Thin Elastic Fibers Research Articles

In vivo multiphoton multiparametric 3D quantification of human skin aging on forearm and face

Quantifying skin aging changes and characterizing its 3D structure and function in a non-invasive way is still a challenging area of research, constantly evolving with the development of imaging methods and image analysis tools. In vivo multiphoton imaging offers means to assess skin constituents in 3D, however prior skin aging studies mostly focused on 2D analyses of dermal fibers through their signals’ intensities or densities. In this work, we designed and implemented multiphoton multiparametric 3D quantification tools for in vivo human skin pigmentation and aging characterization. We first demonstrated that despite the limited field of view of the technic, investigation of 2 regions of interest (ROIs) per zone per volunteer is a good compromise in assessing 3D skin constituents in both epidermis and superficial dermis. We then characterized skin aging on different UV exposed areas—ventral and dorsal forearms, face. The three major facts of aging that are epidermal atrophy, the dermal–epidermal junction (DEJ) flattening and dermal elastosis can be non-invasively quantified and compared. Epidermal morphological changes occur late and were only objectified between extreme age groups. Melanin accumulation in suprabasal layers with age and chronic exposure on ventral and dorsal forearms is less known and appears earlier. Superficial dermal aging changes are mainly elastin density increase, with no obvious change in collagen density, reflected by SHGto2PEF ratio and SAAID index decrease and ImbrN index increase on all skin areas. Analysis of the z-dermal distribution of these parameters highlighted the 2nd 20 µm thickness normalized dermal sub-layer, that follows the DEJ shape, as exhibiting the highest aging differences. Moreover, the 3D ImbrN index allows refining the share of photoaging in global aging on face and the 3D SAAID index on forearm, which elastin or fibrillar collagens densities alone do not allow. Photoaging of the temple area evolves as a function of chronic exposure with a more pronounced increase in elastin density, also structurally modified from thin and straight elastic fibers in young volunteers to dense and compact pattern in older ones. More generally, multiphoton multiparametric 3D skin quantification offers rich spatial information of interest in assessing normal human skin condition and its pathological, external environment or product induced changes.

Spontaneous Elastocapillary Winding of Thin Elastic Fibers in Contact with Bubbles.

We study the elastocapillary interaction between flexible microfibers in contact with bubbles trapped at the surface of a liquid bath. Microfibers placed on top of bubbles are found to migrate to and wrap into a coil around the perimeter of the bubble for certain bubble-fiber size combinations. The wrapping process is spontaneous: the coil spins atop the bubble, thereby drawing in excess fiber floating on the bath. A two-dimensional microfiber coil emerges which increases the lifetime of the bubbles. A simple model incorporating surface and bending energies captures the spontaneous winding process.

Elastic fibers: The missing key to improve engineering concepts for reconstruction of the Nucleus Pulposus in the intervertebral disc

The increasing prevalence of low back pain has imposed a heavy economic burden on global healthcare systems. Intense research activities have been performed for the regeneration of the Nucleus Pulposus (NP) of the IVD; however, tissue-engineered scaffolds have failed to capture the multi-scale structural hierarchy of the native tissue. The current study revealed for the first time, that elastic fibers form a network across the NP consisting of straight and thick parallel fibers that were interconnected by wavy fine fibers and strands. Both straight fibers and twisted strands were regularly merged or branched to form a fine elastic network across the NP. As a key structural feature, ultrathin (53 ± 7 nm), thin (215 ± 20 nm), and thick (890 ± 12 nm) elastic fibers were observed in the NP. While our quantitative analysis for measurement of the thickness of elastic fibers revealed no significant differences (p < 0.633), the preferential orientation of fibers was found to be significantly different (p < 0.001) across the NP. The distribution of orientation for the elastic fibers in the NP represented one major organized angle of orientation except for the central NP. We found that the distribution of elastic fibers in the central NP was different from those located in the peripheral regions representing two symmetrically organized major peaks (±45⁰). No significant differences in the maximum fiber count at the major angles of orientation (±45⁰) were observed for both peripheral (p = 0.427) and central NP (p = 0.788). Based on these new findings a structural model for the elastic fibers in the NP was proposed. The geometrical presentation, along with the distribution of elastic fibers orientation, resulting from the present study identifies the ultrastructural organization of elastic fibers in the NP important towards understanding their mechanical role which is still under investigation. Given the results of this new geometrical analysis, more-accurate multiscale finite element models can now be developed, which will provide new insights into the mechanobiology of the IVD. In addition, the results of this study can potentially be used for the fabrication of bio-inspired tissue-engineered scaffolds and IVD models to truly capture the multi-scale structural hierarchy of IVDs. Statement of SignificanceVisualization of elastic fibers in the nucleus of the intervertebral disk under high magnification was not reported before. The present research utilized extracellular matrix partial digestion to address significant gaps in understanding of nucleus microstructure that can potentially be used for the fabrication of bio-inspired tissue-engineered scaffolds and disk models to truly capture the multi-scale structural hierarchy of discs.

Short time insulin treatment post burn improves elastic-collagen rearrangement and reepithelization

ABSTRACTExtensive burn may cause acute resistance to insulin, which accentuates hypermetabolism, impairs glucose metabolism, immune dysfunction and risks of sepsis. To minimize these effects, insulin is used as a treatment. The purpose was to analyze the collagen-elastic arrangement effects of insulin on the burned skin. Wistar rats were assigned in groups: control (C); control with insulin (C + I); scald burn injury (SBI); and SBI with insulin (SBI+ I). SBI were submitted to 45% total body surface area burn and the insulin-treated groups received insulin (5 UI/Kg/day) for 4 or 14 days (d). Insulin levels, glucose tolerance test and HOMA index were determined. The skin sections were analyzed for histophatological and morphoquantitative data. Histopathological findings showed increased reepithelization of SBI+ I and formation of a new muscle layer after 14 days. In the collagen-elastic arrangement, insulin for 4 days increased the volume fraction (Vv) of thin collagen and elastic fibers. After 14 days, independently of injury, insulin decreased the elastic fibers. Insulin was able to reverse damages in the collagen-elastic rearrangement and stimulate reepithelization after 4 days. Untreated scald-burned animals showed higher Vv of thick collagen after 4 days, while those treated had a higher Vv of thin collagen. The Vv of elastic fibers was increased in SBI+ I for 4 days. In conclusion, insulin treatment was able to stimulate reepithelization. It also reversed the damages to the collagen-elastic arrangement in the scald-burned group, improving the organization of thin collagen and increasing the Vv of elastic fibers in the injured group treated with insulin for a short time, that is, for 4 days.

Elastic Staining in Differentiating Between Follicular Streamers and Follicular Scars in Horizontal Scalp Biopsy Sections.

Accurate identification of follicular streamers versus follicular scars on horizontal scalp biopsy sections is important to differentiate between cicatricial and noncicatricial alopecias. However, distinguishing between them can be difficult especially in nonoptimal specimens. The utility of elastic Verhoeff-Van Gieson (EVG) stain in cicatricial alopecias has been described on vertical sections, but its evaluation on horizontal sections has not been performed. Sixty-four cicatricial alopecias (25 lichen planopilaris, 29 central centrifugal cicatricial alopecias, and 10 discoid lupus erythematosus) and 53 noncicatricial alopecias (34 androgenic alopecia, 8 telogen effluvium, and 11 alopecia areata) were identified, and EVG staining was performed on horizontal sections. In follicular streamers, EVG highlighted an intact elastic network composed of delicate and thin elastic fibers circumferentially surrounding the angiofibrotic streamer without elastic network attenuation, loss, clumping, thickening, or recoil. In follicular scars, EVG demonstrated central attenuation and loss of the elastic network with peripheral clumping and recoil of elastic fibers. In cases where distinguishing between follicular streamers and scars is difficult, EVG may be a helpful adjunctive tool in this regard and aid in allowing better discrimination between cicatricial and noncicatricial alopecias.

Acrokeratoelastoidosis

Acrokeratoelastoidosis is a rare palmoplantar keratoderma. We report the case of a 32-year old man with multiple keratotic papules and plaques on the peripheral margins of his hands and feet. Histopathologic evaluation showed compact orthokeratosis; Verhoeff van Gieson stain showed thin and fragmented elastic fibers. The differential diagnosis includes focal acral hyperkeratosis, which has a similar presentation but with normal elastic fibers. Treatment of acrokeratoelastoidosis is often disappointing, with minimal response to topical glucocorticoids, keratolytics, retinoids, cryotherapy, and lasers.

A histochemical study of ultraviolet B irradiation and Origanum hypericifolium oil applied to the skin of mice

Ultraviolet (UV) rays cause skin damage. Chronic exposure to UV irradiation causes decreased collagen synthesis, degenerative changes in collagen bundles, accumulation of elastotic material and increased epidermal thickness. Origanum hypericifolium, an endemic Turkish plant, belongs to Lamiaceae family. The main constituents of its oil are monoterpenes including cymene, carvacrol, thymol and γ-terpinene. The effects of undiluted O. hypericifolium oil on UVB irradiated skin of mice were investigated histochemically. Four groups of female BALB/c mice, whose dorsal hair was shaved, were allocated as follows: non-UVB irradiated (Group 1), UVB-irradiated (Group 2), O. hypericifolium oil treated (Group 3), and O. hypericifolium oil treated and UVB irradiated (Group 4). Sections of dorsal skin samples were stained with Mallory's phosphotungstic acid hematoxylin for collagen fibers and Taenzer-Unna orcein for elastic fibers. Sections also were stained with hematoxylin and eosin to measure epidermal thickness. We observed intense staining of collagen and homogeneous, scattered thin elastic fibers in Group 1; scattered and weakly stained collagen and curled, amorphous, accumulate elastic fibers in Group 2; and intense staining of collagen in Groups 3 and 4. Accumulation of elastic fibers in the dermis was unremarkable in Groups 3 and 4. In Groups 3 and 4, O. hypericifolium oil treatment thickened the epidermis. Epidermal thickness was greatest in Group 4. We suggest that O. hypericifolium oil may block UVB induced alterations of collagen and elastic fibers, and increase epidermal thickness.

Asymptotics for thin elastic fibers in unilateral contact

AbstractWhat is the contact condition in a 1D beam‐model and is it possible to obtain the frictional moments and forces from the 3D traction? If it is possible does the cross‐section of the beams influence these values? These questions motivate to study the dimension reduction of a 3D contact problem for beams. This paper is a continuation of [1]. In [1] the asymptotic dimension reduction of a Robin‐type elasticity boundary value problem was presented. In this work the explicit relation between a 3D contact problem and a 3D Robin‐type elasticity boundary value problem are established and the 1D equations derived in [1] are interpreted as 1D contact conditions, further some numerical examples are shown. (© 2012 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Initial lesions of the elastic fibers and extracellular matrix in varicose veins: an inmunohistochemical and confocal microscopy study

Chronic venous insufficiency (CVI) has high morbidity in middle and advanced age population. We studied varicose vein alterations in early stages to identify possible therapeutic targets. Saphenous veins from 10 patients were classified according to Color Doppler in proximal segment with lesions (Varicose vein, VV) and distal (normal vein, NV). We analyzed extracellular matrix (ECM), elastic fibers, collagen I and IV and SMC in sections stained with Masson trichrome, orcein, sirius red and collagen I and IV antibodies. Elastin was studied with confocal microscopy in intact veins (autofluorescence). Compared to NV, VV intima shows multifocal areas of endothelial denudation, deposition of powdery collagen and elastic material and short and thin elastic fibers. VV media has SMC atrophy, increased immature ECM deposition with few and small collagen I fibers and incomplete elastogenesis. Adventitia is thick with abundant mature collagen I and deposition and increased thick and irregularly distributed elastic fibers. Some areas of the distal NV segment also exhibited some of these abnormalities. We conclude that initial multifocal degeneration of adventitial elastic fibers, intimal elastogenesis and progressive atrophy of SMC are processes perpetuating CVI and irreversible lesions. Funding: Universidad Autónoma de Madrid (UAM/32).

A case report of coronary arteriovenous fistulas with an unruptured coronary artery aneurysm successfully treated by surgery.

A 58-year-old female with a history of Wolff-Parkinson-White syndrome presented at our institution with palpitations and chest pain. Electrocardiography revealed paroxysmal supraventricular tachycardia with a heart rate of 188 beats/min. Antiarrhythmic drugs were ineffective, and tachycardia was resolved by electrical cardioversion. Transthoracic echocardiography revealed abnormal vessels around the right coronary artery (RCA) and pulmonary artery (PA); in addition, we suspected coronary arteriovenous fistula (CAVF). Coronary angiography and coronary computed tomography revealed dilated fistula vessels, with a 1 cm saccular aneurysm around the RCA, originating from the proximal RCA and left anterior descending artery into the main trunk of PA. Therefore, we confirmed the diagnosis of CAVF with an unruptured aneurysm. We surgically ligated and clipped the fistula vessels and resected the aneurysm. The resected aneurysm measured 1 × 1 cm in size. Pathological examination of the resected aneurysm revealed hypertrophic walls comprising proliferating fibroblasts cells thin elastic fibers. Very few atherosclerotic changes manifested in the aneurysm walls. We report the case of a patient with CAVF and an unruptured coronary artery aneurysm who was successfully treated by surgery.

Implicit mechanistic role of the collagen, smooth muscle, and elastic tissue components in strengthening the air and blood capillaries of the avian lung.

To identify the forces that may exist in the parabronchus of the avian lung and that which may explain the reported strengths of the terminal respiratory units, the air capillaries and the blood capillaries, the arrangement of the parabronchial collagen fibers (CF) of the lung of the domestic fowl, Gallus gallus variant domesticus was investigated by discriminatory staining, selective alkali digestion, and vascular casting followed by alkali digestion. On the luminal circumference, the atrial and the infundibular CF are directly connected to the smooth muscle fibers and the elastic tissue fibers. The CF in this part of the parabronchus form the internal column (the axial scaffold), whereas the CF in the interparabronchial septa and those associated with the walls of the interparabronchial blood vessels form the external, i.e. the peripheral, parabronchial CF scaffold. Thin CF penetrate the exchange tissue directly from the interparabronchial septa and indirectly by accompanying the intraparabronchial blood vessels. Forming a dense network that supports the air and blood capillaries, the CF weave through the exchange tissue. The exchange tissue, specifically the air and blood capillaries, is effectively suspended between CF pillars by an intricate system of thin CF, elastic and smooth muscle fibers. The CF course through the basement membranes of the walls of the blood and air capillaries. Based on the architecture of the smooth muscle fibers, the CF, the elastic muscle fibers, and structures like the interparabronchial septa and their associated blood vessels, it is envisaged that dynamic tensional, resistive, and compressive forces exist in the parabronchus, forming a tensegrity (tension integrity) system that gives the lung rigidity while strengthening the air and blood capillaries.

Elastic Fibers in Reinke's Edema

We describe the distribution of elastic system fibers in the superficial layer of the lamina propria of Reinke's edema, as compared with normal vocal folds. Weigert's resorcin-fuchsin stain after oxidation with 10% oxone was used to study the arrangement of elastic fibers. The findings were categorized and afterward compared with the severity of Reinke's edema. Analysis of 20 specimens of vocal folds with Reinke's edema showed that the network of thin elastic fibers in Reinke's space lost their undulated appearance and had a tangled aspect. In addition, these fibers were no longer parallel to the epithelial basement membrane, but had a random distribution scattered throughout Reinke's space. The elastic fiber network immediately below the epithelial basement membrane also appeared more fragmented in Reinke's edema because of some alteration in organization combined with the 5-microm-thick histologic sectioning plane. No significant difference in the degree of elastic system fiber disarrangement was observed between severity grades II and III (p = 0.382). Large areas of disarrangement were predominant (80% of cases). The disarrangement of elastic fibers in Reinke's edema may cause insufficient tissue resistance and resilience, contributing to the hypermobility observed in Reinke's edema.

Elastic fiber pattern in regressing melanoma: a histochemical and immunohistochemical study

Although histopathologic identification of regression of melanoma is usually straightforward, sometimes it can be difficult to distinguish it from scarring fibrosis. Therefore, this study investigates the elastic fiber pattern in melanomas associated with either regression or scars. We compared 33 invasive melanomas with the fibrosing stage of regression to 10 cases of invasive melanomas with scarring fibrosis. None of the regression cases had a prior surgical procedure. Elastic fiber patterns were evaluated with Verhoeff's elastic van Gieson stain (EVG) and elastin immunostain. Elastin immunostain was superior to EVG in revealing the elastic fiber patterns. Both regression and scars had decreased to absent elastic fibers in the areas of fibrosis. However, areas of regression had a well-defined compressed layer of thin elastic fibers pushed down from the papillary dermis to the base of the fibrosis. In contrast, the base of scars lacked this compressed elastic layer and had instead an abrupt transition to the thick elastic fibers of the spared reticular dermis. We have identified distinct changes of the elastic tissue network, which more accurately define the presence of regression in melanoma and distinguish it from scarring fibrosis.

The use of elastin immunostain improves the evaluation of melanomas associated with nevi

Twenty to 30% of malignant melanomas are associated with melanocytic nevi; however, sometimes it is difficult to distinguish the melanoma from the nevus by routine histology. We have previously described distinctive patterns of elastic fibers in nevi and in melanomas. We analyzed elastic fiber patterns using elastin immunostain and elastic van Gieson (EVG) stain in 30 cases of invasive melanomas associated with nevi, 12 control melanocytic nevi and 14 control invasive melanomas. Elastin immunostain was superior to EVG in showing the elastic fiber patterns. In nevi, the elastic fibers were preserved between nests and often around individual melanocytes. In contrast, melanomas had markedly decreased elastic fibers in the stroma and within the nests of melanocytes. The melanoma pushed down the pre-existing thin elastic fibers of the papillary dermis, forming a compressed layer at its base, which separated the melanoma from the nevus. On sun-damaged skin, the solar elastosis had similar elastin and EVG patterns. In three cases with dense inflammation, the layer of elastic fibers between melanoma and nevus was still present but less evident. The distinctive patterns of elastic fibers, best shown by the elastin immunostain, were helpful in evaluating melanomas associated with melanocytic nevi.

Revisiting the Trabecular Meshwork in the Eyes of the Developing Human

Background: The trabecular meshwork (TM) is a specialized tissue which is crucial to maintain ocular health (e.g. intraocular pressure) and to sustain optical clarity. Since collagen and elastic fibers are the primary structural components of the tissue, the characterization of these fibers in the fetal eye would advance our understanding of the basic morphology and further congenital studies related to the TM. Aims: To reveal the early development of the human fetal TM. Results: The results showed the presence of circular (radial) and longitudinal collagen fibers as well as trabecular cells in the TM by 12 weeks of gestation. By 26 weeks, the venous system connected with Schlemm’s canal and thin elastic fibers began to form. At birth, longitudinal collagen fibers linked with each other to form long strands. There was also evidence of an increase in circular (or radial) collagen fibers in the TM. Conclusion: The present study characterized the developmental and morphological changes in the genesis of the fetal TM in terms of growth in collagen and elastic fibers. The elastic fibers were found to exist in small quantity at birth, and, thus, any increase in these fibers to maturity is likely to occur after birth.

Significant Decrease in Tropoelastin Gene Expression in Fibroblasts from a Japanese Costello Syndrome Patient with Impaired Elastogenesis and Enhanced Proliferation

Costello syndrome is a connective tissue disorder associated with sparse, thin, and fragmented elastic fibers in tissues. In this study we demonstrated a significant decrease in the expression of tropoelastin mRNA in fibroblasts derived from a Japanese Costello syndrome patient with impaired elastogenesis and enhanced proliferation. In contrast, there were no changes in expression of the Harvey ras (HRAS), fibrillin-1, fibulin-5, microfibril-associated glycoprotein-1 (MAGP-1), lysyl oxidase (LOX), or 67-kDa non-integrin elastin-binding protein (EBP) gene. The proliferative activity of the Costello fibroblasts was about 4-fold higher than that of the normal and pathological control ones. However, no mutations were detected in the coding region of HRAS mRNA. Transduction of the bovine tropoelastin (bTE) gene with the lentiviral vector restored the elastic fiber formation and decreased the growth rate in the Costello fibroblasts. These results strongly suggest that the defect of human tropoelastin (hTE) gene expression should induce the impaired elastogenesis and enhanced proliferation of Costello fibroblasts, and that a primary cause other than the HRAS gene mutation should contribute to the pathogenesis in the present Costello case.

Intermittent short-duration exposure to low wall shear stress induces intimal thickening in arteries exposed to chronic high shear stress

We sought to determine whether intermittent short-duration exposure to low wall shear stress could induce intimal thickening in arteries chronically exposed to high shear stress. An arteriovenous fistula (AVF) was created between the left common carotid artery and the corresponding external jugular vein in 20 Japanese white male rabbits. After 4 weeks, blood flow was increased 10-fold to 182 ± 39 ml/min and shear stress was increased to 33.4 ± 13 dyn/cm 2. The AVF was then occluded for 1 h by finger compression with an 85% reduction in carotid artery blood flow (27 ± 7 ml/min) and a reduction in wall shear stress to 4.9 ± 1.7 dyn/cm 2 ( P < 0.0001). Release of finger compression restored flow to the AVF and high shear stress to the carotid artery. This procedure was repeated at weekly intervals with a cumulative total of 4 h of low shear stress exposure. Arteries exposed to intermittent low shear stress developed a layer of intimal thickening which consisted of 3–4 layers of smooth muscle cells lined with thin elastic fibers and medial hyperplasia. Control arteries exposed to 8 weeks of continuous high shear had no intimal thickening. Transient exposure to low shear stress upregulated TGF-β1, MMP-2, -14, and TIMP-2 gene expression while MMP-9 expression was downregulated. We conclude that repeated, intermittent short-duration exposure to low shear stress in the setting of high flow and high shear stress can induce arterial intimal thickening. Short-duration alterations in hemodynamic forces can induce rapid vascular cell message expression, which may effect arterial remodeling. This experiment suggests that a threshold value of 5 dyn/cm 2 may be needed in order to initiate and sustain the intimal thickening response.

Innervation and functional characteristics of connective tissues, especially elastic fibers, in human fetal thoracic intervertebral articular capsule and its surroundings.

The articular capsules between the thoracic vertebrae, which have physiologically different functions from those of other levels of the vertebrae, have yet to be subjected to neuro-anatomical and fine structural analysis. In the present study, we analyzed serial frozen sections of decalcified thoracic vertebrae in human fetuses, and identified the articular capsule tissue with its unique distribution of elastic fibers. The fine structure of the elastic fibers was studied by transmission electron microscopy. In the early-stage fetus, the fibrous membrane forming the lateral intervertebral articular capsule contained abundant thin elastic fibers consisting of microfibrils. In the late-stage fetus, the lateral capsule of fibrous membrane was occupied by thick elastic fibers. A medial articular capsule, namely the ligamenta flava, contained numerous thick elastic fibers in both early and late-stage fetuses. The distributional differences in nerve fibers between early and late-stage fetuses were determined by immunostaining, using antibodies raised against protein gene product 9.5 (PGP 9.5; ubiquitin carboxyl-terminal hydrolase). Innervation by PGP 9.5 immunoreactive fibers was limited to the areas of the articular capsules near the blood vessels, which may indicate their functional relation with blood flow. No PGP 9.5 immunoreactive fibers were found in the ligamenta flava of the late-stage fetus. Innervation might be directly involved in the development of the intervertebral articular capsules in normal human fetuses.

Three-dimensional analysis of alveolar structure in usual interstitial pneumonia

The etiology of usual interstitial pneumonia (UIP), a progressive lung disease, remains unclear. We examined alveolar structure in UIP three-dimensionally. Lung biopsy specimens from five patients with idiopathic pulmonary fibrosis were used. Sections 150-microm thick were stained with elastica solution for elastic fibers, with alpha-smooth muscle actin antibody for myofibroblasts, with anti-Thomsen-Friedenreich antibody for type-II pneumocytes and with anti-CD34 antibody for blood vessels. We examined them three-dimensionally using a laser confocal microscope or light microscope. In the fibrotic lesions, the thick elastic fibers forming the alveolar framework were not particularly dense considering the reduction in alveolar volume. Near the fibrotic lesions, some of the thin elastic fibers in the alveolar wall were slightly sinuous and ended with rounded tips. Type-II pneumocytes had proliferated and were distributed uniformly over the alveolar surface. Smooth muscle actin filaments were detected only around the alveolar orifice. These findings show that in UIP destruction of the elastic fiber framework of the alveoli may lead to irreversible focal alveolar collapse after damage to the alveolar epithelial cells, and proliferation of type-II pneumocytes may be involved with this elastolysis.

Linear Focal Elastosis

Figure 1. Semithin (1-μm) section demonstrated increased amount of thin and fragmented elastic fibers (toluidine blue stain, ×240). Figure 2. Electron microscopy shows irregular fragmented and degenerating elastic fibers (original magnification ×9000). fibers characterized by thin, wavy, elongated as well as fragmented elastic fiber bundles. von Kossa's stain for calcium deposition was negative. Electron microscopy revealed numerous elongated thin, irregular, and fragmented elastic fibers ( Figure 2 ). Some fragments demonstrated central electron-lucent homogenous material with focal densities. Others showed irregularly shaped swollen fibers with degenerative changes. In addition, many elastic fibers were observed in close association and sometimes in contact with fibroblasts. Finely granular electron-dense material was observed in the matrix surrounding these elastic fibers. Fine cytoplasmic microfibrils were noted in the rare fibroblasts with associated elastic fibers. Comment. Burket et al 1 coined the term linear focal elastosis and proposed the synonym elastotic striae . At first glance, the lesions resemble