The three dimensional microstructural network of elastin, collagen and cells in Achilles tendons

Similar to most biological tissues, the biomechanical and functional characteristics of the Achilles tendon are closely related to its composition and microstructure. It is commonly reported that type I collagen is the predominant component of tendons and is mainly responsible for the tissue's function. Although elastin has been found in varying proportions in other connective tissues, previous studies report that tendons contain very small quantities of elastin. However, the morphology of and the microstructural relationship among the elastic fibres, collagen and cells in tendon tissue have not been well examined. We hypothesize the elastic fibres, as another fibrillar component in the extracellular matrix, have a unique role in mechanical functions and microstructural arrangement in Achilles tendons. Using confocal and Second Harmonic Generation (SHG) imaging techniques, this study examined the 3-dimensional microstructure of the collagen, elastin and cells in the mid-portion of hydrated rabbit Achilles tendons. It has been shown that elastic fibres present a close connection with the tenocytes. The close relationship of the three components has been revealed as a distinct, integrated and complex microstructural network. Notably, a "spiral" structure within fibril bundles in Achilles tendons was observed in some samples in specialized regions. This study substantiates the hierarchical system of the spatial microstructure of tendon, including the mapping of collagen, elastin and tenocytes, with 3-dimensional confocal images

Rotated hough filtering for automatically distinguishing the collagen bundles in the most superficial layer of articular cartilage

The structure of the collagen matrix in the most superficial layer of articular cartilage (AC) is particularly critical to the wear and tensile resistance of AC. Disruption of the collagen network leads to rapid wear of the articular surface, which is a major contributory factor of osteoarthritis. Interwoven fiber bundles have been observed in the most superficial layer of healthy AC under confocal microscopy, but gradually disappear with age and pathological change of AC. The image analysis techniques developed in this paper aimed to provide a quantitative description of the relationship between the presence of the fiber bundles in the lamina splendens and health status of AC. The result of this quantitative study confirmed the existence of fiber bundles in healthy AC, and the accuracy of the identified fiber bundles was up to 90%. With the development of confocal arthroscopy for imaging microstructure of AC without biopsy, the image analysis technique can aidto efficiently assess the physiological status of AC for orthopaedic clinics

Characterising pattern asymmetry in pigmented skin lesions

Abstract. In clinical diagnosis of pigmented skin lesions asymmetric pigmentation is often indicative of melanoma. This paper describes a method and measures for characterizing lesion symmetry. The estimate of mirror symmetry is computed first for a number of axes at different degrees of rotation with respect to the lesion centre. The statistics of these estimates are the used to assess the overall symmetry. The method is applied to three different lesion representations showing the overall pigmentation, the pigmentation pattern, and the pattern of dermal melanin. The best measure is a 100% sensitive and 96% specific indicator of melanoma on a test set of 33 lesions, with a separate training set consisting of 66 lesions