Orientation Of Elastic Fibers Research Articles

The ultrastructural organization of elastic fibers at the interface of the nucleus and annulus of the intervertebral disk

There has been no study to describe the ultrastructural organization of elastic fibers at the interface of the nucleus pulposus and annulus fibrosus of the intervertebral disk (IVD), a region called the transition zone (TZ). A previously developed digestion technique was optimized to eliminate cells and non-elastin ECM components except for the elastic fibers from the anterolateral (AL) and posterolateral (PL) regions of the TZ in ovine IVDs. Not previously reported, the current study identified a complex elastic fiber network across the TZ for both AL and PL regions. In the AL region, this network consisted of major thick elastic fibers (≈ 1 µm) that were interconnected with delicate (< 200 nm) elastic fibers. While the same ultrastructural organization was observed in the PL region, interestingly the size of the elastic fibers was smaller (< 100 nm) compared to those that were located in the AL region. Quantitative analysis of the elastic fibers revealed significant differences in the size (p < 0.001) and the orientation of elastic fibers (p = 0.001) between the AL and PL regions, with a higher orientation and larger size of elastic fibers observed in the AL region. The gradual elimination of cells and non-elastin extracellular matrix components identified that elastic fibers in the TZ region in combination with the extracellular matrix created a honeycomb structure that was more compact at the AF interface compared to that located close to the NP. Three different symmetrically organized angles of rotation (0⁰ and ±90⁰) were detected for the honeycomb structure at both interfaces, and the structure was significantly orientated at the TZ-AF compared to the TZ-NP interface (p = 0.003).

The ultra-structural organization of the elastic network in the intra- and inter-lamellar matrix of the intervertebral disc.

Visualization of the intra-lamellar matrix under high magnification revealed a dense network of elastic fibers that has not been previously described. The present study used extracellular matrix partial digestion to address significant gaps in understanding of disc microstructure and will contribute to multidisciplinary ultrastructure-function studies.

Pathogenesis of Ossification of Ligamentum Flavum

Introduction Ossification of ligamentum flavum (OLF) is a rare disorder. The present study aims at histopathological analysis of OLF with special emphasis on the alterations in the elastin fibers, collagen, matrix, cellularity, chodrocyte proliferation, and osteoid metaplasia. Materials and Methods The study involves histopathologic examination of surgically harvested ligamentum flavum (LF) specimens from 10 OLF, 5 with degenerative spinal stenosis and 5 normal LF as controls. The specimens were studied with hematoxylin and eosin, Verhoff van Gieson, toluidine blue, Masons trichrome, and Alcian blue. All specimens were analyzed qualitatively for (1) elastic fiber orientation, integrity, and loss, (2) collagen bundles,(3) fibrosis,(4) chondroid metaplasia,(5) chondrocyte proliferation, and (6) Osteoid metaplasia. The quantitative analysis was done using SCION image analysis software. Results All the 10 OLF specimens showed extensive loss of elastic fibers associated with cartilage matrix formation. There were many areas of irregularly oriented elastic fibers, areas of ossification and in between there was a transitional area of cartilage matrix with chondrocytes progressing toward ossification. Elastic fiber occupying ratio was 60.96, 40.25, and 22.66%; number of chondrocytes per mm2 was 37.56, 93.35, and 117.68; area of chondroid matrix (%) was 11.34, 32.37, and 73.56, respectively, and the area of osteoid matrix (%) was 0, 9.37, and 33.43 respectively for normal controls, degenerative group, and OLF group. The areas of cartilage matrix were more on the dorsal side compared with the dural side of LF. In contrast, cartilage matrix osteogenesis was more in dural than dorsal surface of LF. Conclusion In OLF, loss of elastic fibers was associated with proliferation of collagen fibers, fibrosis, chondrogenesis, and osteogenesis. The pathological process initiates in the dorsal surface with chondroid metaplasia gradually elevating the mature cartilage matrix toward the dural surface, where the initial ossification occurs. Disclosure of Interest None declared References Jolly SS. Fluoride balance studies in endemic fluorosis. Fluoride 1976;8:138–147 Jolly SS, Singh BM, Mathur OC, Malhotra KC. Epidemiological, clinical, and biochemical study of endemic dental and skeletal fluorosis in punjab. BMJ 1968;4(5628):427–429 Jolly SS, Singh ID, Prasad S, Sharma R, Singh BM, Mathur OC. An epidemiological study of endemic fluorosis in Punjab. Indian J Med Res 1969;57(7):1333–1346 Jolly SS, Prasad S, Sharma R, Rai B. Human fluoride intoxication in the Punjab. Fluoride 1971;4:64–79 Jolly SS, Prasad S, Sharma R, Chander R. Endemic fluorosis in Punjab-skeletal aspects. Fluoride 1973;6:4–18 Naidu MRC, Reddy DR, Reddy PK, Sastry Kolluri VR. [Fluorotic cervical spinal cord disease]. Rev Chir Orthop Repar Appar Mot 1989;75(4):228–231 Siddiqui AH. Fluorosis in Nalgonda District, Hyderabad-Deccan. BMJ 1955;2(4953):1408–1413

Anisotropic in vitro vessel model using poly(vinyl alcohol) hydro gel and mesh material

AbstractIn the present study, the authors fabricated straight multilayer hybrid tubular in vitro vessel models (inner diameter Din = 10 mm; thickness T = 4 mm) composed of poly(vinyl alcohol) hydrogel (PVA‐H) and anisotropic mesh materials. The authors performed tensile, stress‐relaxation and cyclic‐tensile tests using axial and circumferential test pieces as well as pressure‐diameter (P‐D) tests using tubular test piece. In the tensile and stress‐relaxation tests, the anisotropic and nonlinear mechanical properties and hysteresis characteristic of the in vitro models were confirmed. The in vitro models also showed behavior qualitatively similar to that of native arteries in cycle‐tensile and P‐D tests. These results demonstrate that the mechanical properties of native vessels can be duplicated in an in vitro model by controlling the components of the mesh material, the orientation of elastic fibers in the mesh material, and the concentration and thickness of PVA‐H layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Functional morphology of the sound‐generating labia in the syrinx of two songbird species

In songbirds, two sound sources inside the syrinx are used to produce the primary sound. Laterally positioned labia are passively set into vibration, thus interrupting a passing air stream. Together with subsyringeal pressure, the size and tension of the labia determine the spectral characteristics of the primary sound. Very little is known about how the histological composition and morphology of the labia affect their function as sound generators. Here we related the size and microstructure of the labia to their acoustic function in two songbird species with different acoustic characteristics, the white-crowned sparrow and zebra finch. Histological serial sections of the syrinx and different staining techniques were used to identify collagen, elastin and hyaluronan as extracellular matrix components. The distribution and orientation of elastic fibers indicated that the labia in white-crowned sparrows are multi-layered structures, whereas they are more uniformly structured in the zebra finch. Collagen and hyaluronan were evenly distributed in both species. A multi-layered composition could give rise to complex viscoelastic properties of each sound source. We also measured labia size. Variability was found along the dorso-ventral axis in both species. Lateral asymmetry was identified in some individuals but not consistently at the species level. Different size between the left and right sound sources could provide a morphological basis for the acoustic specialization of each sound generator, but only in some individuals. The inconsistency of its presence requires the investigation of alternative explanations, e.g. differences in viscoelastic properties of the labia of the left and right syrinx. Furthermore, we identified attachments of syringeal muscles to the labia as well as to bronchial half rings and suggest a mechanism for their biomechanical function.

Non‐invasive multiphoton imaging of extracellular matrix structures

Multiphoton microscopy has become a powerful method for the artifact-free, nondestructive evaluation of deep-tissue cells and extracellular matrix (ECM) structures in their native environment. By interacting with highly non-centrosymmetric molecular assemblies such as fibrillar collagen, the non-linear process called second harmonic generation (SHG) has also proven to be an important diagnostic tool for the visualization of ECM compartments in situ with submicron resolution without the need for tissue processing. This review reports on applications of multiphoton-induced autofluorescence and SHG microscopy to identify collagen and elastic fiber orientation in native, tissue-engineered and processed, as well as healthy and diseased, tissues and organs. SHG signal profiling was used to quantify ECM damage in various cardiovascular and exocrine tissues, as well as cartilage. These novel imaging modalities open the general possibility of high-resolution in situ and more important in vivo imaging of ECM structures, cells and intracellular organelles in living intact tissues.

Elastic tissues of the intervertebral disc.

Elastic fibres have been generally considered to play no significant role in the mechanical functioning of the intervertebral disc since earlier studies reported that the elastic fibre network was sparse and irregular. However, a recent study has reported that the network is highly organized and that the distribution and orientation of elastic fibres varies from region to region. In the annulus, elastic fibres appear densely distributed in the region between the lamellae and also in 'bridges' across the lamellae. They are also organized in the nucleus where long straight fibres are radially oriented and anchor perpendicularly or obliquely into the cartilaginous endplate. Immunohistochemistry using specific antibodies indicates that elastin is present in the network, as is fibrillin. Biochemical studies show, however, that the amino acid composition of the residue remaining after alkaline (NaOH) extraction or CNBr digestion contains a higher concentration of polar amino acids than ligamentum nuchal elastin. The composition of the residue suggests that disc elastin may cross-link strongly with some other matrix components. With such coupling, it is thought that elastic fibres could play a significant mechanical role even though overall elastin is less than 5% of the total dry weight of the disc.

Lamina Propria of the Mucosa of Benign Lesions of the Vocal Folds

To demonstrate a correlation between the duration and specific pattern of trauma of benign lesions of the vocal folds and their histopathologic appearance. Benign lesions of the vocal folds have various macroscopic appearances. Investigations demonstrate characteristic histopathologic features for three clinically well-defined lesions: 1) vocal fold polyps, 2) Reinke edema, and 3) vocal fold nodules. It is expected that additional histological stainings can contribute to additional insight into the pathophysiology of these lesions. Retrospective. Histological stainings were used to study the constitution of the lamina propria of the mucosa: Verhoeff-van Gieson, Masson trichrome, alcian blue and alcian blue after pretreatment with hyaluronidase. Estimation of the age of a lesion was not possible. Specific observations: 1) accumulation of hyaluronic acid around vessels occurred uniquely in polyps and 2) transverse orientation of elastic fibers was more often seen in vocal fold nodules. Combinations of histopathologic findings were specific to the lesion. The additional stainings support our previous observations, but had no additional discriminating value in making a histopathologic diagnosis.

Alterations of the extracellular matrix of venous walls in varicous veins.

Investigation of changes in normal veins which result in the formation of varicosis led to examination of the histological organisation of the vessel wall and to histomorphological alterations in the region of the extracellular matrix. The expression pattern of the matrix proteins collagen IV, fibronectin, laminin, tenascin, and undulin as well as the structure and orientation of elastic fibres were determined by means of immunohistochemical staining. All varices exhibited an increased expression pattern in comparison to healthy veins. The venous vessel wall was often non-homogeneously enlarged. The intima was always more involved than the media and showed enhanced accumulation, whereas, the adventitia was not influenced by the pathological process. Collagen IV exhibited an early accumulation, especially in the subendothelial region. The other matrix proteins demonstrated an increase in fibre propagation parallel to the enlargement of the vessel wall. Essentially, an augmented de novo synthesis of fibres with an irregular arrangement and the formation of local plaques was found. Elastic fibres were enhanced by slight involvement of the vessel wall and were reduced and fragmented during increased involvement of the venous wall which explained the rigidity of varices in contrast to normal veins.

Origin and propagation of elastogenesis in the developing cardiovascular system.

Ectomesenchyme derived from cardiac neural crest is critical to aorticopulmonary septation in the heart. However, any unique contribution of the cardiac ectomesenchyme to the extracellular matrix of the conotruncus has not been demonstrated previously. In this study the chronology and topography of soluble tropoelastin (STE) and the aldehyde-rich protein (ARP) of the elastic connective tissues have been examined in the chick embryo, stages 21-38, and in the quail-chick chimera, stages 24-35 (quail neural fold grafted onto a chick embryo). STE was located with immunofluorescence histochemistry, and ARP with Schiff's reagent. With these procedures prevenient sites of elastin synthesis are observed readily. The results show that the myocardium proper appears to have a role in the instigation of elastogenesis and in elastic fiber orientation; that the mesenchymal cells whose matrix contains elastic fibers are ectomesenchymal, of neural crest origin; and that elastin is deployed in an orderly proximal-distal sequence. It is hypothesized that elastogenesis is a critical event in aorticopulmonary septation.

Orientation of elastic fibers in the human cervix

We have determined the microanatomy of the cervix in relation to elastic fibers by serial dissection of human cervix in three tissue planes: cross, sagittal, and frontal sections. Analysis suggests that elastin is localized to specific regions of the uterine cervix and not dispersed throughout the connective tissue stroma. By Musto stain the majority of elastic fibers are noted to be oriented from the external os to the periphery and from there in a band upward toward the internal os where they become sparse in the area of the cervix with the greatest amount of smooth muscle just below the internal os. Elastic fibers were noted to be sparsely distributed in the cervical stroma.

Elastic tissue in the temporomandibular disc of miniature swine

Six intraarticular discs from the temporomandibular joints of three miniature swine were examined for the distribution and orientation of elastic fibres. Elastic tissue was abundant in the posterior portion of the disc, less tissue was seen anteriorly and marginally and the least amount in the central portion.