scholarly journals Quantitative mapping of collagen fiber alignment in thick tissue samples using transmission polarized-light microscopy

2016 ◽  
Vol 21 (7) ◽  
pp. 071111 ◽  
Author(s):  
Dmitry D. Yakovlev ◽  
Marina E. Shvachkina ◽  
Maria M. Sherman ◽  
Andrey V. Spivak ◽  
Alexander B. Pravdin ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Polarized Light Microscopy ◽  
Tissue Samples ◽  
Fiber Alignment ◽  
Quantitative Mapping ◽  
Collagen Fiber Alignment

scholarly journals Polarized light microscopy for 3-dimensional mapping of collagen fiber architecture in ocular tissues

2018 ◽  
Vol 11 (8) ◽  
pp. e201700356 ◽  
Author(s):  
Bin Yang ◽  
Ning-Jiun Jan ◽  
Bryn Brazile ◽  
Andrew Voorhees ◽  
Kira L. Lathrop ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Polarized Light Microscopy ◽  
Fiber Architecture ◽  
Ocular Tissues ◽  
3 Dimensional ◽  
Dimensional Mapping

scholarly journals Real-time imaging of optic nerve head collagen microstructure and biomechanics using instant polarized light microscopy

2021 ◽  
Author(s):  
Po-Yi Lee ◽  
Bin Yang ◽  
Yi Hua ◽  
Susannah Waxman ◽  
Ziyi Zhu ◽  
...  
Keyword(s):  
Optic Nerve ◽  
Light Microscopy ◽  
Optic Nerve Head ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Local Deformation ◽  
Polarized Light Microscopy ◽  
Frame Rate ◽  
High Temporal Resolution ◽  
Color Analysis

Current tools lack the temporal or spatial resolution necessary to image many important aspects of the architecture and dynamics of the optic nerve head (ONH). We evaluated the potential of instant polarized light microscopy (IPOL) to overcome these limitations by leveraging the ability to capture collagen fiber orientation and density in a single image. Coronal sections through the ONH of fresh normal sheep eyes were imaged using IPOL while they were stretched using custom uniaxial or biaxial micro-stretch devices. IPOL allows identifying ONH collagen architectural details, such as fiber interweaving and crimp, and has high temporal resolution, limited only by the frame rate of the camera. Local collagen fiber orientations and deformations were quantified using color analysis and image tracking techniques. We quantified stretch-induced collagen uncrimping of lamina cribrosa (LC) and peripapillary sclera (PPS), and changes in LC pore size (area) and shape (convexity and aspect ratio). The simultaneous high spatial and temporal resolutions of IPOL revealed complex ONH biomechanics: i) stretch-induced local deformation of the PPS was nonlinear and nonaffine. ii) under load the crimped collagen fibers in the PPS and LC straightened, without torsion and with only small rotations. iii) stretch-induced LC pore deformation was anisotropic and heterogeneous among pores. Overall, with stretch the pores were became larger, more convex, and more circular. We have demonstrated that IPOL reveals details of collagen morphology and mechanics under dynamic loading previously out of reach. IPOL can detect stretch-induced collagen uncrimping and other elements of the tissue nonlinear mechanical behavior. IPOL showed changes in pore morphology and collagen architecture that will help improve understanding of how LC tissue responds to load.

Automatic Evaluation of Collagen Fiber Directions from Polarized Light Microscopy Images

2015 ◽  
Vol 21 (4) ◽  
pp. 863-875 ◽  
Author(s):  
Kamil Novak ◽  
Stanislav Polzer ◽  
Michal Tichy ◽  
Jiri Bursa
Keyword(s):  
Light Microscopy ◽  
Achilles Tendon ◽  
Collagen Fiber ◽  
Polarized Light ◽  
Polarized Light Microscopy ◽  
Collagen Content ◽  
Aortic Tissue ◽  
Collagen Orientation ◽  
Automated Method ◽  
Microscopy Images

AbstractMechanical properties of the arterial wall depend largely on orientation and density of collagen fiber bundles. Several methods have been developed for observation of collagen orientation and density; the most frequently applied collagen-specific manual approach is based on polarized light (PL). However, it is very time consuming and the results are operator dependent. We have proposed a new automated method for evaluation of collagen fiber direction from two-dimensional polarized light microscopy images (2D PLM). The algorithm has been verified against artificial images and validated against manual measurements. Finally the collagen content has been estimated. The proposed algorithm was capable of estimating orientation of some 35 k points in 15 min when applied to aortic tissue and over 500 k points in 35 min for Achilles tendon. The average angular disagreement between each operator and the algorithm was −9.3±8.6° and −3.8±8.6° in the case of aortic tissue and −1.6±6.4° and 2.6±7.8° for Achilles tendon. Estimated mean collagen content was 30.3±5.8% and 94.3±2.7% for aortic media and Achilles tendon, respectively. The proposed automated approach is operator independent and several orders faster than manual measurements and therefore has the potential to replace manual measurements of collagen orientation via PLM.

scholarly journals Full-Range Optical Imaging of Planar Collagen Fiber Orientation Using Polarized Light Microscopy

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Michaela Turčanová ◽  
Martin Hrtoň ◽  
Petr Dvořák ◽  
Kamil Novák ◽  
Markéta Hermanová ◽  
...  
Keyword(s):  
Light Microscopy ◽  
Fiber Orientation ◽  
Collagen Fiber ◽  
Soft Tissues ◽  
Full Range ◽  
Polarized Light ◽  
Polarized Light Microscopy ◽  
Histological Image ◽  
Broad Application ◽  
Novel Method

A novel method for semiautomated assessment of directions of collagen fibers in soft tissues using histological image analysis is presented. It is based on multiple rotated images obtained via polarized light microscopy without any additional components, i.e., with just two polarizers being either perpendicular or nonperpendicular (rotated). This arrangement breaks the limitation of 90° periodicity of polarized light intensity and evaluates the in-plane fiber orientation over the whole 180° range accurately and quickly. After having verified the method, we used histological specimens of porcine Achilles tendon and aorta to validate the proposed algorithm and to lower the number of rotated images needed for evaluation. Our algorithm is capable to analyze 5·105 pixels in one micrograph in a few seconds and is thus a powerful and cheap tool promising a broad application in detection of collagen fiber distribution in soft tissues.

Preconditioning is Correlated With Altered Collagen Fiber Alignment in Ligament

2011 ◽  
Vol 133 (6) ◽  
Author(s):  
Kyle P. Quinn ◽  
Beth A. Winkelstein
Keyword(s):  
Collagen Fiber ◽  
Polarized Light ◽  
Peak Force ◽  
Principal Strain ◽  
Fiber Direction ◽  
Fiber Alignment ◽  
Tangent Stiffness ◽  
Vector Correlation ◽  
Fiber Organization ◽  
Collagen Fiber Alignment

Although the mechanical phenomena associated with preconditioning are well-established, the underlying mechanisms responsible for this behavior are still not fully understood. Using quantitative polarized light imaging, this study assessed whether preconditioning alters the collagen fiber alignment of ligament tissue, and determined whether changes in fiber organization are associated with the reduced force and stiffness observed during loading. Collagen fiber alignment maps of facet capsular ligaments (n = 8) were generated before and after 30 cycles of cyclic tensile loading, and alignment vectors were correlated between the maps to identify altered fiber organization. The change in peak force and tangent stiffness between the 1st and 30th cycle were determined from the force-displacement response, and the principal strain field of the capsular ligament after preconditioning was calculated from the fiber alignment images. The decreases in peak ligament force and tangent stiffness between the 1st and 30th cycles of preconditioning were significantly correlated (R ≥ 0.976, p < 0.0001) with the change in correlation of fiber alignment vectors between maps. Furthermore, the decrease in ligament force was correlated with a rotation of the average fiber direction toward the direction of loading (R = −0.730; p = 0.0396). Decreases in peak force during loading and changes in fiber alignment after loading were correlated (p ≤ 0.0157) with the average principal strain of the unloaded ligament after preconditioning. Through the use of a vector correlation algorithm, this study quantifies detectable changes to the internal microstructure of soft tissue produced by preconditioning and demonstrates that the reorganization of the capsular ligament’s collagen fiber network, in addition to the viscoelasticity of its components, contribute to how the mechanical properties of the tissue change during its preconditioning.

Ferroelastic domains and phase transitions in organic–inorganic hybrid perovskite CH3NH3PbBr3

2021 ◽  
Author(s):  
Maryam Bari ◽  
Alexei A. Bokov ◽  
Zuo-Guang Ye
Keyword(s):  
Phase Transitions ◽  
Electric Field ◽  
Light Microscopy ◽  
Domain Structure ◽  
Polarized Light ◽  
External Stress ◽  
Polarized Light Microscopy ◽  
Inorganic Hybrid ◽  
Hybrid Perovskite ◽  
Ferroelastic Domains

Polarized light microscopy reveals twin domains and symmetry of the phases in CH3NH3PbBr3 crystal; domain structure remains unresponsive to electric field but changes under external stress, confirming ferroelasticity while ruling out ferroelectricity.

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