Elastic Fiber

The elastic fiber is a complex extracellular matrix structure that imparts elastic properties to tissues.

From: Methods in Cell Biology , 2018

Wound Healing

Courtney M. Townsend JR., MD , in Sabiston Textbook of Surgery , 2022

Elastic fibers

Tissues such as skin, blood vessels, and lungs require strength and elasticity to function. Elastic fibers in the ECM of these tissues provide the resilience to allow recoil after transient stretching.

Elastic fibers are predominantly composed of elastin, a highly hydrophobic protein (≈750 amino acids long). Soluble tropoelastin is secreted into the extracellular space, where it forms lysine cross-links to other tropoelastin molecules to generate a large network of elastin fibers and sheets. Elastin is composed of hydrophobic and alanine-rich and lysine-rich α-helical segments that alternate along the polypeptide chain. The hydrophobic segments are responsible for the elastic properties of the molecule. The alanine-rich and lysine-rich α-helical segments form cross-links between adjacent molecules. Although the proposed conformation of elastin molecules is controversial, the predominant theory is that the elastin polypeptide chain adopts a random coil conformation that allows the network to stretch and recoil like a rubber band. Elastic fibers consist of an elastin core covered by a sheath of microfibrils, which are composed of several distinct glycoproteins such as fibrillin. Elastin-binding fibrillin is essential for the integrity of the elastic fibers.

Microfibrils appear before elastin in developing tissues and seem to form a scaffold on which the secreted elastin molecules are deposited. Elastin is produced early in life, stabilizes, and does notundergo much further synthesis or degradation, with a turnover that approaches the life span. Age-related modification is a result of progressive degradation as the elastic fibers gradually become tortuous, frayed, and porous. Scanning electron microscopy shows that, in humans, the elastic meshwork grows largely undistorted during postnatal growth, during which fibers seem to enlarge in synchrony with growth of the tissue. In circumstances not involving a wound, there is little elastin degradation probably because of the hydrophobic nature of elastin, which makes the interior of this highly folded protein inaccessible. As a result of this high degree of three dimensionality and extensive cross-linking, cleavage must be considerable before there is much loss of elasticity. IGF-1 and TGF-β stimulate the production of elastin. Glucocorticoids and basic FGF reduce the production of elastin in adult skin cells.

Mutations causing a deficiency of elastin protein result in arterial narrowing as a consequence of excessive smooth muscle cell proliferation in the arterial wall (intimal hyperplasia). These findings suggest that the normal elasticity of an artery is needed to prevent the proliferation of these cells. Gene mutations in fibrillin result in Marfan syndrome; severely affected individuals are prone to aortic rupture.

Soft tissues of the musculoskeletal system

Monica Kesson MSc MCSP Cert Ed Cert FE , Elaine Atkins DProf MA MCSP Cert FE , in Orthopaedic Medicine (Second Edition), 2005

Elastic fibres

Elastic fibres, consisting of the protein elastin, are yellow in colour and much thinner and less wavy than collagen fibres. Elastic fibres run singly, never in bundles, and freely branch and anastomose.

Elastic fibres provide the tissue with extensibility so that it can be extended in all directions but if tension is constantly exerted in one direction the elastic fibres may be laid down in sheets known as lamellae, e.g. ligamentum flavum (the 'yellow ligament'). Elastic fibres make up some of the connective tissue fibres of ligaments, joint capsules, fascia and connective tissue sheaths.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780750655637500084

Bronchiectasis

V. Courtney Broaddus MD , in Murray & Nadel's Textbook of Respiratory Medicine , 2022

Bronchial Cartilage or Elastic Fiber Defects

Mounier-Kuhn syndrome, or congenital tracheobronchomegaly, is a rare disorder associated with gross enlargement or dilation of the trachea and segmental bronchi 170 (eFig. 69.8 ). The underlying defect is atrophy and even absence of elastic fibers and smooth muscle tissues of the large airways. 171 Atrophy of the connective tissue between the rings may result in outpouchings (diverticulae) that can serve as reservoirs for recurrent infections. Clinically, Mounier-Kuhn patients may present in early childhood or as late as the fourth decade with recurring lower respiratory infections. The diagnosis is readily made by finding extraordinary dilation of the trachea and central bronchi on CT scans, especially in the presence of tracheal and/or bronchial diverticula (seeeFig. 69.8); for men, transverse and sagittal tracheal diameter greater than 25 mm and greater than 27 mm, respectively, is considered abnormally enlarged, whereas in women, the respective values are greater than 21 mm and greater than 23 mm. 172 Special considerations in management include positive end-expiratory pressure support and silicone or metallic stenting. Lung transplantation is an option, although unique issues associated with Mounier-Kuhn syndrome include recurrent infections when tracheal diverticula are present and difficulty with bronchial anastomosis due to discrepancy in the airway diameters between the donor and the recipient lungs.

Williams-Campbell syndrome arises due to absence of cartilaginous rings in the fourth- to sixth-generation subsegmental bronchi in a symmetrical distribution, although more proximal bronchi may also be involved. 173 In addition to the subsegmental and segmental bronchiectasis, bronchomalacia of the more proximal airways may be seen 174 (eFig. 69.9). Familial cases have been reported in this condition, although the precise genetic defect is not known. Patients with Williams-Campbell syndrome are particularly predisposed to proximal bronchomalacia after transplantation due to the combined effects of cartilage deficiency in their mainstem bronchi in addition to the usual decrement of blood supply to the proximal airways due to loss of collateral circulation of the transplanted lung. 175

Extracellular matrix

Frans Van den Berg , in Fascia: The Tensional Network of the Human Body, 2012

Elastic fiber microstructure

Elastic fibers consist of an amorphic mass of elastin which is surrounded by elastic microfibrils. The microfibrils serve to orient the elastin in the formation of the elastic fibers. Elastic fibers are very branching and have many connections to each other. This creates the net-like structure. They can extend by 100 to 150%. As they extend, they store potential energy in order to be able to return to their original form after stress. Three stages have been distinguished in the synthesis of elastic fibers: Oxytalan fibers, which occur only as elastic microfibrils; elaunin fibers, i.e., elastic microfibrils with small quantities of elastin; and fully formed elastic fibers. The breaking strength of the elastic fibers is about 300  N/cm2. (Grodzinsky 1983; Fleischmajer et al. 1990; Leadbetter et al. 1990; Currier & Nelson 1992; Aaron & Bolander 2005; Van den Berg 2010).

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780702034251000581

Disorders of elastic tissue

James W. Patterson MD, FACP, FAAD , in Weedon's Skin Pathology , 2021

Formation of elastic fibers

The formation of elastic fibers by fibroblasts, and in some circumstances by smooth muscle cells and chondroblasts, entails several different steps that are still poorly understood. Theoretically, these stages would include the expression of genes coding for elastin polypeptides, various intracellular processes, secretion of the precursor components, and extracellular modifications leading to the assembly of the fibers. 4 Fibulin-5 plays an important role in this assembly by acting as an adaptor molecule between elastin and the matrix scaffold. 16

Elastin is secreted in the form of a precursor, tropoelastin. This is ultimately cross-linked with desmosine to form stable elastin. 17 The formation of desmosine requires the copper-dependent enzyme lysyl oxidase. 17 Defects in this enzyme can result from a spectrum of mutations in the adenosine triphosphatase (ATPase) gene(ATP7A), as seen in Menkes' syndrome (seep. 434). Impaired elastinogenesis can also result from other altered transport mechanisms important to elastic fiber assembly. 7 One such example is a deficiency in elastin-binding protein (EBP), which transports tropoelastin from its site of synthesis in the cell to the cell membrane. Costello syndrome (seep. 431) results from a functional deficiency in EBP.

A congenital disorder of glycosylation involving a defect in the biosynthesis ofN- andO-glycans has been reported in several patients with cutis laxa, indicating the role these glycans play in the stability of various extracellular matrix proteins; they may be involved in the glycosylation of fibulin-5. 18

Peri-Partum Changes to Mouse Pubic Symphysis

Paulo Pinto Joazeiro , ... Olga Maria Szymanski Toledo , in The Guide to Investigation of Mouse Pregnancy, 2014

Elastic Fibers

Elastic fibers provide elastic recoil without damage in tissues and organs of the reproductive tract that need to be both strong and extensible to function. However, nongravid PS, although a fibrocartilaginous tissue (which normally does not have elastic fibers), has very thin elastic fibers. These are found sporadically, in dense connective tissue at the most superficial layer of the joint, continuous with the fibrous perichondrium and periosteum. 10,13 The fibrocartilaginous PS of virgin female mice is subject to compressive forces and has little elasticity, 6,29 which is in agreement with the lack of fibers containing elastin in the ECM.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780123944450000345

Glycans and Glycosaminoglycans as Clinical Biomarkers and Therapeutics - Part A

Mohui Wei , Peng George Wang , in Progress in Molecular Biology and Translational Science, 2019

2.7 Modulation of elastic fiber assembly

Elastic fibers are essential extracellular matrix (ECM) macromolecules comprising an elastin core surrounded by a mantle of fibrillin-rich microfibrils. They endow connective tissues such as lungs, arteries, and skin with the critical properties of elasticity and resilience. While the elastin-binding protein (EBP) serves as intracellular molecular chaperone for hydrophobic and nonglycosylated tropoelastin and assures its proper secretion, Neu-1 catalyzes the removal of terminal SA from glycan chains of microfibrillar proteins, unmasking their penultimate galactose residues and forming the structural scaffold of elastic fibers. In turn, the exposed galactose residues interact with the galectin domain of EBP, thereby inducing the release of transported tropoelastin molecules and facilitating their subsequent assembly into elastic fibers. 60,61

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/S1877117318301492

Wound Healing

Jie Li MD PhD , Robert S Kirsner MD PhD , in Surgery of the Skin, 2005

Elastic fibers

Elastic fibers are long, thin, and highly retractile. Elastin, as its name implies, provides elasticity and extensibility to the dermis and assists in recovery from deformation. 59 Elastin is a highly hydrophobic structural protein making up only 2% of the total protein in the dermis. 59 Elastin, lipids, and glycoproteins bind to form microfibrils that serve as the scaffolding or as a foundation for fiber orientation. The microfibrils are infiltrated and surrounded by elastin and fuse to form solid elastic fibers. The characteristically wavy elastic fibers are entwined among collagenous fibers. The orientation of elastin varies from a horizontal arrangement in the deep dermis to a more vertical arrangement closer to the epidermis. With aging, the number of microfibrils declines; however, the amount of the amorphous component, elastin, increases.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780323027526500122

Extraction Techniques and Applications: Biological/Medical and Environmental/Forensics

M. Lai , B. Lü , in Comprehensive Sampling and Sample Preparation, 2012

3.04.6.2.3 Elastic Fibers

Elastic fibers are the third type of fibers in connective tissue. They are highly refractile, wavy, and thinner than collagens. They are slightly eosinophilic by H&E. Under electron microscopy they consist of two components, the central amorphous constituent (elastin) and the microfibrillar component. Atrophy, breaking, splitting, and reduplication of elastic fibers are commonly associated with several pathological conditions, such as emphysema and vascular disease. Under these circumstances, special demonstration methods are invariably required. Elastic fibers can be stained by specific dyes such as orcein, resorcin–fuchsin, and Verhoeff's stain. Weigert's elastic stain is described here.

•

Weigert's elastic stain

Verhoeff's iodine solution: Mix 2   g each of iodine and potassium iodate in a flask, shaking vigorously. Then gradually add distilled water, as five successive 20-ml volumes.

Resorcin–fuchsin solution: Dissolve 2   g of resorcin and 4   g of basic fuchsin in 200   ml of distilled water.

Procedures:

1.

Deparaffinize and hydrate to distilled water.

2.

Stain with Weigert's hematoxylin for 10   min.

3.

Wash in lukewarm running tap water for 10   min and rinse with distilled water.

4.

Stain in resorcin–fuchsin solution for 30–60   min and check microscopically until elastic fibers are black.

5.

Wash off excess stain in 95% alcohol and wash in tap water.

6.

Stain in Van Gieson stain solution for 1   min.

7.

Dehydrate rapidly through 95% alcohol and absolute alcohol twice each, clear, and mount with resin as usual.

Results: Elastic fibers and nuclei are black (Figure 7). Collagen is red. Other tissue structures are yellow.

Figure 7. Weigert's stain for elastic fibers. Note the black elastic fibers in the red background (×100).

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780123813732000703

Systems Toxicologic Pathology

Brian R. Berridge , ... Eugene Herman , in Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition), 2013

Connective Tissue Fibers and Ground Substance

Elastic fibers allow the resilient rebound of the stretched vessel wall while collagen fibers provide tensile strength to the vessel wall. The elastic fibers may be isolated, but are more often arranged in sheets as distinct laminae or layers (internal and external elastic lamina) or as fenestrated lamellae in the walls of elastic arteries. Collagen fibers are scattered in the intima, media, and adventitia. Collagen, mainly type III, is especially abundant in the walls of veins.

The extracellular spaces of the vessel wall contain glycosaminoglycans such as chondroitin sulfate and dermatan sulfate. Arteries contain higher concentrations of ground substance than veins. The ground substance affects permeability across the wall and contributes to the physical properties of the vessel wall.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780124157590000467