150 research outputs found

    Les métastases osseuses ou le parcours du combattant

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    The fate of the quiescent surfaces of lamellar bone.

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    Microradiographic and histologic analysis of undemineralized bone was performed in 62 subjects aged 18-97 years. Ten of these samples were also submitted to scanning electron microscopy. Besides the usual lamellar bone remodeling, all types of bone surfaces, namely both haversian and vascular canals and the endosteal and trabecular surfaces, were involved in weathering alterations of the superficial lamellae, resulting in eroded outlines, less deeply notched than the Howship lacunae and devoid of osteoclast. Present as soon as early adult life and randomly distributed, these aspects were recorded in all the bone pieces examined. These observations were consistent with the hypothesis of a particular destructive process in all the quiescent lamellar bone surfaces without osteoclast participation, termed delitescence, which could be partly responsible for age-related bone loss

    Lamellar Bone Surface Delitescence

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    [Anatomical variations at the level of the muscles of the arm]

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    The muscular anatomical variations of the thoracic member are recorded in a series of 180 subjects. Two muscles are supernumerary: a bilateral accessory coraco-brachialis and a unilateral accessory palmaris longus. Two muscles have additional tendons: the extensor carpi radialis brevis and the extensor digitorum

    Postmenopausal osteoporosis: microradiographic aspects.

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    A comparative microradiographic and histologic analysis of undecalcified bone samples was performed in men and women aged 18-98 years. These morphological methods showed that besides usual lamellar bone remodelling, all the so-called inert surfaces, namely both haversian and vascular canals as well as trabecular surfaces, were involved in weathering alterations of the superficial lamellae, resulting in eroded outlines devoid of osteoclast. These aspects, recorded in all pieces of our material, were visible from the earliest adult age and were randomly distributed. Except the grade of osteoporosis at a given age, the microradiographic and histologic aspects were similar in both aged men and women and did not allow sex distinction. These observations were consistent with the hypothesis of a particular destructive process affecting all the quiescent lamellar bone surfaces without osteoclast or cell participation. This kind of erosion, termed delitescence, could be at least partially responsible for the age-related and postmenopausal bone loss. In order to explain the increasing osteoporosis after menopause, it has been suggested that the estrogen deficiency could increase the percentage of dead osteocytes. Thereby the reduced cellular control on the bone surface could impair the remodeling process and fail to adapt the bone structure by repairing the microscopic lesions

    Induced Acute-ischemia in Dog Bones - Age-related Effects

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    Microradiography and fluorescence microscopy of bone remodeling on the basal crypt of permanent mandibular premolars in dogs during eruption.

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    Alveolar bone of erupting teeth was studied in order to define the types of calcified tissues deposited as well as the rate of tooth growth. The third (P3) and fourth (P4) mandibular premolars of 30 dogs aged 12-24 weeks were analyzed by microradiography and microscopy in fluorescent and ordinary light. The bone plate separating P3 and P4 from the mandibular canal presented a complex arrangement of lamellar and woven bone, and even of chondroid tissue. During the pre-eruptive phase, this plate shifted towards the base of the mandible by means of selective resorption and apposition activities. As soon as the furcation was formed, bone apposition appeared on the alveolar side and became the main activity under P3 at the outset of eruption. Under the roots of P4 it occurred 4 weeks later. Dynamic morphometry in fluorescence microscopy showed that eruption progressed faster than the radicular growth. The formation of interradicular bone underwent the same acceleration as the eruption. However, though the tissues were formed at a high rate, it cannot be inferred therefrom that they are responsible for tooth shifting. They might just fill the space left by the erupting tooth
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