of elastic and pre-elastic fibres with procyanidolic oligomers in the gingiva

For ultra-structural studies, the staining methods available for histological detection of elastic and pre-elastic fibres are not entirely selective. A reliable, simple and cheap method is described after using procyanidolic (flavane-3, 4-diol) oligomers. Elastin and elastic fibres appear intensely contrasted and oxytalan fibres are found to possess a small amount of amorphous component containing densely stained particles.     

The staining of elastic fibres with Direct Blue 152. A general hypothesis for the staining of elastic fibres

Summary Elastic fibres may be stained by a number of dyes, e.g. Direct Blue 1 (C.I. 24410), Direct Blue 10 (C.I. 24340), Direct Blue 15 (C.I. 24400), Direct Blue 152 (C.I. 24366) and Direct Violet 37 (C.I. 24370). A convenient method using Direct Blue 152 has been developed which is specific for elastic fibres. The method is simple and allows the demonstration of other connective tissue fibres. Staining of elastic fibres is unimpaired by numerous blocking procedures or by changes in dyebath pH. These properties are shared by several standard elastic fibre stains.As the Direct dyes and several of the standard elastic fibre stains possess numerous aromatic rings a wide range of dyes containing varying numbers of aromatic rings were examined for ability to stain elastic fibres. No association was observed between the ability to stain elastic fibres and dye class, formal charge or the presence of hydrogen bonding groups. Staining was, however, definitely associated with the presence in the dye molecule of 5 or more aromatic rings. This suggested that van der Waals forces of attraction may be responsible for elastic fibre staining both by Direct dyes and the standard elastic fibre stains. Staining of elastic fibres as a side-effect in many procedures is similarly explicable.     

Fluorescence microscopical visualization of elastic fibres using basic fuchsin

Summary We show that fluorescence microscopy after staining of tissue sections with basic fuchsin (BF) can be used successfully for the demonstration of elastic fibres. Using double staining with BF and antibodies reacting with microfibrils of elastic fibres (anti-SAP) we showed that BF reacts with the elastin core of elastic fibres and the elastin poor terminal branches of the subepidermal elastic fibre system. Small amounts of bound BF were easily seen by fluorescence microscopy (FL) but not by ordinary light microscopy. Both frozen sections and sections of paraffin embedded tissues could be stained. The BF-FL staining procedure is simple to perform and, due to its selectivity, it may be useful for detecting elastic fibres in various tissues at the light microscopical level.     

Fluorescence microscopical visualization of elastic fibres using basic fuchsin

We show that fluorescence microscopy after staining of tissue sections with basic fuchsin (BF) can be used successfully for the demonstration of elastic fibres. Using double staining with BF and antibodies reacting with microfibrils of elastic fibres (anti-SAP) we showed that BF reacts with the elastin core of elastic fibres and the elastin poor terminal branches of the subepidermal elastic fibre system. Small amounts of bound BF were easily seen by fluorescence microscopy (FL) but not by ordinary light microscopy. Both frozen sections and sections of paraffin embedded tissues could be stained. The BF-FL staining procedure is simple to perform and, due to its selectivity, it may be useful for detecting elastic fibres in various tissues at the light microscopical level.     

Subepithelial elastic system fibers of oblique mucosal folds in the rat proximal colon.

The proximal colon of the rat is characterized by a 'herring bone' pattern of oblique mucosal folds (OMF) which are arranged in a parallel array. By light and electron microscopy the OMF exhibited rich subepithelial elastic system fibers which bound the epithelial basement membrane and the smooth muscle cells of the lamina propria together. The elastic system fibers usually consist of elastic, elaunin and oxytalan fibers. However, the subepithelial elastic system fibers of the OMF were composed of relatively thin elastic fibers with a few microfibrils, and elaunin and oxytalan fibers which were almost indiscernible. Areas other than the OMF were quite poor in subepithelial elastic system fibers. The interpositions between each of the OMF were composed of typical components: elastic, elaunin and oxytalan fibers. The composition of the subepithelial elastic system fibers of the OMF does not correspond to that of any other organs previously reported. The present study suggests that the OMF of the rat proximal colon might be equipped in such a way to resist to distension or compression.     

Occurrence of "elastic" fibres in the invertebrates

The connective tissues of a wide range of invertebrates have been investigated using a potassium permanganate/spirit blue staining technique. The method demonstrates fibres which are distinct from collagen, vertebrate elastic fibres, and reticular fibres. The fibres are variously associated with subepidermal collagen, muscles, basement membrances, the walls of blood vessels and the sheaths around nerve cords; the method also gives a positive reaction with the arborescent mesogloeal fibres of medusoid coelenterates. Their electron microscope appearance is distinctive and they exhibit a physical elasticity. Chemical tests indicate that following pretreatment with acidified potassium permanganate they show many, although not all, of the properties of vertebrate "elastin". It is concluded that they should be regarded as a special category of "elastic" fibre.     

Simulation and study of the behaviour of the transversalis fascia in protecting against the genesis of inguinal hernias

Simulating the muscular system has many applications in biomechanics, biomedicine and the study of movement in general. We are interested in studying the genesis of a very common pathology: human inguinal hernia. We study the effects that some biomechanical parameters have on the dynamic simulation of the region, and their involvement in the genesis of inguinal hernias. We use the finite element method (FEM) and current models for the muscular contraction to determine the deformed fascia transversalis for the estimation of the maximum strain. We analysed the effect of muscular tissue density, Young's modulus, Poisson's coefficient and calcium concentration in the genesis of human inguinal hernia. The results are the estimated maximum strain in our simulations, has a close correlation with experimental data and the accepted commonly models by the medical community. Our model is the first study of the effect of various biological parameters with repercussions on the genesis of the inguinal hernias.     

Immunohistochemical characterization of elastic system fibers in rat molar periodontal ligament.

Among elastic system fibers, oxytalan fibers are known as a ubiquitous component of the periodontal ligament, but the localization and role of elastin-containing fibers, i.e., elastic and elaunin fibers, has yet to be clarified. In this study, we immunohistochemically investigated the localization of elastin and fibrillin, major proteins of elastin-containing fibers in the periodontal ligament of rat lower first molars. At the light microscope level, distribution of elastin-positive fibers was not uniform but often concentrated in the vicinity of blood vessels in the apical region of the ligament. In contrast, fibrillin-positive fibers were more widely distributed throughout the ligament, and the pattern of their distribution was comparable to the reported distribution of oxytalan fibers. At the ultrastructural level, assemblies or bundles of abundant fibrillin-containing microfibrils were intermingled with a small amount of elastin. This observation indicated that elastin-positive fibers observed under the light microscope were elaunin fibers. No mature elastic fibers, however, were found in the ligament. These results show that the major components of elastic system fibers in the periodontal ligament of the rat mandibular first molar were oxytalan and elaunin fibers, suggesting that the elastic system fibers play a role in the mechanical protection of the vascular system.     

Peptide stimulation of phagocytosis in Amoeba proteus

Summary Normal articular cartilages from the weightbearing areas of the femoral condyles of the knee joints of 11 patients (3–20 years old) and of 35 Schwarzkopf sheep (3 months to 2 years old) were studied using the electron microscope. The study has shown that the matrix of normal articular cartilage is not only composed of collagen fibrils and proteoglycans, but also contains two types of elastic system fibres. Small elastic fibres can be identified in the superficial and lower radiate zones of cartilage of man and sheep. Similar to elastic fibres in other tissues, they consist of a central amorphous core and are surrounded by aggregates of 10 nm microfibrils. Another type of elastic system fibres, oxytalan fibres, are found in the intermediate and upper radiate zones of the articular cartilage.     

Evaluation of the flexural strength and elastic modulus of resins used for temporary restorations reinforced with particulate glass fibre

doi: 10.1111/j.1741‐2358.2010.00410.x
Evaluation of the flexural strength and elastic modulus of resins used for temporary restorations reinforced with particulate glass fibre Objective: The flexural strength and the elastic modulus of acrylic resins, Dencor, Duralay and Trim Plus II, were evaluated with and without the addition of silanised glass fibre. Materials and methods: To evaluate the flexural strength and elastic modulus, 60 test specimens were fabricated with the addition of 10% ground silanised glass fibres for the experimental group, and 60 without the incorporation of fibres, for the control group, with 20 test specimens being made of each commercial brand of resin (Dencor, Duralay and Trim Plus II) for the control group and experimental group. After the test specimens had been completed, the flexural strength and elastic modulus tests were performed in a universal testing device, using the three‐point bending test. For the specimens without fibres the One‐Way Analysis of Variance and the complementary Tukey test were used, and for those with fibres it was not normal, so that the non‐parametric Mann‐Whitney test was applied. Results: For the flexural strength test, there was no statistical difference (p > 0.05) between each commercial brand of resin without fibres [Duralay 84.32(±8.54), Trim plus 85.39(±6.74), Dencor 96.70(±6.52)] and with fibres (Duralay 87.18, Trim plus 88.33, Dencor 98.10). However, for the elastic modulus, there was statistical difference (p > 0.01) between each commercial brand of resin without fibres [Duralay 2380.64 (±168.60), Trim plus 2740.37(±311.74), Dencor 2595.42(±261.22)] and with fibres (Duralay 3750.42, Trim plus 3188.80, Dencor 3400.75). Conclusion: The result showed that the incorporation of fibre did not interfere in the flexural strength values, but it increased the values for the elastic modulus.     

Biomolecular analysis of elastic fibre molecules

Elastic fibres are macromolecular extracellular matrix assemblies that endow dynamic connective tissues such as arteries, lungs and skin with the property of elastic recoil. Here, we describe how we have purified elastic fibre molecules and then analysed them using a range of biochemical and biomolecular approaches. Such approaches have provided powerful insights into the complex hierarchical processes of extracellular matrix assembly. We outline molecular interaction and kinetics assays using Biacore, biophysical approaches such as multi-angle laser light scattering and analytical ultracentrifugation which provide information on molecular and macromolecular shape and mass in solution, the visualisation of molecules and assemblies using microscopy approaches such as atomic force microscopy and environmental scanning electron microscopy, and compositional analysis of macromolecular complexes using mass spectrometry. Data from these in vitro analytical approaches can be combined to develop powerful new models of elastic fibre assembly.     

The effect of agarose and dexamethasone on the nature and production of extracellular matrix components by elastic cartilage chondrocytes

Chondrocytes isolated enzymatically from rabbit ear cartilage, were cultivated in vitro in the presence of 2% agarose or 0.1 mumol/l dexamethasone. Freshly-isolated chondrocytes suspended in either Eagle's medium or 2% agarose were auto-transplanted intramuscularly. Samples were then examined by light microscopy and transmission electron microscopy. The cells cultivated in vitro rapidly formed confluent multiple overlapping layers filled with a loose matrix consisting of single collagen fibres, proteoglycans and scarce elastic fibres. The number and maturity of the elastic fibres increased substantially after dexamethasone was added. The chondrocytes in intramuscular transplants produced a larger amount of intercellular matrix with many elastic fibres than those cultured in vitro. Addition of agarose to in vitro and in vivo systems selectively suppressed the elastin production but did not diminish the production of elastic fibre microfibrils and other matrix components. This made cultures and transplants of elastic chondrocytes resemble rather hyaline cartilage than the original tissue. It seems that the lack of elastin in the matrix does not result simply from inhibition of elastin secretion or increased elastolysis. It may be related to a reversible change of genetic expression of elastic cartilage chondrocytes under the influence of agarose.     

Thermodynamics of Orcein staining of elastic fibres

Synopsis Elastic fibres in histological sections have only a slightly higher affinity (than chromatin or cartilage matrix) for unpurified Orcein in acidified 70% ethanol, but the staining of elastic fibres is more exothermic (the heat of staining being in good agreement with publishedin vitro measurements), has a considerably higher activation energy, and is probably accompanied by a greater decrease in entropy. Experiments with purified dye fractions, and unpurified dye in 10% ethanol, were inconclusive, as it was not possible to prove unequivocally that equilibrium between dyebath and substrate had been achieved under these conditions.The results are consistent with the selectivity of orcein for elastic fibres under practical conditions being due to (a) the presence in elastic fibres of a relatively large number of dye-binding sites per unit volume, which probably bind by some non-ionic mechanism, (b) the relatively non-polar nature of elastic fibres, which repel cationic dye particles less than do tissue components that at low pH carry a positive charge, and (c) the low permeability of elastic fibres, so that dyeing, once achieved, is relatively resistant to alcoholic extraction. An alcoholic solvent for the dye enables strong solutions, and hence short staining times, to be used.