Title:
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Bone ageing and structural disconnection
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Bone is dynamic and adaptable. It has been suggested that each
region has an intrinsic hypothetical 'mechanostat' (Frost, 1987), although the
histological basis has yet to be clearly defined. To gain further insight, the
phenomenon of connection and disconnection is explored within the calcifying
protist Spirostomum ambiguum, and at three key structural hierarchical tissue
levels of the human skeleton; the cancellous bone network, the osteocyte
network and the periosteal Sharpey's fibre arrays. The tissue used was from
elderly subjects; cadaveric vertebral bodies, and femoral heads after hip
replacement for osteoporosis (OP) and osteoarthritis (OA).
Established 20 histological techniques were inappropriate for reliable
characterisation of 30 networks. In consequence, two novel methods were
developed and two unusual models adopted. These methods combined
histological techniques with image analysis, for 30 mapping and quantification
of trabecular disconnection (ReTm) in vertebral cancellous bone, and
characterisation of the osteocyte and its cytoplasmic interconnections within
the hip and spine. Model one, utilised the Ligamentum teres insertion site to
examine the fibrillar arrays of collagen III-rich Sharpey's fibres, by hard tissue
microtomy and cryomicrotomy. Model two, combined light and confocal
microscopy to observe the elements of a musculoskeletal system present
within S. ambiguum.
ReTm were heterogeneously distributed, with the caudal and cranial
regions being of interest. Sex differences were evident. Measurements of
bone 'quality' appeared independent of bone 'quantity' (R2
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