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At least 19 recordsLinked to original sources
PubMed1990

Morphological relationships between osteoclasts and bone resorption surfaces on mouse parietal bones.

Parietal bones from mice 1-20 weeks of age were histochemically stained for detection of acid-phosphatase activity and then observed by the light microscope to evaluate the distribution and shape of osteoclasts on the inner surface of their bones. After microscopic examination, the same bones were macerated by NaOCl to both remove organic materials and expose the mineralized surface. The inner surface was then examined by scanning electron microscopy and the observations were compared with the light micrographs of the areas where osteoclasts were located. The bone resorption areas were identified as well-demarcated rough areas, and corresponded to the areas where osteoclasts were distributed. In young mice, osteoclasts observed in the bone resorption areas, which were composed of accumulations of irregular concavities, were mainly polygonal or round in shape. In adult mice, elongated osteoclasts with longer or shorter cytoplasmic processes were predominant; the bone concavities were also elongated and gathered in a flame-like pattern. The findings suggest that osteoclasts change shape according to their resorptive activities and that the activities differ between growing bones and those where growth has ceased, probably in relation to the modeling and remodeling of the bone.

Acid Phosphatase↗
PubMed2003

Angiogenesis after sintered bone implantation in rat parietal bone.

We studied the effect of bone substitutes on revascularization and the restart of blood supply after sintered bone implantation in comparison with synthetic hydroxyapatite implantation and fresh autogenous bone transplantation (control) in rat parietal bones. Methods for the study included the microvascular corrosion cast method and immunohistochemical techniques were also used. The revascularization of the control group was the same as that for usual wound healing in the observations of the microvascular corrosion casts. The sintered bone implantation group was quite similar to that of the control group. In the synthetic hydroxyapatite group, immature newly-formed blood vessels existed even on the 21st day after implantation and the physiological process of angiogenesis was interrupted. Immunohistochemically, vascular endothelial growth factor (VEGF), which activates angiogenesis, appeared at the early stages of both the control group and the sintered bone implantation group. VEGF reduced parallel with the appearance of the transforming growth factor factor-beta-1 (TGF-beta-1), which obstructs angiogenesis, and the angiogenesis passed gradually into the mature stage. In the hydroxyapatite implantation group, TGF-beta-1 appeared at the early stage of the implants. The appearance of VEGF lagged and it existed around the pores of hydroxyapatite even on the 21st day of the implantation. Proliferation and wandering of endothelial cells continued without any maturing of the vessels. These findings suggest that the structure and the components of the implant material affect angiogenesis after implantation as well as new bone formation.

Animals↗
PubMed1992

Stimulative effects of cadmium on bone resorption in neonatal parietal bone resorption.

Effects of cadmium on bone resorption were investigated using neonatal mouse parietal bone culture system. Cadmium at 0.5 microM and above stimulated hydroxyproline release as well as 45Ca release. As cadmium-stimulated bone resorption was inhibited by calcitonin, bone resorption induced by cadmium is osteoclast-mediated bone resorption. CI-1, collagenase inhibitor, depressed cadmium-stimulated bone resorption in a dose-dependent manner. Osteoblasts are also involved in cadmium-induced bone resorption. Indomethacin-inhibited cadmium-stimulated bone resorption and cadmium-treated bones released prostaglandin E2 to a greater extent than untreated bones. Cadmium-stimulated bone resorption was shown to be dependent on the production of prostaglandin E2. 3-Isobutyl-1-methylxanthine potentiated cadmium-stimulated bone resorption and verapamil depressed it. It is possible that an increase in levels of cAMP and calcium ion in bone cells is involved in cadmium-induced bone resorption. From these results, cadmium was found to stimulate osteoclast-mediated bone resorption which is dependent on prostaglandin E2. Second messengers in cadmium-induced bone resorption may be cAMP and calcium ion.

Animals↗
PubMed1996

Morphological changes of autoclaved autogenic bone implantation and autoclaved autogenic bone supplemented with allogenic demineralized bone matrix in rat parietal bone.

The healing process of resected, autoclaved (121 degrees C, 20 minutes) and re-implanted bone in the rat parietal bone was compared with that of autoclaved bone that was supplemented with allogenic bone matrix (AAA-bone), using a scanning electron microscope and a light microscope. In the implant without AAA-bone, bone union and replacement of the autoclaved bone was seen at 2 weeks after implantation. There was no evidence of any inflammatory reaction around the autoclaved bone. The implant was gradually replaced by the new bone. In the implant with AAA-bone, the new bone formation around the implanted bone was more abundant than that of the implant without AAA-bone. An inflammatory reaction was also observed after 1 week. The replacement of the implant with AAA-bone was inferior to the nonsupplemented group. The reason for the poor replacement was the disturbance of the blood supply in the implant by abundant new bone formation. In these results, the autoclaved bone re-implantation was an excellent bone substitute with osteoconductive ability and biocompatibility. The implantation with AAA-bone was good for the new bone formation, but the position and the technique of supplement with AAA-bone have to be more deeply investigated.

Animals↗
PubMed1994

[Study of bone formation in fetal rat parietal bone using serum-free bone-forming organ culture system: effect of insulin on bone formation].

Serum-free bone-forming organ culture system using twenty-day fetal rat parietal bones was established. The effects of insulin on bone formation were studied in this system. Bones were cultured on grids and placed on a rocking platform under an aerobic condition. This condition increased the bone-forming activities of cultured rat parietal bones. The calcium content, dry weight of bone, and lactate produced by bone tissue in the medium were measured to study the precise bone-forming process of vital bones. Using this improved bone-forming organ culture system, insulin increased calcium content and dry weight of bone. These effects were maximum in bones treated with insulin at 10(-6) M. Histo-morphometrical analysis showed that the areas of mineralized bone and bone matrix increased, and that many osteoblasts and few osteoclasts appeared in bones treated with insulin at 10(-6) M or higher. Insulin inhibited the release of 45Ca into the medium. From these results, it was suggested that insulin has a stimulatory effect on bone formation, enhancing both bone mineralization and bone matrix formation.

Animals↗
PubMed2000

Effect of irradiation on autogenous bone transplantation in rat parietal bone.

To determine the appropriate time for bone reconstruction after irradiation, the healing process after autogenous iliac bone transplantation in the irradiated parietal bone was examined by scanning electron microscopy and light microscopy. Bone transplantation was carried out at the second and the fourth weeks after Cobalt-sixty (60Co) irradiation with calculated dose and fractionation. Animals without irradiation were used as control. The results show the appearance of mesenchymal cells and blood vessels around the transplantation to be extremely few one week after transplantation which was carried out at the second week after irradiation. These inhibitions were still seen two weeks after transplantation. Four weeks after transplantation, there were no differences in the bone formation among the experimental groups. Bone formation in the transplantation at the fourth week after irradiation was similar to that of the control group. Microvascularization in the transplantation at the second week after irradiation was inhibited one week after transplantation. The delay in bone healing was responsible for the retardation of revascularization and caused microcirculatory failures as well as the damage of osteogenic cells. It is quite clear that damaged cells and tissues recovered by the elapse of time under the irradiation procedure employed in this study and also that bone formation was carried out in the physiological process. We think that bone transplantation after irradiation should be done after recovery from the radiation damage to the periosteal cells and the blood vessels.

Animals↗
PubMed2002

Effects of enamel matrix derivative on mineralized tissue formation during bone wound healing in rat parietal bone defects.

Enamel matrix derivative (EMD: Emdogain) has been reported to stimulate the biosynthesis and regeneration of trabecular bone. To address whether the biological action of EMD is dependent on the local environment of osseous tissue, circular perforations were made in parietal bones and immediately filled with either EMD or its carrier, propylene glycol alginate (PGA), as control. On post-operative days 4-60, the dissected bones were examined by various histological techniques. New bone matrix, which was immunoreactive for bone sialoprotein (BSP), was formed from the periosteum at the peripheral area of perforations. Different from the findings reported in injured long bones, mineralized tissue was produced in the regenerating connective tissue within bone defects. This mineralized tissue was hardly immunostained for BSP, contained few collagen fibres, and lacked osteocytic lacunae and layers of osteoblasts and osteoid. Energy-dispersive X-ray analysis showed that Ca and P weight % and Ca/P molar ratio of this mineralized tissue were similar to or slightly higher than those in the pre-existing parietal bones. In addition, most multinucleated cells located in mineralized tissue lacked a ruffled border structure and showed weak immunoreaction for the lysosomal cysteine proteinase, cathepsin K, whereas those located in the bone matrix exhibited ruffled borders and strong cathepsin K expression. However, multinucleated cells located in both tissues were strongly stained for tartrate-resistant acid phosphatase. The volume fraction of such mineralized tissue appeared to be higher in EMD-applied bones than in PGA-applied controls. The mineralized tissue-forming stromal cells within bone defects appeared to show greater accumulation in EMD-applied bones than in PGA-applied controls. Our results suggest that the bioactive effects of EMD on bone wound healing and mineralized tissue formation depend, at least in part, on the local osseous environment where EMD has been applied.

Animals↗
PubMed1994

Interleukin-6 does not mediate the stimulation by prostaglandin E2, parathyroid hormone, or 1,25 dihydroxyvitamin D3 of osteoclast differentiation and bone resorption in neonatal mouse parietal bones.

The cytokine interleukin-6 (IL-6) was produced by neonatal mouse parietal bones during a 6- or 48-hour culture period in response to prostaglandin E2 (PGE2) and bovine parathyroid hormone (PTH) 1-34 fragment but not 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. At the same time there was an increase in tartrate-resistant, acid phosphatase-positive osteoclasts (TRAP+OC) with all three osteotropic effectors over 6 hours, and an increase in 45Ca release over 48 hours. TRAP+OC numbers on PGE2-stimulated bones were positively correlated with IL-6 concentration. Our aim was to determine if IL-6 mediated this response. Recombinant human IL-6 (rhIL-6) was added to parietal bones in culture at concentrations within the range that PGE2 or PTH would produce during incubation. However, over 6 or 48 hours, rhIL-6 did not stimulate TRAP+OC to increase in number nor did it cause an increase in calcium release over 48 hours. Adding an antibody against mouse IL-6 to bone cultures stimulated with PTH or PGE2 neutralized the resulting IL-6 bioactivity by up to 92% but did not inhibit TRAP+OC formation. We conclude that although IL-6 is produced in response to two important stimulators of bone resorption, it does not mediate osteoclast differentiation or bone resorption in this model.

Acid Phosphatase↗
PubMed1997

Thickness map of parietal bone in Korean adults.

The parietal bone remains the most common donor site for a bone graft in treating facial bone fractures, especially those involving orbital walls. Despite this potential clinical usefulness, anthropometric data on the parietal bone is lacking. Only one Korean and a few foreign studies report on its thickness, measured at two and three points of each of two parietal bones in a given subject, respectively. These studies, however, fall short of offering enough information for locating the optimal harvest point of the parietal bone for bone grafting. This study was thus aimed at constructing a thickness map that provides the mean parietal bone thickness at various points and determines the difference between them. Eighty-eight parietal bones were obtained from 44 Korean adult skulls for this study. Parietal bone thickness was measured at 15 points, spaced at regular intervals on each parietal bone of a given skull, using a Techlock GM 21 caliper gauge. The mean bone thickness at each of the 15 points of the bone and at the corresponding points of the opposite parietal bone was obtained in all skulls studied. The mean thickness at each point of measurement on two opposite parietal bones was compared using the paired Student's t test. Mean thickness did not differ significantly. The thickness in the same bone varied widely depending on the points of measurement. The thickest part, the posteromedial region of the parietal bone near the lambda, was 6.67 +/- 1.41 mm (mean +/- standard deviation [SD]) thick, and it became thinner toward the diagonal (anterolateral) direction, to the thinnest part, 4.73 +/- 1.19 mm (mean +/- SD) thick, near the pterion. It is hoped that our thickness map can serve as a practical guide for choosing an ideal site on the parietal bone for a bone graft of desired thickness.

Adult↗
PubMed1994

Effects of insulin on in vitro bone formation in fetal rat parietal bone.

We examined the effects of insulin on bone formation including the mineralizing process. Twenty-day fetal rat parietal bones were cultured for 96 h on grids in a serum-free medium. For the precise assessment of bone formation, histomorphometry, with an image analyzing system, was used to measure the areas of mineralized bone and bone matrix, and the numbers of osteoblasts and osteoclasts. In order to confirm the effects of insulin on bone mineralization, the calcium content of the bone and the release of previously incorporated 45Ca into the medium were measured. Insulin, at a concentration of 10(-6) M or higher, increased the areas of mineralized bone and bone matrix, and the number of osteoblasts. Osteoclasts were seldom observed in bones on day 0 or in bones treated with insulin. In bones treated with insulin at a concentration of 10(-6) M, the calcium content of bone increased. At an insulin concentration of 10(-7) M or higher, the dry weight of decalcified bone increased. Lactate production in the medium increased dose-dependently. The inhibited release of 45Ca in bones indicated that insulin acts by increasing calcium retention. We demonstrated that insulin has an effect on bone-forming and bone-resorbing cells to enhance the bone forming process from matrix formation to mineralization.

Animals↗
PubMed2003

Hyperpneumatization of the temporal, occipital and parietal bones.

Hyperpneumatization of the temporal bone with extension into the occipital bone and even the parietal bones is a rare condition. According to a review of the literature, it mostly appears unilaterally in men and on the right side. Often it is discovered when complications like pneumatocele or pneumocephalus appear. The authors review and analyze all reported cases of hyperpneumatization, its symptoms, complications and treatment. We present a patient with extensive pneumatization found in the mastoid process, temporal bone, occipital bone and both parietal bones, who was discovered accidentally. The cause of the extension of pneumatization into the occipital and parietal bone is probably incomplete closure of the occipitomastoid synchondrosis and lambdoid and sagital sutures, which usually close in early adulthood and later, even in the 30s. Asymptomatic patients should be aware of possible complications, and in case of complications, operative therapy is often indicated.

Adult↗
PubMed2005

Two types of bone resorption lacunae in the mouse parietal bones as revealed by scanning electron microscopy and histochemistry.

To understand the bone resorption process on the basis of the morphology of bone resorption lacunae, the inner surface of parietal bones in juvenile mice was exposed with a treatment of ultrasonic waves or NaOCl treatment and examined by scanning electron microscopy (SEM). The bone resorption lacunae were divided into two types (I and II) according to differences in morphological features of their walls; the wall of type I lacunae was covered with loose collagen fibrils, while that of type II lacunae was smooth with almost no fibrillar structures. Collagen fibrils in type I lacunae treated with ultrasonic waves differed in appearance from those treated with NaOCl; the collagen fibrils were thin and displayed a smooth surface in type I lacunae treated with ultrasonic waves, while they were thick and showed a rough surface in those treated with NaOCl-probably because superficial uncalcified collagen fibrils were digested with the chemical. The results indicated that type I lacunae occupied 77% of all of the bone resorption lacunae treated with ultrasonic waves, but 51% of those treated with NaOCl. This finding led to the idea that type I lacunae can be subdivided into two: lacunae (Ia), covered with partially calcified fibrils as well as superficial uncalcified fibrils; and lacunae (Ib), covered only with uncalcified fibrils. The presence of uncalcified fibrils in the bone resorption lacunae was further confirmed by backscattered electron (BSE) imaging of SEM. Histochemistry for acid phosphatase or immuno-histochemistry for cathepsin B or carbonic anhydrase in combination with SEM revealed that type I lacunae were located under osteoclasts but type II lacunae were not. These findings indicate that type I lacunae are in the process of bone resorption by osteoclasts, while type II lacunae are in the final stage of bone resorption and free from osteoclasts. Bone resorption may thus proceed in the order of Ia, Ib, and II.

Animals↗
PubMed1984

Sex differences in bone resorption: a scanning electron microscopic study of mouse parietal bones.

Bone resorption surfaces formed by osteoclasts can be identified as rough areas by scanning electron microscopy (SEM). In this study, the endocranial surfaces of mouse parietal bones were examined by SEM at 1, 4, 6, 8, 14 and 20 weeks of age in an attempt to understand the bone resorbing activity after the cessation of bone growth. On the inner surface of the parietal bones, the rough areas, composed of a group of 8 to 30 microns wide concavities, can be divided into two distinct groups (type I and type II). The surface of type I areas appeared irregularly rough and those of type II revealed feather, fire-flame, or wave-like patterns due to characteristic arrangements of the concavities. The rough areas occupying the inner surface of the parietal bones made up about 60% of the surface area at 1 week and about 5% at 4 weeks in both sexes. The rough areas were all type I at this age. After puberty, the rough areas in males occupied about 10% of the inner surface until 20 weeks and consisted of large type I and small type II areas. In females, the proportion of the rough areas increased after puberty and occupied about 40% of the endocranial surface at 14 and 20 weeks. The type I areas were much larger, increasing in size with age and eventually occupying a large proportion of the rough areas. The sex differences in the rough areas were reversed by gonadectomy. The results suggest that male and female gonadal products, possibly sex hormones, have respective inhibitory and stimulatory effects on the formation of bone resorptive surfaces, and may be responsible for the sex differences in the size and morphological features of the areas on the bone surfaces.

Age Factors↗
PubMed1993

[Anatomic study of parietal bone for use as bone graft material].

Anatomic parietal bone structures of 45 adult Chinese cadavers (90 sides) were investigated by measuring the burr holes. The results were as follows. The average thickness of parietal was 5.059 mm and showed an increase with age. In the senile group it was 1.3-1.9 mm thicker than that of the pubertal and middle age. The measurement revealed significant difference in various areas and the posterior and middle parts of the bone was thicker than that of the anterior part. The thickness of diploic layer decreased with age and even disappeared. The above findings may provide a basic data for taking bone graft from parietal bone in clinic.

Adolescent↗
PubMed2003

Regional thickness of parietal bone in Korean adults.

To clarify the clinical utility of the parietal bone graft in maxillofacial reconstruction, we performed an anatomical study by measuring the regional thickness of the parietal bone in 47 Korean adult dry skulls. Before sectioning of the calvaria, the appropriate anatomical landmarks were marked on each specimen. We measured the total thickness of the parietal bone, and the thickness of the outer and inner cortical plates at various points in each section of parietal bones using a digital caliper under the stereomicroscope. The total thickness of the parietal bone ranged from 5.04mm to 7.17mm, and there was no statistical difference in the total thickness of the parietal bone on the same points bilaterally. The parietal bone tended to be thicker toward the lambda point than at the coronal suture area. On the other hand, the outer plate of parietal bone was thickest at the point nearest to the coronal suture, and the inner plate proved thickest at the posteromedial area. In conclusion, this study showed that the better donor site of the parietal bone for maxillofacial reconstruction is located at its more posterior and medial area.

Adult↗