1 July 2008 Collagen fiber arrangement in normal and diseased cartilage studied by polarization sensitive nonlinear microscopy
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J. of Biomedical Optics, 13(4), 044020 (2008). doi:10.1117/1.2950318
Abstract
Second harmonic generation (SHG) and two-photon fluorescence (TPF) microscopy is used to image the intercellular and pericellular matrix in normal and degenerate equine articular cartilage. The polarization sensitivity of SHG can be used directly to determine fiber orientation in the superficial 10 to 20 μm of tissue, and images of the ratio of intensities taken with two orthogonal polarization states reveal small scale variations in the collagen fiber organization that have not previously been reported. The signal from greater depths is influenced by the birefringence and biattenuance of the overlying tissue. An assessment of these effects is developed, based on the analysis of changes in TPF polarization with depth, and the approach is validated in tendon where composition is independent of depth. The analysis places an upper bound on the biattenuance of tendon of 2.65×10-4. Normal cartilage reveals a consistent pattern of variation in fibril orientation with depth. In lesions, the pattern is severely disrupted and there are changes in the pericellular matrix, even at the periphery where the tissue appears microscopically normal. Quantification of polarization sensitivity changes with depth in cartilage will require detailed numerical models, but in the meantime, multiphoton microscopy provides sensitive indications of matrix changes in cartilage degeneration.
Jessica C. Mansfield, C. Peter Winlove, Julian J. Moger, Stephen J. Matcher, "Collagen fiber arrangement in normal and diseased cartilage studied by polarization sensitive nonlinear microscopy," Journal of Biomedical Optics 13(4), 044020 (1 July 2008). http://dx.doi.org/10.1117/1.2950318
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KEYWORDS
Polarization

Cartilage

Collagen

Second-harmonic generation

Tissues

Birefringence

Natural surfaces

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