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PubMed1984

The cellular basis of bone remodeling: the quantum concept reexamined in light of recent advances in the cell biology of bone.

The cellular basis of the normal bone remodeling sequence in the human adult is discussed in relation to a cycle of five stages--quiescence, activation, resorption, reversal, formation, and return to quiescence. Normally, 80% or more of free bone surfaces are quiescent with respect to remodeling. The structure of the quiescent surface comprises 5 layers; listed in order out toward the bone marrow these are: the lamina limitans (the electron dense outer edge of the mineralized bone matrix), unmineralized connective tissue that may be confused with osteoid by light microscopy, flattened lining cells of osteoblast lineage separated by narrow gaps, more unmineralized connective tissue, and finally either the squamous sac cells of red marrow or the cytoplasm of fat cells of yellow marrow. Activation requires the recruitment of new osteoclasts derived from precursor cells of the mononuclear phagocyte system (and so ultimately from the hematopoietic stem cell), a method for precursor cells to penetrate the cellular and connective tissue barrier of the quiescent surface, and so gain access to the bone mineral, and mechanisms for their attraction and binding to the mineralized surface, possibly in response to chemotactic signals released from bone matrix or mineral. Each of these three steps is probably mediated in some way by lining cells. Resorption is carried out by osteoclasts, most of which are multinucleated. The mean life span of individual nuclei is about 12.5 days; the additional nuclei needed to sustain resorption may be derived from local as well as blood-bone precursors, but nothing is known of their fate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗
PubMed1995

Experimental transplantation of hydroxylapatite-bone composite grafts.

PURPOSE: This study was undertaken to determine if autogenous bone can be cultivated in vivo in a porous hydroxylapatite (HA) matrix by ingrowth from underlying bone and if this autogenous HA-bone composite graft can then be transplanted. PATIENTS AND METHODS: Five Göttingen minipigs received subperiosteal implantation of one HA block each (40 x 10 x 10 mm), covered by a polylactic membrane, on the ascending ramus of the mandible. After 5 months, half of each implant was harvested and transplanted as an onlay graft to the horizontal ramus of the mandible with simultaneous insertion of a titanium implant. Polychrome fluorescence labeling was done 1, 2, 4, and 8 weeks postoperatively. After 3 months, the vascular system of the animals was filled with BaSO4 for microangiographic examination, and all blocks were retrieved. RESULTS: Fluorescence microscopy showed that there was a significant decrease in deposition of the label in the grafted blocks at 1 week when compared with later labels. After the second week, there were no significant changes. A 20% to 30% decrease in the frequency of fluorochrome staining was noted in the upper third of each block. In this region, microangiography demonstrated highly vascularized tissue and limited bone resorption. CONCLUSION: It was concluded that cultivation of mandibular bone in a porous matrix under guided bone regeneration is possible and that this autogenous HA-bone composite graft can be transplanted at a later date.

Angiography↗
PubMed1985

Metabolic pathways of the fossil dinosaur bones. Part V. Morphological differentiation of osteocyte lacunae and bone canaliculi and their significance in the system of extracellular communication.

The study was carried out on dinosaur bones nearly 80 million years old. Samples for examination were prepared with specially elaborated methods. The light and transmission electron microscopic images permitted two kinds of bone lacunae and two types of paralacunar canalicular endings to be distinguished. The lacunae of the first kind were characterized by their elongated shape, their length exceeding their width several times, their dimensions being 31.2/9.4 microns. The lacunae of the other kind were not so long, their mean measurements amounting to 21.32/9.7 microns. Among the paralacunar canalicular endings those of small diameter were more numerous. The canaliculi of wider, funnel-shaped endings amounted to two or three, they were usually localized in the polar part of the lacuna, and were defined as the axial canaliculi. These were canaliculi of a large diameter. The canalicular wall was constructed of collagen fibres. The same fibres were found in the lacunar wall. Also a relationship between the structure of the lacunar wall and the localization of an osteocyte in the lacuna was analysed in the light and electron microscopes. In regard to the structure of the bone lacuna and the localization of an osteocyte in it, zones A and B were distinguished. Zone A had a characteristic loose and disorderly system of collagen fibres building the lacunar wall. The fibres in this area were by nature open to view. Besides, this region of the lacunar wall revealed specific terraced hollows. Zone B was distinguished by a compact system of parallelly arranged collagen fibres, which formed characteristic ridges in the lacunar wall. The localization of the osteocyte in the lacuna was irregular, the pericellular space around it being of variable width. This space was shown to contain mucopolysaccharides. The images obtained from dinosaur bone were compared with those already known for modern bone. These comparisons permitted it to be ascertained that zone A corresponds to a spot in the lacuna in which the osteocyte exhibits a decreased activity. Zone B is the area of the actual direction of the osteocyte's activity aiming at the shaping of the wall of its lacuna. It can be supposed that the widened endings of the paralacunar canaliculi perform more important functions in conveyance, this being evident from comparisons of analogous areas in modern bone.

Animals↗
PubMed1995

Onlay silicone and hydroxyapatite-tricalciumphosphate composite (HAP-TCP) blocks interfere with nasal bone growth in rabbits.

We investigated how a new type of synthetic porous hydroxyapatite ceramic (HAP-TCP) acts when it is implanted in growing membranous bone. Seventy-six New Zealand White infant male rabbits (4-week-olds) were used. Rabbits received HAP-TCP block or silicone block implantation in their right nasal bone. The left nasal bone was used for a sham. Serial or cross-sectional examinations by morphometry, radiology, blood biochemistry, and histology were carried out. Both the HAP-TCP and silicone groups exhibited no systemic growth disturbance in terms of morphometry and blood biochemistry. Dual energy x-ray absorptiometry (DEXA) revealed, however, a decrease in the bone mineral content (BMC) of the right nasal bone in the silicone group. Histology revealed a superior affinity of HAP-TCP to bone tissue than that of silicone. When a HAP-TCP block was implanted under the periosteum it bonded directly to bone tissue. However, sinking of the implants into the bone tissue were noted both in the HAP-TCP and the silicone groups in longitudinal observation. These results suggest that although HAP-TCP has superior affinity to bone tissue, this by itself is not enough sufficient reason to believe that HAP-TCP can be effectively applied during the growth period.

Absorptiometry, Photon↗
PubMed2003

Micromechanics/structure relationships in the human mandible.

OBJECTIVES: A clear understanding of the relationship between the micromechanical properties and orientation of the osteons within the mandible is important to understand mandibular function, fracture repair, treatment of temporo-mandibular joint disorders, the materials and organization of dental implants. The objective of this research was to obtain the micromechanical properties of human mandibular cortical bone as a function of orientation from TMJ to TMJ. METHODS: A mandible obtained from a deceased 66 year-old female free of bone disease was used. The mandible was embedded in polymethylmethacrylate. The micromechanical properties analysis was obtained using the UH3 scanning acoustic microscope (SAM; Olympus Co., Tokyo, Japan). The coordinates system is defined such that the inferior border of mandibular is positioned on the x-y plane. x is along the anterior-posterior direction, y is in the horizontal direction and z is in superior-inferior direction. RESULTS: The osteonal orientations were almost parallel to the x axis and eventually branched into two directions towards the coronoid process and condylar head. The SAM revealed that almost the whole area of the mandible body was found to be transversely isotropic in the plane perpendicular to the x axis. In the parallel and oblique directions, all data were transversely isotropic with respect to the x axis. Data of the perpendicular osteons were transversely isotropic with respect to the z axis. SIGNIFICANCE: Having actual micromechanical properties as a function of orientation in the mandible could provide base line data for: fracture repair; choice of bone replacement materials.

Aged↗
PubMed2003

Liquid crystalline assemblies of collagen in bone and in vitro systems.

Precise descriptions of the three-dimensional arrangements of collagen in bone are essential to understand the mechanical properties of this complex tissue. Transmission electron microscopy (TEM) analysis of decalcified human compact bone in section reveals characteristic patterns forming regular series of nested arcs. Such patterns are a direct consequence of an organization described as a twisted plywood and relate the distribution of collagen fibrils in osteons with that of molecules in cholesteric liquid crystals. The hypothesis that liquid crystalline properties are involved in the morphogenesis of dense collagen matrices was supported by data obtained in vitro. At a molecular level, acid-soluble collagen molecules spontaneously assemble, at concentrations of 50mg/ml or more, in precholesteric-banded patterns and cholesteric phases, identified by polarized light microscopy. In a more physiological context, these results were conforted, with the precursor molecule of collagen, procollagen, soluble at neutral pH. This protein spontaneously forms liquid crystalline precholesteric phases corresponding to banded patterns and birefringent cords. Stabilization of the liquid crystalline collagen, induced by pH modification and fibril formation, shows characteristic morphologies in TEM, which directly mimic arrays described in vivo. Undulating fibrils are indeed similar to crimp morphologies described in tendons and continuously twisting fibrils, and give rise to arced patterns similar to supra-molecular architectures identified in compact bone.

Biomechanical Phenomena↗
PubMed2004

Structure of long bones in mammals.

Techniques for staining (silver, osmium, metal sulfides, ink) and microphotography (epi-illumination) of polished bone surfaces have been developed to visualize the three-dimensional structure of the shafts of mammalian long bones. Bone is a two-compartment system with capillaries and some kinds of connective tissue in one compartment separated from fibers of bone collagen, often forming lamellae, in the other. Laminar bone consists of stacks of lamellae separated by vascular spaces containing capillary network sheets. It is deposited at the periosteal and endosteal surfaces. Osteonic bone, well described in the literature, consists of cylinders of lamellae with central vascular spaces. The primary structure of the shafts of mammalian long bones is laminar and laminae often remain as the main component. Secondary osteons are a replacement within laminae. As laminar bones mature, some of the irregular longitudinal capillary spaces in the network sheets enlarge and become less crooked to form secondary osteons. Parts of the random networks become ordered longitudinal ones, resulting in collapse of those network spaces not converted to osteons. The residual capillaries become bloodless, making the surviving network spaces difficult to resolve. This may account for them being overlooked in descriptions of bone structure. For example, laminar bone occurs with osteonic bone in the human femur, although it is rarely figured. Nearly mature bones switch the kind of primary bone deposited at the peripheral (periosteal) surface from laminar to primary osteonic.

Animals↗
PubMed1995

Relationships between endothelial cells, pericytes, and osteoblasts during bone formation in the sheep femur following implantation of tricalciumphosphate-ceramic.

BACKGROUND: The origin of osteoblasts is still controversial. Whereas several authors consider the stromal fibroblast of the bone marrow as the osteoprogenitor cell, others propose that the osteoblasts can be derived from the "capillary system." The present study examines the replacement of tricalciumphosphate (TCP)-ceramic implanted into an artificial bone defect by newly formed bone. The results support the hypothesis that osteogenic cells can be derived from invading blood vessels. METHODS: The spongiosa of the trochanter major of sheep was removed and the defect was filled with TCP-ceramic. Two months after surgery the ceramic implants together with the surrounding bone were removed and processed for transmission electron microscopy. Serial ultrathin sections of three newly formed osteons were examined. RESULTS: The osteons contain one or two small sprouting capillaries, a peripheral layer of osteoblasts, and in between, a network of glycogen-rich cells. Some of the glycogen-rich cells are completely or partly surrounded by the endothelial basal lamina and are thereby characterized as pericytes. Weibel-Palade bodies, which are considered to be a marker of endothelial cells, were occasionally observed in glycogen-rich pericytes. CONCLUSIONS: Since pericytes differentiate into osteoblasts under in vivo and in vitro conditions, and have thus been regarded as osteoprogenitor cells, the presence of Weibel-Palade bodies in these cells suggest that osteogenic cells can be derived from endothelial cells.

Animals↗
PubMed2002

The role of interstitial fluid flow in the remodeling response to fatigue loading.

Load-induced fluid flow enhances molecular transport through bone tissue and relates to areas of bone resorption and apposition. Remodeling activity is highly coordinated and necessitates a means for cellular communication via intracellular and extracellular means. Osteocytes, osteoblasts, and osteoclasts, which reside in disparate locations within the tissue, communicate intracellularly via the cellular syncytium and extracellularly via the pericellular fluid space of the lacunocanalicular system. Both of these communications systems are physically disrupted by microdamage incurred during fatigue loading of bone. The purpose of this study was to develop an analytical model to understand the role of interstitial fluid flow in the remodeling response to fatigue loading. Adequate transport was assumed a prerequisite for maintenance of cell viability in bone. Diffusive and convective transport were simulated through the lacunocanalicular network in a healthy undamaged state as well as in a damaged state after fatigue loading. The model predicts that fatigue damage impedes transport from the blood supply, depleting the concentration of molecular entities in and downstream from areas of damage. Furthermore, the presence of microcracks alters the distribution of molecular entities between individual lacunae. These effects were confirmed by the results of an in vivo pilot study in which fluorescent, flow-visualizing agents pooled within microcracks and were absent from areas surrounding microcracks, corresponding to areas deprived of fluid flow. Loss of osteocyte viability is coupled to targeting and initiation of new remodeling activity. Taken as a whole, these data suggest a link between interstitial fluid flow, mass transport, maintenance of osteocyte viability, and modulation of remodeling activity.

Biological Transport↗
PubMed2006

Peri-implant bone organization under immediate loading state. Circularly polarized light analyses: a minipig study.

BACKGROUND: Immediate loading of dental implants is currently one of the most examined topics in implant dentistry. Using screw implants with a microstructured surface and bone-quality-adapted insertion procedures, osseointegration is achieved when implants are initially stable and when splinted with the superstructure. Despite reported success, there is a shortage of information relating to remodeling and peri-implant bone formation with immediately loaded implants. METHODS: Four to six immediately loaded and unloaded dental implants with a microstructured surface were placed in the mandible and the maxilla in seven minipigs. A total of 85 implants were placed. After a 4-month healing period, all implants were retrieved. Histomorphometry was performed using a light microscope in transmitted polarized light connected to a high-resolution video camera interfaced to a monitor and personal computer. This optical system was associated with a digitizing pad and a histomorphometry software package with image capturing capabilities. RESULTS: Implants showed osseointegration if the average insertion torque of the implants within one bridge was >35 Ncm. If the primary stability of the bridge was <35 Ncm, all implants in the quadrant were lost after 4 months. The multivariate discriminant analysis showed the highest correlation for implant stability by bridge insertion torque (BIT), localization (mandible or maxilla), and implant insertion torque (IIT) as success parameters. The loaded implants displayed collagen fibers, which were oriented in a more transverse way. In addition, a higher quantity of secondary osteons was present. In comparison, the unloaded implants had collagen fibers with a more parallel orientation, and a higher quantity of marrow spaces was present. CONCLUSIONS: When observed after 4 months, immediately loaded implants showed a higher degree of bone formation and remodeling in comparison to unloaded implants. Immediately loaded implants also demonstrated a prevalence of transversely oriented collagen fibers in the peri-implant bone. In this animal model, an average insertion torque of the implants within one bridge>35 Ncm was associated with the most successful implants.

Animals↗
PubMed2000

A novel mechanism for induction of increased cortical porosity in cases of intracapsular hip fracture.

It has been suggested that, in hip fracture, the cortex on the inferoanterior (IA) to superoposterior (SP) axis is thinned and shows increased porosity. This is dependent on the presence of giant canals (i.e., diameter >385 microm), which are related to clusters of remodeling osteons. To investigate further the relationship between remodeling and bone loss, osteonal diameter (On.Dm), wall thickness (W.Th), osteoid width (O.Wi), and extent (OS) were measured in femoral neck biopsies from 12 female intracapsular hip fracture cases and 11 age- and gender-matched controls. Over 83% of giant canals were "composite" osteonal systems in which a single canal was surrounded by multiple packets of osteonal bone. Among smaller canals, over 80% of systems had a canal encircled by a single cement line containing one packet of bone ("simple"). Composites were nearly twice as prevalent in fractures (fracture cases 9.8 +/- 0.7/25 mm(2), controls 5.3 +/- 0.4/25 mm(2), p < 0. 0001), and were dependent (R(2) = 0.52) on femoral neck region (p = 0.0008) and the regional distribution of clusters of remodeling osteons (p = 0.0045). Both the inferior (I) and anterior (A) regions had an elevated number of composites (I: 263% of control values, p = 0.0054; A: 202% of control values, p = 0.0092). On.Dm was similar in fracture cases and controls (simple: fracture cases 183 +/- 3 microm, controls 191 +/- 4 microm; composites: fracture cases 446 +/- 13 microm, controls 460 +/- 13 microm). W.Th in simples was similar in fracture cases and controls (fracture cases 51 +/- 0.8 microm, controls 49 +/- 0.7 microm), but composites had significantly (p < 0. 0001) thinner walls, with the reduction in fracture cases (31%) being twice that of controls (12%, p < 0.0001). There were no differences in O.Wi. It was unusual for osteoid to fully surround the composite canal surface; OS was 38% lower in composite than simple canals (p < 0.0001). This study indicates that, in the femoral neck cortex, the principal remodeling deficit in hip fracture is specific to composite osteons. Hip fracture cases had zonal increases in composite osteon density with reduced bone formation. The data suggest that generation of composite osteons is a plausible mechanism leading to increasing porosity and trabecularization of the cortex, thus weakening the cortex in regions maximally loaded on fall impact.

Aged↗
PubMed1976

The actions of parathyroid hormone on bone: relation to bone remodeling and turnover, calcium homeostasis, and metabolic bone disease. Part I of IV parts: mechanisms of calcium transfer between blood and bone and their cellular basis: morphological and kinetic approaches to bone turnover.

The supracellular organization of living bone enables the study of isolated cellular and subcellular systems to be related to the study of the whole organism. Bone is formed by osteoblasts in successive stages, separated in both time and space, of matrix formation and primary mineralization. Osteoblasts are joined by tight junctions and largely cover the osteoid seam which separates them from mineralized bone. Secondary mineralization is not completed for several months and is not regulated by the osteoblast. Bone is resorbed by osteoclasts which simultaneously accomplish mineral dissolution and matrix digestion. Active osteoblasts occupy about 5% of the free bone surface, osteoid seams with less active osteoblasts about 10%, active osteoclasts about 0.5%, and Howship's lacunae at which bone remodeling is either quiescent or arrested about 5%. The remaining 80% of the free bone surface is covered by a leaky envelope of thin flattened cells, termed surface osteocytes. Some osteoblasts become permanently buried in the bone as deep osteocytes, around which a specialized and metabolically active perilacunar bone is formed. This bone is less highly mineralized and can temporarily lose or gain calcium in accordance with homeostatic needs. Deep osteocytes maintain contact with each other and with the surface osteocytes, their cell processes within canaliculi being joined by gap junctions. Remodeling of cortical bone proceeds with the excavation by osteoclasts of a longitudinal tunnel which is refilled by osteoblasts to form a new osteon. The anatomically discrete longitudinally oriented structure consisting of a cutting cone of osteoclasts in front and a closing cone of osteoblasts behind is termed a cortical remodeling unit. The events of centrifugal resorption and centripetal formation which occur in a single cross section is termed a cortical remodeling cycle. Normally each new cycle is slightly out of phase with its predecessor. The quantities which characterize cortical remodeling are the birth rate of new remodeling cycles or activation frequency (mu), and the durations of the resorptive period (sigma r), the quiescent interval (sigma q) and the formation period (sigma f). The average distances traveled by the osteoclast and osteoblast are indicated respectively by the mean cement line diameter and mean wall thickness of completed osteons. These quantities show little interindividual variation. Because of this constancy the magnitude of bone turnover (the bone formation rate) is almost entirely a function of mu, the activation frequency of new remodeling cycles. Variations in the velocity of advance of osteoclasts (the linear resorption rate) or of osteoblasts (the appositional rate) alter inversely both the extent of surface engaged in resorption or formation and the time taken to replace a particular moiety of bone, but in a steady state do not influence the rate of turnover of the skeleton as a whole...

Animals↗
PubMed1993

Experimental mandibular regrowth by distraction osteogenesis. Long-term results.

The use of gradual distraction to grow bone (distraction osteogenesis) has gained widespread orthopedic acceptance, but has only recently been applied to craniofacial skeletal defects. The use of bifocal distraction osteogenesis to fill experimental segmental mandibular defects with regenerate bone was recently reported. Though all canines in that study demonstrated normal oromandibular function, they were observed for only 4 weeks following defect closure. The study that is now reported describes the long-term (12-month) functional, morphologic, and biomechanical results when bifocal distraction osteogenesis was applied to the same model. In this long-term study, three canines had 2.5-cm unilateral segmental mandibular body defects filled with structurally stable bone using bifocal distraction osteogenesis. These dogs exhibited normal oromandibular function for 1 year following segment regrowth and external fixator removal. Macroscopic and histologic evaluation of the regrown segments revealed a re-formation of the cortical and medullary architecture. Stress testing demonstrated the average ultimate strength of the regrown segment at 53 MPa, which corresponded to 77% +/- 5.7% of normal mandibular bone. The data suggest that clinical trials applying this technique to segmental mandibular reconstruction are warranted.

Animals↗
PubMed1998

Variability in osteon size in recent human populations.

The possibility of smaller osteons in the cortical bone of Late Pleistocene human populations begs the question of how these histological features vary within individual skeletons among and between populations. The distributional characteristics of total osteon area (On.Ar) and Haversian canal area (H.Ar) are explored using data from three samples of historically known individuals: ribs and femora from eighteenth-century Huguenots in England (Spitalfields, n = 20), ribs and femora from nineteenth-century British settlers in Canada (St. Thomas, n = 21), and ribs from twentieth-century South African cadavers (University of Cape Town; following curatorial classifications, n = 10 white, 10 black, 10 colored). Neither histological variable is normally distributed. About 96% of the random variation is within the individual bone sample. There are no significant differences between sexes for either variable in any sample, and age has no effect in most instances. Femoral osteons are significantly larger than rib osteons within individuals and across samples. Haversian canal area is more variable than On.Ar, especially in the twentieth-century sample, where within-sample coefficients of variation are frequently >100%. Using modern centiles developed here, some Late Pleistocene long bone samples have On.Ar values below the range of modern variation. Because of ribs' smaller cross-sectional areas and less broadly ranging values for On.Ar, ribs would provide a preferable site for future comparative studies.

Adolescent↗
PubMed1998

Methods for improving the efficiency of estimating total osteon density in the human anterior mid-diaphyseal femur.

In order to preserve whole bone integrity and minimize destruction, paleohistologists often rely on histomorphometric data obtained from small areas (1.5-50 mm2) sampled within the anterior mid-diaphyseal femur. Because bone exhibits significant histological variation, the validity of results based on such sampling is questionable. The accuracy of various subareas (columns, rows, squares approximating dimensions and locations assessed by paleohistologists) in predicting total osteon density in the anterior mid-diaphyseal femur is assessed in the present study. Thirty-five specimens (12.7 mm wide, 100 microm thick, average area 56.7 mm2) were chosen at random from a skeletal population of 94 Inuits and Pueblo agriculturists. The specimens were photographed and enlarged; an acetate grid (12 columns, 10 rows, 120 squares, square = 1 mm2 of bone surface) was superimposed over the photograph; and secondary osteons and fragments were identified. Alternate columns (50% total area, T.Ar) predicted over 98% of entire section total osteon density. Two column combinations (15% T.Ar), separated by at least one column, predicted 91 to 95% of total osteon density. Individual column (8% T.Ar) predictability ranged from 48 to 86%. Two row combination (32 to 40% T.Ar) predictability values ranged from 86 to 95%. Individual rows (<1 to 20% T.Ar) predicted from 45 to 92% of total variation. Combinations of squares approximating areas and locations assessed by other paleohistologists ranged in predictability values from 80 to 94%. The results demonstrate that subareas of as little as 15% predict 95% of variation in total osteon density in the entire anterior mid-diaphyseal femoral section. A minimization of histological area evaluated without the loss of accuracy allows for a minimization of time invested in data collection and the utilization of partially damaged specimens.

Adolescent↗
PubMed1999

Histomorphological study on pattern of fluid movement in cortical bone in goats.

Streaming potential is considered one of the most important mechanisms to moderate the function of osteoblasts and osteocytes in bone growth, remodeling and fracture repair. The present study was designed to demonstrate the fluid flow pattern in the cortical bone matrix in an animal model using undecalcified histological techniques. Immediately after injection of ferritin into the tibia nutrient artery of four adult goats, the animals were euthanized. Undecalcified transverse and longitudinal blocks of cortical bone obtained from the tibial diaphysis were immersed in Perl's reagent and embedded in methyl methacrylate. Sections were cut and ground to 30-50 microm thickness for histomorphological evaluation at different magnifications and focusing levels. A serial grinding technique was used to validate the observations made at different focusing levels. As expected, ferritin was observed in the interstitial compartment in both transverse and longitudinal sections. In osteons sectioned transversely, the pattern of centrifugal movement of ferritin marker was demonstrated as single or multiple halos around the Haversian canal. The most apparent halo in osteons with multiple halos was the one found closest to the Haversian canal. The total number of identifiable single or multiple halos increased or was altered when counting was made with higher magnification or at different focusing levels, respectively. Irregular and incomplete ferritin halos indicated structural complexity of the osteons. Overall, the pattern of ferritin movement was consistent with bulk interstitial fluid flow influenced by both hydrostatic pressure and transudation. This study demonstrated for the first time multiple concentric halos of the fluid flow marker ferritin around Haversian canals in the cortical interstitial compartment. The results suggest that the undecalcified technique might be a useful method for qualitative and quantitative studies on cortical fluid flow.

Animals↗
PubMed1977

Three-dimensional studies on resorption spaces and developing osteons.

Resorption spaces and their continuations as developing osteons were traced in serial cross sections from decalcified long bones of dogs, baboons and a man, and from a human rib. Processes of formation of osteons and transverse (Volkmann's) canals can be inferred from three-dimensional studies. Deposits of new osseous tissue begin to line the walls of the spaces soon after termination of resorption. The first deposits are osteoid, usually stained very darkly by the silver nitrate procedure utilized, but a lighter osteoid zone adjacent to the canals occurs frequently. Osteoid linings continue to be produced as lamellar bone forms around them; the large canals of immature osteons usually narrow very gradually. Frequently they terminate both proximally and distally as resorption spaces, indicating that osteons often advance in opposite directions as they develop. Osteoclasts of resorption spaces tunnel preferentially into highly mineralized bone, and usually do not use previously existing canals as templates for their advance. Osteons evidently originate by localized resorption of one side of the wall of an existing vascular channel in bone, with subsequent orientation of the resorption front along the axis of the shaft. Advancing resorption spaces also apparently stimulate the formation of numerous additional transverse canal connections to neighboring longitudinal canals. Serial tracing and silver nitrate differential staining combine to reveal many of the processes of bone remodeling at work, and facilitate quantitative treatment of the data. Further uses in studies of bone tissue and associated cells are recommended.

Animals↗
PubMed2003

Osteon remodeling dynamics in the Cayo Santiago Macaca mulatta: The effect of matriline.

At the microstructural level, bones remodel throughout life. This process is recorded in bone cortex as osteons. A more comprehensive understanding of the interaction between genetic regulation and environmental factors in osteon remodeling will increase the value of this skeletal record and enable more accurate reconstruction of individual life histories. The purpose of this study was to examine the contribution of maternal lineage to normal age and sex variation in osteon remodeling dynamics in Macaca mulatta. Femoral cross sections from 57 Cayo Santiago-derived rhesus macaques representing five matrilines were examined to evaluate the effect of genetic relatedness on osteon remodeling dynamics. Analysis of variance revealed an effect of maternal lineage on osteon area and Haversian canal area. The other variables did not differ significantly among matrilines. Analysis of covariance revealed no significant interactions among age, sex, and matriline for any of the microstructural variables.

Age Factors↗