PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “HAVERSIAN SYSTEM”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2002

Three-dimensional reconstruction of Haversian systems in ovine compact bone.

Haversian systems or secondary osteons are an integral component of compact bone. However, as their exact shape is debatable, this study describes a technique to view their morphology in three dimensions. Bone remodeling in adult ovine long bones was labelled at intervals using a series of chelating fluorochromes. A series of longitudinal sections were cut at 25 microm intervals through blocks of the distal radius embedded in methylmethacrylate using a sledge macrotome. The chelating agents were used as markers of bone formation in the study of bone growth and osteon morphology. The two-dimensional image of each section was examined using an epifluorescence microscope. Images were transferred to a PC via a CCD low light colour video camera. Surface reference points were noted on each of the sections and, using computer software, a three-dimensional image of a refilling labelled osteon was reconstructed and its dimensions measured. Haversian systems may have a gentle spiral course along the longitudinal axis of the bone. They intertwine with adjacent osteons and give multiple branches along their course producing a complex pattern of organization. The mean labelled length and diameter of the osteons was 1.4 + 1 mm and 145 + 0.42 microm [Mean + S.D], respectively.

Animals↗
PubMed2006

[Comparation on Haversian system between human and animal bones by imaging analysis].

OBJECTIVE: To explore the differences in Haversian system between human and animal bones through imaging analysis and morphology description. METHODS: Thirty-five slices grinding from human being as well as dog, pig, cow and sheep bones were observed to compare their structure, then were analysed with the researchful microscope. RESULTS: Plexiform bone or oeston band was not found in human bones; There were significant differences in the shape, size, location, density of Haversian system, between human and animal bones. The amount of Haversian lamella and diameter of central canal in human were the biggest; Significant differences in the central canal diameter and total area percentage between human and animal bones were shown by imaging analysis. CONCLUSION: (1) Plexiform bone and osteon band could be the exclusive index in human bone; (2) There were significant differences in the structure of Haversian system between human and animal bones; (3) The percentage of central canals total area was valuable in species identification through imaging analysis.

Adult↗
PubMed1995

[Osteoclastic resorption of Haversian system of femoral neck cortex in aged women].

Osteoclastic resorption was studied with scanning electron microscope on cross sections of cortical bone of femoral neck collected from 7 aged women with an average age of 72.4 years, who underwent endoprosthetic replacement for intracapsular hip fracture. The cortical bone sections revealed enlargement of the Haversian canals. On the inner linings of the enlarged canals there were many oval-shaped resorption lacunae, reflecting osteoclastic resorption of the Haversian systems. The osteoclastic resorption with subsequent enlargement of the Haversian canals into round or oval cavities took place first over the inner portions of the cortical sections, thereby rendering these areas porotic (cancellization). These processes of the Haversian system and canals then gradually emerged over the central and eventually over the outer areas of the cortical bone, and the entire cortical bone became porotic. In the meanwhile, the inner porotic portion of the cortex turned into trabeculae (trabecularization) and became gradually resorbed, resulting in thinning of the medial cortex. Cortical cancellization, trabecularization and thinning so compromised the material strength of the femoral neck that fracture would ensue even with trivial injury.

Aged↗
PubMed1996

Osteoclastic resorption of Haversian systems in cortical bone of femoral neck in aged women. A scanning electron microscopic study.

OBJECTIVE: To reveal the sequence of events of osteoclastic resorption taking place in the cortical bone of the femoral neck in aged women. MATERIAL AND METHODS: The cross sections of cortical bones of the femoral neck from 7 aged women who underwent endoprosthetic replacement for intracapsular hip fracture, were processed and subjected to scanning electron microscopic observation. RESULTS: The cortical bone sections revealed enlargement of the Haversian canals. On the inner linings of the enlarged canals many oval resorption lacunae could be found, reflecting osteoclastic resorption of the Haversian systems. The osteoclastic resorption with subsequent enlargement of the Haversian canals into round or oval cavities took place first over the inner portions of the cortical sections, thereby rendering these areas porotic (cancellization). These processes of the Haversian systems and canals then gradually emerged over the central and eventually over the outer areas of the cortical bone, and the entire cortical bone became porotic. Meanwhile, the inner porotic portion of the cortex turned into trabeculae (trabecularization) and became gradually resorbed, resulting in thinning of the medial cortex. CONCLUSIONS: Cortical cancellization, trabecularization and thinning compromised the material strength of the femoral neck so that fracture would ensue even with trivial injury.

Aged↗
PubMed1980

Study of cell kinetics within evolving secondary Haversian systems.

A study of the origin, proliferation rate and migration of cells within the secondary evolving Haversian systems was undertaken in young adult Beagle dogs. Autoradiographs of serial longitudinal sections prepared from rib biopsies taken from one hour to eleven days after the injection of tritiated thymidine were subjected to semiquantitative analysis as to the time of appearance, number, location and transformation of various labelled cells. Numerous labelled osteoblasts appeared early (at 14-24 hours) in the most proximal closing cone. With time, this zone was seen to have been left behind the advancing cutting cone and the successive generations of osteoblasts. The first labelled osteocytes were seen at nine days after injection, in the distal closing cone. Labelled nuclei within the osteoclasts were few and appeared late (none before 24 hours). It is apparent that each self renewing cell population within these systems (i.e. osteoclasts, osteoblasts and endothelial cells) derives from its own immediate precursor and evolves at its own speed. The mononuclear osteoclasts' precursors divide locally and infrequently and the turnover of osteoclastic nuclei appears to be slow; consequently their life span and that of the osteoclasts appears to be longer than the time of the observation, i.e. 11 days. The proliferation of osteoblasts' precursors and osteoblasts recruitment is rapid. The life span of osteoblasts was found to be indeterminate; some osteoblasts may become osteocytes within a few days while others may continue to deposit bone for several weeks. Since the recruitment of osteoclastic nuclei is slow while that of the osteoblasts is fast, it is unlikely that the osteoclasts in the sites of lamellar bone remodelling modulate into osteoblasts.

Animals↗
PubMed1980

Changes in the vascular network during the formation of Haversian systems.

The pattern of the cortical vascular network and the changes occurring in it during the formation of Haversian systems have been studied in the diaphyses of the tibiae of dogs of various ages. The number, area, perimeter and microscopic structure of the vessels have been investigated with respect to the size of the Haversian canals and length of the osteoblastic layer, using India ink perfusion of the vascular network. The vascular network in compact bone undergoes conspicuous changes as a result of bone growth and turnover processes. The vessels proliferate during the formation of resorption cavities, eventually forming small plexuses of capillaries and tortuous venules. As osteons are laid down and their canals become more narrow, the progressive disappearance of the largest vessels leads to a reduction in the number of vessels in each canal. Morphometric analysis reveals a close correlation between the rate of osteonic bone deposition, the size of osteoblasts and the surface area of the vessels.

Animals↗
PubMed1981

Kinetics of osteoclasts and their nuclei in evolving secondary Haversian systems.

A study of osteoclast and osteoclast nuclear population kinetics within evolving secondary osteons was undertaken in young adult Beagle dogs. Autoradiographs of serial longitudinal rib biopsy sections taken from 1 hour to 15 days after tritiated thymidine injection were analysed as to the time and the rate of appearance of the labelled nuclei within the osteoclasts and their nuclei. Such systems contained an average of nine osteoclasts, each containing an average of nine nuclei. Labelled osteoclast nuclei first appeared within 24 hours, peaked at 10% at 4 days, and declined to 1% or less after 11.5 days more. Thus, the entry rate of new nuclei into (and their exit from) the population of osteoclast nuclei under steady state conditions approximates 8% per day. Therefore, the total mononuclear osteoclast population may be viewed as divided into functional units, i.e. osteoclasts. From the ratio of the osteoclast nuclei in the cutting cone to the number of osteoblasts in the closing cone (as well as from their rates of resorption and formation), it was deduced that the osteoclast per nucleus is approximately 20-40 times more efficient than the osteoblast. Because of the intrinsically different efficiencies and life spans of these two cell types, the rates of resorption and formation within evolving Haversian systems and the amounts of bone ultimately resorbed and formed by the system, are determined by the rate and duration of the respective precursor cell proliferation. It is at this level that factors which control the bone remodelling and balance must operate.

Animals↗
PubMed1994

Long-term changes in the haversian systems following high-dose irradiation. An ultrastructural and quantitative histomorphological study.

The effects of high-dose irradiation on the morphology of haversian bone were studied, over a fifty-two-week period, in seventy-seven adult rabbits, after the administration of a single dose of radiation (therapeutic x-ray; twenty-five, fifty, or 100 gray) to one knee joint. The specimens of bone were examined with microangiography, light and transmission electron microscopy, and histomorphometry. Analysis was performed on the haversian bone in the subchondral bone plate of weight-bearing portions of the femoral condyles. Microangiography demonstrated dilatation of the microvasculature four weeks after irradiation. Beginning at twelve weeks, there was a marked decrease in vascularity; no obvious recovery of the subchondral bone had occurred by fifty-two weeks. At four weeks, morphological analysis revealed two changes in the haversian canals: simple occlusion of the haversian vessels with loss of cells in the canal, and dilatation of the capillaries with abnormal resorption of the perivascular bone matrix by osteoclasts. The abnormal bone resorption was not coupled with subsequent new-bone formation, resulting in increased porosity. Beginning at four weeks, a progressive decrease in the number of haversian vessels and in cellularity became prominent. The decrease in cellularity involved all types of cells, including endothelial cells, pericytes, perivascular mesenchymal cells, osteoblasts, osteocytes, and osteoclasts. The loss of perivascular cells was often but not always associated with occlusion of the haversian vessels. Histomorphometry revealed both time-dependent and dose-dependent decreases in capillary density (the number of intraosseous capillaries per unit area) and in the number of osteocytes in the subchondral bone plate. The porosity of the same areas showed a significant increase by four weeks (p < 0.001 after administration of twenty-five gray and p < 0.01 after administration of both fifty and 100 gray), but between twelve and fifty-two weeks, there was only a slight additional increase. Statistical analysis revealed significant correlations between capillary density and osteocyte survival (p < 0.001) and between capillary density and porosity (p < 0.001). The portion of the subchondral bone plate that was located farthest from the non-irradiated normal bone showed progressive damage and no sign of recovery at fifty-two weeks.

Animals↗
PubMed1983

Primary calcification in remodeling haversian systems following tibial fracture in rats.

Electron micrographs of fracture callus obtained ten days after injury show typical primary matrix vesicle mineralization. In remodeling haversian canals distant from the fracture sites, matrix vesicles and calcifying nodules were observed. The occurrence of these elements was also found to control unfractured tibiae with intramedullary nails but not normal bone. These observations suggest that during haversian remodeling, mineralization after osseous or marrow tissue damage is associated with matrix vesicles.

Animals↗