摘要:

AbstractThere is little information about the effects of short‐term non‐, hypo‐, and hyperfunction of teeth on the (1) mineralization patterns of intrinsic and extrinsic (Sharpey's) fibers and (2) mean number and diameter of Sharpey's fibers of adjacent alveolar bone. The mineral density of intrinsic and Sharpey's fibers and the size and number of Sharpey's fibers could indicate the relative strength of the attachment of a tooth to bone in various functional situations. In the present study, non‐ and hypofunctional situations were created by selective extraction of right molar teeth of the rat; the contralateral teeth were placed in hyperfunction by the surgery. In non‐ and hypofunctionals, intrinsic and Sharpey's fibers of the crestal third of the alveolus were less densely mineralized than in hyperfunctionals or untreated controls. Mean Sharpey's fiber diameters were significantly greater and their mean number/unit area significantly less in non‐ than in hypo‐ or hyperfunctionals or untreated controls (P<0.001). Mean Sharpey's fiber diameters in hyperfunctionals were significantly less than in untreated controls (P<0.05). Hypofunction ameliorated the effects of nonfunction on mean diameter and number of Sharpey's fibers, but had little effect on the density of mineralization of either the intrinsic or Sharpey's fibers of the alveolus, suggesting that their mineralization may be controlled by factors other than occlusal forces from the adjacent teeth. Thus changes in the stress/strain environment within the periodontium, coincident to altered occlusal function of the adjacent teeth, rapidly affects the morphology of intrinsic and Sharpey's fibers of alveolar bone and ensures that adequate tooth support is maintained in the new functio

ISSN:0003-276X    

DOI:10.1002/ar.1092270402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractTroubled by variations in the descriptions of shape, appearance, and content of matrix vesicles and the conflicting reports of increased numbers of vesicles in the mineralizing regions of the growth plate contrasted with larger numbers in the resting zone, we embarked on a review of matrix vesicles in the growth plate using a comparison of different fixation techniques. We found matrix vesicles resembling cell debris at all levels of the growth plate, with no particular association with mineral. Lipid bodies surrounded by a membrane of proteoglycan have also been seen in large numbers. The cell debris–like matrix vesicles have been the common finding in reports of digested centrifuged cartilage and may represent cytoplasmic processes. Lipid bodies surrounded by proteoglycan may be similar to the membrane‐bound vesicle described by Ali (Fed. Proc.,35:135–142, 1987) and by Bonucci (Clin. Orthod.,78:108–133

ISSN:0003-276X    

DOI:10.1002/ar.1092270403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractA microcomputer system was used to reconstruct, in the L5 dorsal root ganglion (DRG) of the rat, the three‐dimensional arrangement of primary neurons which had been labelled by application of horseradish peroxidase (HRP) and fluoro‐gold (FG) to various muscle nerves of the leg. Analysis of the data and animation of the reconstructed images with commercially available software were instrumental in identifying the preferential intraganglionic locations of the neurons innervating muscles such as the soleus (SOL), the gastrocnemius lateralis (GL), and medialis (GM), or parts of the GM. These locations appeared to be somewhat related to the position of the muscles in the posterior compartment of the leg. Additionally, the study provided quantitative estimates of muscle afferent neuronal populations, allowed a comparison of the labelling performances of HRP and FG, and finally indicated that few DRG neurons project to two different musc

ISSN:0003-276X    

DOI:10.1002/ar.1092270404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractNine‐month‐old female rats were subjected to right hindlimb immobilization or served as controls for 0, 2, 10, 18, and 26 weeks and were double‐labeled with bone markers. The right limb was immobilized against the abdomen and considered unloaded, while the left limb was overloaded during ambulation. Single‐photon absorptiometry was performed on intact femur; static and dynamic histomorphometry were performed on 20 μm thick undecalcified frontal sections of the proximal tibial metaphysis. Changes in the continuously overloaded limb was compared to that in both limbs of age‐matched control animals.Single‐photon absorptiometry detected increases of bone mineral density of +6%, +6%, and +5% in the proximal and +9%, +7%, and +10% in the distal femoral metaphyses after 10, 18, and 26 weeks of continuous overloading. Morphometrically, significant changes occurred in proximal tibial metaphyses compared to age‐matched controls; trabecular area increased +41% and +45%, trabecular number increased +31% and +32%, and trabecular separation decreased −30% and −31% after 18 and 26 weeks of overloading. A significant increase in mineral apposition rate (+38%) was found only at 26 weeks of overloading. Insignificant decreases in both eroded and labeled bone surfaces occurred at all time periods. The histomorphometric changes indicated that increased cancellous bone mass was caused by an increase in bone formation activity (i.e., increases in mineral apposition and bone formation rates) and a decrease in remodeling space (i.e., decrease in bone eroded surface). These findings indicate that the adult skeleton can quickly adapt to the increased biomechanical needs by increasing its cancellous bone mass with an adequate structural pattern. It further support Frost's postulate that increasing skeletal mechanical usage stimulates bone modeling and depresses bone remodeling to increase and

ISSN:0003-276X    

DOI:10.1002/ar.1092270405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractDiabetes induces osteopenia, which is characterized by a deficiency of osteoid and decreased activity of osteoblasts. We recently found that tetracyclines prevent the loss of osteoid and bone matrix and the degeneration of osteoblasts in diabetic rats by a mechanism independent of their antimicrobial efficacy. However, bone remodeling requires the activity of osteoclasts as well as osteoblasts. To determine the in vivo effects of tetracycline on osteoclasts in long bones, either a tetracycline (minocycline, TC) or its chemically modified non‐antibiotic analogue (CMT), 4‐de‐dimethylaminotetracycline, was administrated daily to streptozotocin‐induced diabetic rats by oral intubation. After 21 days, the rats were perfusion‐fixed with a mixture of formaldehyde and glutaraldehyde, and the humeri were dissected and processed for ultracytochemical demonstration of acid trimetaphosphatase (ACPase) activity. In untreated non‐diabetic (control) rats, the osteoclasts at the zone of provisional ossification exhibited abundant mitochondria and cisterns of rough endoplasmic reticulum (RER) throughout the cytoplasm, prominent stacks of Golgi membranes, and lysosomes in the perinuclear cytoplasm, and numerous various pale vacuoles in the cytoplasmic area adjacent to well‐developed ruffled border. Intense ACPase activity was observed in the Golgi saccules, lysosomes, pale vacuoles, and the extracellular canals of ruffled border. The reaction products were also noted along the resorbing bone surfaces associated with the osteoclast ruffled border. The osteoclasts in the untreated diabetic rats showed a cytoplasmic organization similar to that of the non‐diabetic control rats, but showed little or no ruffled border which was replaced by a broad clear zone in some of these cells. However, most of the osteoclasts on bone matrix in the diabetics were devoid of both a ruffled border and a clear zone. ACPase activity was detected in the osteoclast cytoplasm of diabetic rat, as in the controls, but to a much lesser extent along the broad clear zone facing the resorbing bone surfaces. The osteoclasts in TC‐treated diabetic rats possessed both a clear zone and a small ruffled border. However, in some cases, they lacked both structures reminiscent of the untreated diabetic cells. The osteoclasts of CMT‐treated diabetic rats exhibited structural and enzymatic features essentially identical to those of the non‐diabetic control rats. These results suggest that the diabetes‐induced osteopenia results, at least in part, from degeneration of osteoclasts (as well as atrophic osteoblasts) and that tetracyclines may be effective in preventing these abnormalities by a mechanism not dependent on the drugs' a

ISSN:0003-276X    

DOI:10.1002/ar.1092270406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAlthough the role of satellite cells has been confirmed during skeletal muscle growth and regeneration, their involvement during work‐induced muscle growth remains uncertain. In this study, chronically overloaded rat soleus muscles were ultrastructurally monitored following surgical ablation of synergists to examine cytological adaptations of satellite cells and myofibers. The left soleus muscle of 20 female Spague‐Dawley rats (7 weeks of age) was induced to hypertrophy by excising the contralateral plantaris and gastrocnemius muscles under pentobarbital anesthesia. Right limbs were sham‐operated and served as controls. On days 3, 7, 14, 21, and 30 after surgery, the soleus muscles were removed and processed for electron microscopy. Two morphologically distinct phases were noted in the surgically overloaded muscles. The first stage (week 1) was characterized by a significant increase in the number of satellite cells, and by more than half of the experimental muscle fibers displaying myofibrillar disruptions, mitochondrial alterations and glycogen pooling. The second phase (weeks 2–4) featured mostly normal, although larger appearing muscle fibers, with the satellite cell frequency remaining slightly elevated. These findings suggest that muscle fiber structural abnormalities, rather than an increase in muscle activity, may play a more significant role in the early activation of satellite cells during compensatory hypertrophy, whereas activation of satellite cells during the later stages may be in response to increased levels of muscle a

ISSN:0003-276X    

DOI:10.1002/ar.1092270407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractAffinity purified antibodies prepared against proteins isolated from fibrous sheath (FS) and outer dense fibers (ODF) were utilized in an immunocytochemical study of spermatids at various steps of spermiogenesis. This study, using the immunogold technique, was performed on sections of Epon or Lowicryl embedded tissues examined with the electron microscope. In the case of FS antibodies there was a selective immunoreactivity of the FS itself from step 10 onwards, but no reactivity over the plasma membrane associated FS anlagen. In addition there was a diffuse immunoreaction over the cytoplasmic matrix from step 9 until step 18 of spermiogenesis but no reactivity over the various types of dense bodies (e.g., granulated bodies, reticulated body, etc.) seen in the cytoplasm of these spermatids. In the case of ODF antibodies the ODF were immunolabeled throughout their development from step 11 onward. In addition to a diffuse immunoreactivity of the cytoplasmic matrix of spermatids from step 9 until step 18 of spermiogenesis, there was an immunolabeling of “granulated bodies.” These bodies appeared in relation to ER cisternae during steps 10–14, increased in number and size during steps 15–17 and decreased in number thereafter leaving only a few coarsely granulated bodies in the residual cytoplasm which detached from late step 19 spermatids. No other cytoplasmic structures were labeled with the ODF antibody‐gold complexes. Thus the granulated bodies appeared to serve as a transitory storage site for some proteins destined to form ODF, a major cytoskeletal element of the tail of rat sp

ISSN:0003-276X    

DOI:10.1002/ar.1092270408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractThe localization of progastricsin was studied in cells of abomasal mucosa from cattle of different ages and feeding regimes and compared to the localization of prochymosin and pepsinogen in the same material by use of an immunofluorescence technique with specific rabbit antibodies.Immunoreactivity for progastricsin was first found in calves at the age of about 45 days in surface mucous cells in the pit of the fundic gland. In older calves and adults, mucous neck cells also produced progastricsin. In the pyloric mucosa, on the other hand, traces of progastricsin immunoreactivity were found in the lower base of the pyloric gland even in newborn calves. When the calves grew older, progastricsin‐immunoreactive cells also developed in the pit and later in the neck of the pyloric gland; and the number of these cells in this region increased with age. The development of progastricsin‐producing cells seemed to be influenced only by age and not by the feeding of milk to the calves.The ontogeny of progastricsin, prochymosin, and pepsinogen exhibited an interesting pattern in cattle, as they started to be produced at three different ages and gave three different patterns of development in the cells of abomasal mucosa. The number of cells producing prochymosin was closely correlated with milk‐feeding, while the development of progastricsin was most related to the age of the calf. The most stable factor during the development of the cells in the abomasum was the number of cells producing pepsi

ISSN:0003-276X    

DOI:10.1002/ar.1092270409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractHeavily carbon‐laden (HC) macrophages, largely derived from the red pulp of the donor spleen, were injected into the splenic artery of recipient rats. Immediately after injection, HC macrophages were found only in the marginal sinus and in the splenic cords. With time after injection, they appeared successively at the periphery of the white pulp, in the deeper white pulp, and finally in and near the germinal centers, suggesting migration of HC macrophages from the marginal sinus towards the germinal centers. The number of HC macrophages in and near the germinal centers reached a peak at 12 h. Most of the HC macrophages in the white pulp were spherical or ovoid in shape with a diameter of 7–11 μm in sections, having an eccentric round or oval nucleus often with a distinct nucleolus and a cap‐like or horseshoe‐like cytoplasm filled with carbon. When immunostained with monoclonal antibodies against rat macrophage subpopulations, more than 90% of HC macrophages in the white pulp were found to be ED1+2−3−. A population of the same type of macrophages, both in morphology and phenotype, were found in the red pulp of the donor spleen. They were different from the major residents, red pulp scavenger macrophages, which were ED1+2−3−and larger in size and irregular in shape. These results suggest the presence of a distinct subpopulation of macrophages which actively migrate into the splenic white pulp including the germinal centers. A discharge of transferred macrophages from the red pulp to the general circulation i

ISSN:0003-276X    

DOI:10.1002/ar.1092270410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY

摘要:

AbstractRecent findings imply that germinal center paucity in old mice, at least in part, results from a defect in the mechanisms responsible for the transport of antigens to lymphoid nodules (follicles) and the consequent impairment of the antigen retaining reticulum (ARR) of follicular dendritic cells (FDCs). The present objective was to observe the kinetics of lymph node germinal center development in old mice having antigen transport and ARR deficits. Germinal center development was monitored in popliteal (PLN) and axillary (AXLN) lymph nodes of 6–;8 wk and 23‐mo‐old horseradish peroxidase (HRP) immune C57BL/6 mice. Using the selective binding of germinal center B cells for peanut agglutinin (PNA), germinal centers were identified in serial vibratome sections following histochemical labeling with PNA‐peroxidase conjugates at times 0, 15 min, 1, 3, 5, and 10 days after footpad challenge with 8 μg HRP. To follow the fate of preexisting (environmental antigen‐induced) germinal centers and the development of de novo (HRP‐induced) germinal centers, it was essential to distinguish between these germinal centers. Accordingly, PNA positive germinal centers associated with HRP‐retaining (peroxidase positive) ARR were identified as de novo germinal centers and germinal centers not associated with a peroxidase positive ARR were classified as preexisting germinal centers. Kinetic analysis of PNA positive germinal centers showed the following: (1) Preexisting, environmentally‐induced germinal centers dissociated and disappeared by day 3 as indicated by a decline in their numbers after antigen injection; the process of germinal center dissociation remained unaffected by aging. (2) The latency of de novo germinal center appearance was approximately equal in duration (∼3 days) to the disappearance of preexisting germinal centers. (3) The number and size of de novo HRP‐induced germinal centers increased through the experimental period in young lymph nodes, but in old mice these parameters were depressed, resulting in a significant germinal center deficit. (4) The ratio of HRP‐retaining ARR to de novo induced germinal centers was 1:1 in young and responder old mice. This ratio was not affected by aging. This finding favored the concept that antigen retention in ARR is a requirement of germinal center development. The observations supported our hypothesis that germinal center development, at least in part, depends on a normal antigen transport by showing that in aged mice with defective antigen transport‐related ARR and iccosome deficits there is an impaired develop

ISSN:0003-276X    

DOI:10.1002/ar.1092270411

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1990

数据来源: WILEY