bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transmission electron microscopic demonstration of vimentin in rat osteoblast and osteocyte cell bodies and processes using the immunogold technique
Authors: Shapiro Frederic , Cahill Christopher , Malatantis George , Nayak Ramesh C. 
Published: February 2005

AbstractBackground: The immunogold labeling technique and transmission electron microscopy were used to demonstrate the expression and position of the intermediate filament vimentin in rat osteoblast and osteocyte cell bodies and cell processes. Conventional light and transmission electron microscopic studies of bone cells demonstrated adjacent cell linkage to be mediated by osteoblast and osteocyte processes present within the canalicular system traversing the bone matrix. The cell processes were filled with densely packed filaments, many of which have been shown previously to be actin microfilaments. The appearance, however, of 10 nm diameter filaments in some cell processes and the fact that the intermediate filament vimentin has been defined in many cells of mesenchymal origin raised the possibility that some of these filaments might be vimentin. The ultrastructural colloidal gold immunochemical technique allowed for demonstration in situ of the expression of vimentin filaments plus accurate definition of their position.Methods: The studies were performed in newborn rat femoral and tibial diaphyseal cortical bone and in 1‐week‐old repair bone from 2.4 mm diameter defects made through the lateral cortex in 6‐week‐old rat femurs and tibias. The bone tissues for the immunochemical study were fixed in 1% glutaraldehyde, 4% paraformaldehyde, and 0.1 M phosphate buffer (pH 7.4) for 2 days. Decalcification was performed in 6% EDTA for 2–3 days. Infiltration involved use of Lowicryl resin K4M, and the embedding and curing processes were performed in a cryostat with temperatures −30°C. An antivimentin monoclonal antibody was used for labeling using the postembedding technique. Effective antibody dilutions ranged from 1:10 to 1:200, with the dilutions of 1:25 and 1:100 showing the best combination of filament labeling with the least matrix background. The grids were exposed to 10 nanometer gold colloid conjugated goat anti‐mouse IgM for demonstration of binding.Results: Vimentin immunolabeling was defined clearly in relation to filaments within the osteoblast and osteocyte cell body cytoplasm, throughout the entire length of the osteoblast and osteocyte cell processes, and in close relationship to the intercellular gap junctions which were present within the cell processes both close to the cell bodies and within the canaliculi well away from them.Conclusions: Immunogold labeling demonstrates the presence of the intermediate filament vimentin in osteoblast and osteocyte cell bodies and processes of rat bone. Vimentin distribution is not concentrated to specific areas, is present throughout the extent of the bodies and processes, and is seen immediately adjacent to gap junctions. © 1995 Wiley‐Liss, Inc.
Altered mitochondrial morphology of rat embryos in diabetic pregnancy
Authors: Yang Xiaolin , Håkan Borg L. A. , Eriksson UlF J. 
Published: February 2005

AbstractBackground: Previous studies in vivo and in vitro have suggeted that the oxidative metabolism of the embryo may have a role in the treatogenicity of diabetic pregnancy. In particular, the production of reactive oxygen species by the embroyonic mitochondiria has been implicated in the teratological process. The induction of congenital malformations by the diabetic milieu occurs during the early embryonic development. The present study aimed to estimate the role of the embryonic mitochondria in the teratological process of diabetic pregnancy by studying mitochondrial morphology in the embryos exposed to a diabetic environment in vivo or in vitro during early organogenesis and late fetal development.Methods: For studies in vivo embryos of control or streptozotocin‐dia‐betic rats were taken at gestational days 9–11 and sujected to light and electron microscopical analysis. The brain, heart, and liver of day‐15 fetuses were also observed. For studies in vitro day‐9 embryos of normal rats were cultured in a whole‐embryo culture system for 48 hours. The culture media were supplied with high conectration of diabetes‐related substrates and metabolites, and their effect on structure of embryonic neuropeithelial cells determined.Results: The light microscopoical observations demonstrated numberous cytoplasmic vaculoes in the ectoderm of day‐9 embryos and the neuroepithelium and blood cells of day‐10 and day‐11 embryos of diabetic rats. Ultrastructuraily, these vacuoles were found to be mitochondria undergoing large‐amplitude swelling with loss of matrix density and disturbed cristae. In contrast, no Mitochondrial differences were found in the brain, heart, and liver, when day‐15 fetuses from normal and diabeic rats were compared. Ultrastructural analysis of day‐9 embryos cultured for 48 hours in the presnce of high conectrations of D‐Glucose, pyruvate, β‐hydroxybutyrate, and α‐ketoisocaproate also showed high‐amplitude mitochondrial swelling in the neuroepithelium. The motochondrial swelling was, however, not found in embryos cultured in a high conectration of L‐glucose, excluding simple osmotic effects of the diabetes‐related substrated and metabolites.Conclusions: The mitochondrial morphological changes appeared in embryos subjected to a diabetic environment during a time period when the congenital malformations in diabetic pregnancy are induced. The results support the notion that embryonic mitochondria are involved in the teratological process of diabetic pregnancy. © 1995 Wiley‐Liss, inc.
Estimation of capillary length density in skeletal muscle by unbiased sterological methods: II. Use of vertical slices of unknown thickness
Authors: Artacho‐Pérula Emilio , Roldán‐Villalobos Rafael 
Published: February 2005

AbstractBackground: The capillary network of the skeletal muscle was analyzed from a quantitative point of view with the purpose of determining the capillary length density—Lv(cap/mus). A recent stereological method was applied to estimate this quantity using vertical slice of unknown thickness.Methods: First, the whole muscle was systematically sampled according to the fractionator method. The capillary length density was estimated on each chosen field of vision where the vertical axis was always identified as parallel to the major axis of the muscle fibers. Three measurements were performed: count of intersections between capillaries and cycloid test lines, count of intersections between capillaries and straight test lines, and count of capillary end points corresponding to the intersections of capillaries with the parallel planes of the vertical slices.Results: The estimated capillary length density was 1,578 mm per mm3 of skeletal muscle tissue. The average thickness of the vertical slices was also estimated as 23.4 μm, which is roughly 6% less than the thickness measured using the microcator information on the microscope stage displacement.Conclusions: The advantages of this methodology were bases on two main features: the method is assumption‐free on the degree of capillary and muscle anisotropy, and the thickness of the vertical slices need not be known nor constant. © 1995 Wiley‐Liss, Inc.
Skeletal alterations in hypophysectomized rats: I. A histomorphometric study on tibial cancellous bone
Authors: Yeh James K. , Chen Meng‐Meng , Aloia John F. 
Published: February 2005

AbstractBackground: Hypophysectomy (HX) results in a cessation of bone growth and a decrease in bone metabolism. The purpose of this study is to examine the effect of HX on the static and dynamic histomorphometry of cancellous bone in the secondary spongiosa of the proximal tibial metaphysis in rats.Methods: Female rats, at 2 or 3 months of age, were HX and sacrificed at 0, 5 days, 2 and 5 weeks after the surgery. Age‐matched intact rats served as controls. Cancellous bone histomorphometry was performed on doublefluorescent labeled, 30‐um‐thick sections of the proximal tibia. Tartrateresistant acid phosphatase histomorphometry was performed at 5 days on HX and control rats to evaluate the resorption in the metaphyseal bone.Results: Although the intact rats gained in body weight, tibial length, tibial weight, and density after 5 weeks, these changes did not occur following HX. As compared to the basal group, HX resulted in a decrease in the density and dry weight of the metaphysis. The histomorphometric data showed that the cancellous bone volume and trabecular number of the secondary spongiosa were decreased and the separation was increased in the HX rats. The dynamic results showed that HX significantly decreased longitudinal growth rate and tissue‐based bone formation and resorption. However, the bone surface‐based eroded surface, labeled surface, the mineral apposition rate, and the bone formation rate did not differ between the intact and the HX rats at either the 2 or 5 weeks study. Five days after HX, the bone surface and tissue‐based osteoclast surfaces were significantly lower in the HX than in the intact rats.Conclusions: Pituitary hormone deficiency results in cancellous bone loss. The bone loss is due primarily to the suppression of longitudinal growth‐dependent bone gain and the inhibition of tissue‐based bone turnover with a lower bone formation relative to bone resorption. The surfacebased bone turnover is not affected. © 1995 Wiley‐Liss, Inc.
Skeletal alterations in hypophysectomized rats: II. A histomorphometric study on tibial cortical bone
Authors: Chen Meng‐Meng , Yeh James K. , Aloia John F. 
Published: February 2005

AbstractBackground: Pituitary hormones play an important role in bone growth, modeling, and remodeling. The purpose of this study is to examine the effect of hypophysectomy (HX) on tibial cortical bone with histomorphometry.Methods: Forty‐Five female Sprague‐Dawiey rats, at 3 months of age, were hypophysectomized or served as intact controls. They were sacrificed at 0, 2, and 5 weeks after the surgery. Cortical bone histomorphometry was performed on double‐fluorescent‐labeled 30‐mcm‐thick sections of the tibial shaft.Results: The dry weight and density of tibial diaphysis and the cortical bone area of the tibial shaft in the HX rats were significantly lower (P<0.05) than that of the age‐matched intact rats, but did not differ between the HX and basal control rats. The dynamic data show that the bone formation parameters (labeled surface, mineral apposition rate, and bone formation rate) were profoundly decreased (P<0.01) on both the periosteal and endocortical surfaces in the HX rats as compared with the age‐matched intact rats at the 2 and 5 weeks. However, the decrease in the labeled surface was much less on the endocortical envelope than on the periosteal envelope in the HX rats. Although no significant change was detected in the medullar size between the HX and age‐matched intact rats, the eroded surface on the endocortical surface was greater (P<0.05) in the HX rats than in the intact rats at either time point.Conclusions: Hypophysectomy‐suppressed, radial growth‐dependent bone gain without a bone loss in the tibial shaft of the young rat. This is associated with decreased modeling‐dependent bone formation. A greater eroded surface on the endosteum did not affect the marrow size at 5 weeks after hypophysectomy. © 1995 Wiley‐Liss, Inc.
Neonatal hypothyroidism causes delayed sertoli cell maturation in rats treated with propylthiouracil: Evidence that the sertoli cell controls testis growth
Authors: de Franca Luiz Renato , Hess Rex A. , Cooke Paul S. , Russell Lonnie D. 
Published: February 2005

AbstractBackground: The testes of rats treated neonatally with propylthiouracil (PTU) grow to almost twice their normal size. The cause of testicular enlargement has been suggested to be the result of delayed maturation of Sertoli cells, allowing Sertoli cell division to occur beyond the 15th postnatal day, the commonly recognized cutoff date for Sertoli cell divisions. It has been shown that an increased population of Sertoli cells in postnatal development supports increased numbers of germ cells in adult animals. After examining developing rats treated neonatally with PTU, we hypothesized that an approximate 10‐day delay in maturation was occurring and proceeded to test this hypothesis experimentally. Thus the purpose of this report was to determine if a 10‐day delay in maturation could explain the increased numbers of Sertoli cells and increased testis size in PTU‐treated animals.Methods: Both control animals and animals treated neonatally with PTU N = 5/group were sacrificed at 15 and 25 days of age and prepared for electron microscopy.Results: Micrographs show and morphometric ultrastructural analysis of numerous parameters demonstrated at the 95% probability level that Sertoli cells from 25‐day‐old PTU animals are not different in size and most constituents (volume and surface area) from 15‐day‐old control animals and are less mature than 25‐day‐old control animals. Mitosis of Sertoli cells was observed in PTU‐treated animals in 25‐day‐old animals but not in agematched controls. The number of Sertoli cells in 25‐day‐old PTU‐treated animals is significantly increased over age‐matched controls. Micrographs show the presence of immature Sertoli cell nuclei in 25‐day‐old animals receiving PTU as well as increased germ cell degeneration in this group. Sertoli cell tight junction formation is also delayed in PTU‐treated animals as compared with controls.Conclusions: Together, the data show that delayed maturation of Sertoli cells occurs in treated animals that corresponds to a minimum of 10 developmental days. In the immature state, Sertoli cells continue to divide. Data presented herein and published data related to PTU treatment indicate that delayed maturation of the Sertoli cell results in delayed maturation and proliferation of other testicular cell types. From this and from published data, the hypothesis is presented that the Sertoli cell is responsible for the overall control of testis development. © 1995 Wiley‐Liss, Inc.
Functional implication of autophagy in steroid‐secreting cells of the rat
Authors: Yi Jing , Tang Xue Ming 
Published: February 2005

AbstractBackground: Autophagy, while frequently observed in embryonic cells undergoing differentiation and in pathologically altered cells, appears to occur less commonly in normal, fully differentiated cells. Our previous work revealed that the frequency of autophagic activity was rather high in the Leydig cells of rat testes, but the functional significance of autophagy in Leydig cells remains obscure. The purpose of the present study is to investigate the possible role of autophagy in steroid‐secreting cells.Methods: The autophagic activity was investigated in two steroid‐secreting cells, e.g., Leydig cells and adrenocortical fasciculata cells of rats. Cytidine monophosphatase (CMPase) cytochemistry was utilized to show the activity of lysosomal enzymes in autophagosomes. Electron microscopic morphometry was employed to analyze the frequencies of autophgy in the cells of the rats intact or treated with related hormones resulting in a hyper‐ or hypo‐secretion of testosterone and corticosterone.Results: Autophagy took place in normal steroid‐secreting cells with higher frequencies than in many other cells including the tubular cells of kidney and hepatocytes. The large number of autophagosomes or autophagic vacuoles allowed to outline the autophagic process in these cells. The C‐shaped double‐membrane profiles tending to demacate a portion of cytoplasm were referred to as pre‐autophagosomes. So called early autophagosomes were the vacuoles enclosed completely by double delimiting membranes, containing normal‐looking cellular components. The majority of sequestered organelles appeared to be mitochondria and smooth endoplasmic reticulum. The autophagosomes starting digestion were considered as late autophagosomes or autophagic vacuoles, the indications of which were the destruction of their contents or the presence of lysosomal enzymes demonstrated by a positive CMPase reaction. Residual bodies were frequently observed to be exocytosed. The quantitative assay revealed an alteration of autophagic activity in close relation with steroid‐secreting states. The number of autophagosomes was one‐fold higher in hyposecreting Leydig cells after 2 days testosterone administration, and three‐fold higher in hyposecreting adrenocortical fasciculata cells after one dosage of dexamethasone administration. In addition, the autophagosomes showed a four‐fold decrease in hypesecreting Leydig cells stimulated by LRH for 2 days.Conclusions: Considering that most of the autophagocytosed organelles were steroid‐producing apparatus, we may conclude that, by removing part of steroid‐producing organelles, autophagy might play a role in adapting to or even regulating the secretory activity. This hypothesis was strongly supported by the fact that the intensity of autophagy varied in company with the fluctuation of steroid secretion. © 1995 Wiley‐Liss, Inc.
Growth and turnover of rat otoconia as revealed by labeling with tetracycline
Authors: Kawamata Seiichi , Igarashi Yoshikazu 
Published: February 2005

AbstractBackground: The formation process of otoconia remains controversial, and the turnover rate of mammalian otoconia has not been determined.Methods: Tetracycline was administered as a tracer for calcium, and the growth and turnover of rat otoconia were examined by fluoresence microscopy.Results: Exposure of rats to tetracycline from 15.5 gestational day to 3‐day postpartum resulted in incorporation of the drug into central portions of all otoconia, in both maculae sacculi and utriculi. When postnatal rats were injected subcutaneously with tetracycline, uptake of the drug into otoconia depended on the age of rats at injection. Apparent fluorescence was emitted from the periphery of all otoconia when tetracycline was injected into 7‐day‐old or younger rats. However, very little or no fluorescence was observed when this reagent was administered 10 days after birth. No fluorescence was detected when rats of 12 days of age or older were given this antibiotic. Otoconia that had been labeled with tetracycline during gestation were monitored during subsequent development, and it was found that all otoconia retained labelling in their central portions for at least 12 months. No otoconia that were not labeled with tetracycline were found.Conclusions: These findings indicate that: (1) all otoconia grow synchronously during late gestation and the neonatal period (up to about 10 days after birth) by accretion, (2) no new otoconia are formed subsequently, and (3) essentially no turnover of otoconia occurs and probably no turnover of calcium takes place under normal conditions once otoconia have formed. © 1995 Wiley‐Liss, Inc.
Relationships between endothelial cells, pericytes, and osteoblasts during bone formation in the sheep femur following implantation of tricalciumphosphate‐ceramic
Authors: Decker Brigitte , Bartels Helmut , Decker Sieghard 
Published: February 2005

AbstractBackground: The origin of osteoblasts is still controversial. Whereas several authors consider the stromal fibrablast 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. © 1995 Wiley‐Liss, Inc.
Three‐dimensional organization of the elastic fibres in the rat lung
Authors: Gonçalves Carlos Alberto , Figueiredo Maria Helena , Bairos Vasco António 
Published: February 2005

AbstractBackground: The elastic framework of the distal lung has been studied by light microscopy (LM) and transmission electron microscopy (TEM). The preservation of the elastic fibres, for the three‐dimensional observation in their relative positions, is difficult because they lack support when the normal methods of tissue processing are used. The goal of the present study was to understand the three‐dimensional ultrastructure and organization of the elastic fibres of the lung preserved in their relative positions.Methods: A combination of intravascular resin injection and formic acid digestion was used. The resin cast of the microvasculature acted as a scaffold to preserve the in vivo arrangement of the elastic fibres that are, otherwise, easily collapsible. Scanning electron microscopy (SEM) samples were further processed for TEM in order to confirm that the fibres were indeed components of the elastic system.Results: SEM demonstrated a fine framework of elastic fibres, representing remnants of the alveolar walls, with the casted capillaries interwoven with the network of elastin. Each individual elastic fibre is composed of a small bundle of discrete fibrils. Some of these fibrils emerge from the fibre and join other fibres, producing an anastomosing appearance. Several elastic fibres link the walls of the intrapulmonary conducting airways, the vessels walls and the alveolar network, thus establishing an interrelated and interlaced framework.Conclusions: The method we have applied to visualize the elastic fibres of the lung is a unique approach to define the spatial organization of the pulmonary elastic fibres. We have demonstrated here the close relationship between the elastic fibres and the capillaries of the septal alveoli. The arrangement of the interwoven network of elastin and its relationship with the capillaries offers the structural setting for the distending capacity of the alveolar wall. © 1995 Wiley‐Liss, Inc.