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At least 163 records · Page 9Linked to original sources
PubMed1977

Remodeling of compact bone studied with lead acetate as an intravital stain.

Remodeling of the osteons or Haversian canal system in compact bone was studied in young monkeys that received serial injections of lead acetate as an intravital strain. The successive stages of the formation of an osteon have been demonstrated. The rate of the filling of the lamellar bone decelerated as the lumen of the Haversian canal decreased. The total formation time of individual osteons was estimated.

Acetates↗
PubMed1991

[The construction principle of bone. II. Microstructure].

On the basis of the ultrastructure of the Haversian lamellar system of bones analyses from the biomechanical viewpoint were undertaken. Instead of computed results preference was given to comparisons with tubes, fibres and nets so as to demonstrate clearly the building principle and movement phenomena. From the course of the collagenous fibres the tensile strains could be discerned which facilitated to determine also the direction of the compressive strains. The mineral components of the bone tissue are oriented toward the direction of the compressive strains. The construction principle of the lamella, however, facilitates reversible deformations and thus regeneration processes which distinguishes it from other technical building principles.

Animals↗
PubMed1997

Patterns of femoral bone remodeling dynamics in a Medieval Nubian population.

The relationship between age, sex and histomorphometry in femoral cortical bone was examined in a skeletal population of late Medieval antiquity (AD 1250-1450) from Kulubnarti, in Sudanese Nubia. These skeletal remains are naturally mummified and in an excellent state of preservation. The study sample consisted of femoral cross sections from 24 females and 19 males ranging in age from 20 to 50+ years. Femoral cross sections were examined using an image analysis system. Numbers of secondary osteons and osteon fragments were counted, osteon area and Haversian canal area were measured, and several variables were calculated to assess differences between sexes and among age groups in bone remodeling variables. The results indicate significant differences between the sexes in osteon number and size. Males had significantly more intact osteons than females, whereas females had significantly larger osteons than males. Haversian canal dimensions were not statistically significant between the sexes. Sex differences in activity patterns in which males were involved in more physically strenuous tasks may have contributed to differences in remodeling variables. Interpopulational comparisons suggest that mechanical strain affects the microstructural features examined in this study. In particular, small Haversian canals in some archaeological skeletal populations are associated with higher bone volume, which may result from high levels of mechanical strain.

Adult↗
PubMed1990

Fluid-path in the mandible and maxilla.

We examined fluid-paths in the maxilla and mandible of the dog, and compared them with Kihara's extravascular fluid-path-system. Areolar tissue is formed in the walls of the Volkmann's and Haversian canals. This tissue is composed of collagenous and reticular fibers. Kihara confirmed the collagenous fibers were encircled, however we could not ascertain whether they were encircled or not. We have compared the paths in the walls of the Volkmann's and Haversian canals with Kihara's fluid paths, and found the paths in the bone do not belong to the category of Kihara's paths. Namely, the term "extravascular fluid path" should not be applied to the areolar tissue in the bone. We suggest the term "fluid path" for this tissue in the bone. The areolar tissue in the walls of the Volkmann's and Haversian canals and endosteum communicate with one another. We call them collectively endosteum. Yoshikawa called the areolar tissue in the Volkmann's and Haversian canals perivasculäre lymsphräume. However, this designation is inadequate considering the actual characteristics of this tissue.

Animals↗
PubMed1980

Pattern of age related bone loss in mandibles.

A study was carried out to analyze the pattern of the age related bone loss in the mandibular cortex and to establish normal values and the observed range of morphometric variables on microradiograms of bone sections taken from a well defined site anterior to and below the mental foramen. Specimens were obtained from 100 Danish subjects with no known systemic bone disease or severe mandibular atrophy. Microradiograms of 100-micron-thin undemineralized vertical ground cross-sections were produced. An electric point-counting system was used for the determination of 1) percentage bone mass, 2) mean cortical width (MCW), and 3) the percentage of Haversian canals with resorption surfaces. The analysis showed that cortical porosity and the percentage of Haversian canals showing resorption are unrelated to sex and increased after the age of 50. MCW and absolute bone mass (MCW x % bone mass) are greater in males than in females and show a parallel age related decrease after the age of 50. Furthermore, the age related increase in cortical thinning and porosity is dependent on the individual as well as on age. Marked individual variation confined the use of these parameters to group analysis.

Adult↗
PubMed1984

The effects of remodeling on the elastic properties of bone.

Cortical bone can be modeled as a complex hierarchical composite interrelating both structure and material properties on four levels of structural organization: molecular, ultrastructural, microscopic, and macroscopic. In young animals, the microstructural systems are long parallel lamellar units, plexiform bone, which in older or more mature animals converts by internal remodeling into multiple concentric lamellar units, secondary osteons, forming haversian bone. Ultrasonic wave propagation measurements performed on both plexiform and haversian bone clearly show a definitive relationship with microstructure; haversian bone can be described as a transversely symmetric material whereas plexiform bone appears to be orthotropic in nature. The anisotropy of the elastic constants are found to reflect the tissue symmetry; moreover, plexiform bone is stiffer and more rigid in all directions than is haversian bone. Similar experiments were performed on osteoporotic and osteopetrotic bone. While the results for osteoporotic bone are understandable in terms of the increased porosity, the results for the osteopetrotic bone are anomalous with respect to its density. Since Wolff, the remodeling of bone has been interpreted as a way of altering the mechanical properties to suit some need. For haversian remodeling from plexiform bone, the argument that adaptation occurs to optimize properties requires additional clarification since haversian bone appears to have inferior mechanical properties to plexiform bone.

Animals↗
PubMed1992

[The diameters of the central canals of the osteons in tubular bones (based on data from scanning electron microscopy and centrifugal porosimetry)].

The centrifugal poremetry is based on preliminary filling the pores of prepared samples with the working fluid and the following removal of it from the pores at different fixed velocities of rotation. Measurement of the quantity of the remaining fluid after each rotation allows obtaining the distribution of the pore volume depending on their radius. Since the samples are not destroyed they can be used for measuring the pores diameter in electron micrograph. Comparison has been made of the distribution of the pores quantity by their diameters obtained by morphometry with the distribution of the pores volume by their diameters obtained by differentiation of poremetry curves. Besides greater detailization of the prevailing diameters of the pores, the method of poremetry allows the information to be obtained concerning the distribution of not only sizes of central canals of osteons but also smaller pores characterizing the system of lacunae of osteocytes and canals connecting them.

Adult↗
PubMed1982

Microradiographic and histomorphometric indices of mandibles for diagnosis of osteopenia.

Mandibular autopsy specimens of 100 Danish subjects without known systemic diseases were obtained. Microradiograms of 100-micrometer-thick undemineralized vertical buccolingual grounds cross-sections and these sections, stained with basic fuchsin, were used. Microradiographic and histologic readings of bone turnover foci on Haversian canal and endosteal-trabecular surfaces were compared and combined. The analyses show the following. 1) number/area Haversian canals with bone formation and resorption foci and total of Haversian canals are reproducible and representative measures for bone turnover, while estimation of % bone turnover surfaces on periosteal and endosteal-trabecular surfaces in biopsies of mandibles has no diagnostic value. 2) Percentage of bone mass and mean cortical width in standard locality indicate the level in group of mandibles. 3) the cortical variables of bone turnover are sex independent; number/area Haversian canals with resorption foci is age independent; number/area Haversian canals with bone formation foci, total of Haversian canals and percentage of subendosteal (Haversian canals + marrow spaces) are increased with age.

Adult↗
PubMed1987

Effect of prostaglandin E1 on regional haversian remodeling in beagles with fractured ribs: a histomorphometric study.

A histomorphometric study was carried out on healing defects in the ribs of beagles. A transverse fracture was made surgically in the midshaft of the left 9th and 10th ribs. Ten beagles received injections of either a buffer vehicle (n = 4) or prostaglandin E1 (PGE1) at a dose of 0.4 mg/day locally (n = 6) into the fracture sites for a 10-day period and were killed 30 days after the surgery. Double-pulsed fluorescent labels were given with each of two fluochrome markers, calcein before surgical treatment and oxytetracycline hydrochloride before killing. The objectives were to determine manifestations of the regional acceleratory phenomenon (RAP) as changes in regional remodeling in the haversian envelope induced by fracture, effects of PGE1 on modification of the RAP in the haversian envelope, and systemic effects of PGE1 on remodeling changes of the contralateral matching sites. The differences in haversian remodeling between the injured and uninjured ribs of the experimental dogs indicated an increase in activation frequency, that is, regional acceleratory phenomenon. The significant effect of PGE1 on enhancing fracture-induced acceleration of haversian remodeling was doubtful, because of the preexistent biologic differences found in the two experimental groups. Nevertheless, the two groups shared a similar pattern of remodeling activity. The posttraumatic mineralization that declined at the sampled sites need further investigation.

Alprostadil↗