bluuebunny/crossref_metadata_2025_split huggingface dataset:
Estimation of capillary length density in skeletal muscle by unbiased stereological methods: I. Use of vertical slices of known thickness
Authors: Artacho‐Pérula Emilio , Roldán‐Villalobos Rafael 
Published: February 2005

AbstractBackground: The unbiased estimation of the capillary length density in skeletal muscle tissue Lv(cap/mus) has been performed in this study applying a new stereological methodology based on the use of vertical slices and the intersections of cycloid test curves with capillaries in a three‐dimensional space defined by systematically chosen fields of vision and the thickness of the sections.Methods: The following simple requirements must be fulfilled: selection of a fixed vertical axis in skeletal muscle, adequate systematic muscle sampling, obtention of vertical slices of constant and known thickness but indifferent in magnitude, superposition of a cycloid test system with the minor axis of cycloid curves positioned perpendicularly to the vertical axis, and counting the intersections between cycloid curves and capillaries. In our study, the vertical axis was defined as that which is parallel to the natural, major axis of the muscle where fibres and capillaries are arranged parallel to this axis. The muscle sampling was performed using the fractionator method, and 25 pm thick sections were chosen.Results: The application of the equation for estimation of Lv(cap/mus) permits determination of an average of 1,480 mm of capillaries per mm3 of muscle tissue, knowing the number of intersections, section thickness, and the points hitting the muscle with a known ratio between cycloid test curve length to a test point.Conclusions: The estimation of Lv(cap/mus) is efficient, unbiasedly obtained, and no assumption on the degree of capillary anisotropy are required. © 1995 Wiley‐Liss, Inc.
Atrioventricular valves of the mouse: II. Light and transmission electron microscopy
Authors: Icardo José M. , Colvee Elvira 
Published: February 2005

AbstractBackground: Mouse atrioventricular(AV) valves present a number of conspicuous morphologic differences with human AV valves. Given the existence of these differences, it is important to know the structural oranization of mouse AV valves. Since the mouse is often considered to be good animal model for developmental and anatomical studies, the presence of significant difference in structure may render comparative studies difficult. In addition, we wished to learn about the existence of structural changes in the mouse AV valves with age.Methods:The structural organization of mouse AV valves from 21 days to 1 year of age was studied by polarizing microscopy and by conventional light and transmission electron microscopy.Results:Polarizing microscopy reveals the presence of a system of birefringent fibers that consist of collagen bundles that organize like tendons. The spatial organization of these fibers is different in the two AV valves, reflecting differences in the anatomy of the entire valvular complex. Interstitial cells (IC) are of two different phenotypes: some are typical fibroblast, while some others share smooth muscle cell characteristics. In addition, small areas of fibrocartilage are also observed. The compactness and thickness of the collagen bundles increase with age. Also with age, the basement membranes become thickened or multilayered, and matrix vesicles and deposits of amyloid P can be observed.Conclusions:The collagenous birefringent fibers from an internal skeleton that should transmit the cycling stress evenly over the entire leaflets. IC should help to maintain the structure and deformability of the valve tissue and appear actively involved in the synthesis and renewal of extracellular material. The cartilagionous foci appear to be a normal component of the valve tissue. The Structural changes observed in old animals appear to be related to the degenerative processes which take place in normal valvular tissues with age. Despite the structural differeces, age changes appear to be similar in the AV valves of mouse and man. © 1995 Wiley‐Liss, Inc.
Changes in the morphology and phosphatase cytochemistry of the Golgi region of hepatocytes during the acute phase response to inflammation
Authors: Thorne‐Tjomsland Gro , Jamieson James C. 
Published: February 2005

AbstractBackground: During the acute phase response to inflammation, the Golgi apparatus of rat hepatocytes processes an increased quantity of glycoproteins, in the form of acute phase reactants.Methods: The compartmental organization of the hepatocyte Golgi of control and 24 hour inflamed rats was studied, using transmission electron microscopic techniques, including cytochemistry, to detect nicotinamide adenine dinucleotide phosphatase (NADPase), thiamine pyrophosphatase (TPPase), and cytidine monophosphatase (CMPase) activity.Results: In inflamed rats, individual Golgi stacks were enlarged, but retained their organization into four compartments:1) a phosphatase negative, perforated cis‐element, 2) two mid‐saccules which sometimes were positive for NADPase, 3) one or occasionally two NADPase and TPPase positive trans‐saccules, and 4) a tubulovesicular trans‐Golgi network (TGN) which was NADPase reactive and contained a spotty TPPase reaction product. Two of these compartments were noticably altered in response to inflammation. The two mid‐saccules were consistently and uniformly dilated. The TGN was altered to the point of being difficult to recognize and had acquired CMPase reactivity. In control rats the TGN consisted of anastomosing tubules forming cage‐like structures; secretory granules containing lipoprotein particles pinched off from these. In inflamed rats, most of the cage‐like TGN structures had been replaced with an extensive vesicular syncytium which produced secretory granules with a granulofilamentous content.Conclusions: In hepatocytes from inflamed rats an apparent switch had occured in the type of secretory material processed by the Golgi apparatus. Furthermore, the inflammation‐induced increase in the size of individual Golgi stacks apparently was not due to a parallel increase in size of all Golgi saccules. Rather, saccules within given Golgi compartments responded in a characteristic and specific manner to the increase in glycoprotein processing that occurs during inflammation. © 1995 Wiley‐Liss, Inc.
Distribution of somatostatin mRNA containing neurons in the primary pain relaying nuclei of the rat
Authors: Yin Ke‐Jie 
Published: February 2005

AbstractBackground: The spinal trigeminal nucleus and the dorsal horn of the spinal cord are the critical areas in relaying noxious impulses. They also contain large amounts of somatostatin‐like immunoreactivities. Early publications focussed on immunohistochemical studies and were devoid of a detailed description of the distribution of somatostatin in the two nuclei at the molecular level.Method: Frontal tissue sections from the mudulla and the spinal cord of eight rats were examined and a non‐radioactive in situ hybridization histochemical procedure was adopted to study the distribution of somatostatin mRNA positive neurons in the two nuclei.Results: A widespread distribution of somatostatin mRNA containing neurons was shown in the two nuclei at all levels. The positive neuron profiles were normally round or oval in shape and small to medium in size. Three types of cells were identified, which were associated with the intensity of the hybridization signals. The highest density of somatostatin mRNA positive neuron profiles was found in the gelatinous subnucleus at the caudal part of the spinal trigeminal nucleus and in the substantia gelatinosa of the dorsal horn at the levels of the cervical and lumbar cords. Most of them belonged to type I neurons.Conclusions: The present findings are compared to reports of previous studies. It is suggested that somatostatin in the two nuclei may play an important role in the modulation and transmission of pain signals. © 1995 Wiley‐Liss, Inc.
Myelopoiesis in the thymus of the sea bass, Dicentrarchus labrax L. (teleost)
Authors: Avilés‐Trigueros Marcelino , Quesada Juan A. 
Published: February 2005

AbstractBackground: In vertebrates the thymus is primarily regarded as a lymphoid organ whose importance lies in its capacity to produce a large number of lymphocytes that enter the circulation as T cells. In higher vertebrates the organ has also been regarded as a site for my elopoiesis, but this capacity has not been observed in fish. In this study we describe morphologically the presence of intrathymic developing myeloid cells in the sea bass.Methods: The thymus samples were morphologically studied by transmission electron microscopy.Results: We describe the coexistence of cells in different stages of erythropoiesis and granulopoiesis that appear to be developing in situ in some thymus lobes. Degenerated thymocytes and epithelial‐reticular cells occur simultaneously in the same areas.Conclusions: The coexistence of different cellular components of erythropoiesis and the heterophilic series of granulopoiesis with areas of necrosis suggests a relationship between both processes that is influenced by the microenvironment. Our observations also suggest that the presence of intrathymic developing myeloid cells may imply a nonimmunological role for the thymus. © 1995 Wiley‐Liss, Inc.
Pattern of collagen fiber orientation in the ovine calcaneal shaft and its relation to locomotor‐induced strain
Authors: McMahon James M. , Boyde Alan , Bromage Timothy G. 
Published: February 2005

AbstractBackground: Gebhardt (1905. Arch. Entwickl. Org., 20:187–322) originated the hypothesis that the direction of collagen fibers in bone is a structural response to the type of mechanical load to which the bone is subjected. He proposed that collagen fibers aligned parallel to the loading axis are best suited to withstand tensile strain, whereas fibers oriented perpendicular to the loading axis are best able to resist compressive strain. Research comparing load patterns with fiber alignment in bone have tended to support Gebhardt's hypothesis. The aim of the present study is to further test this hypothesis by assessing the correspondence between the distribution of strain and the distribution of collagen fiber orientation in a bone that is subjected to compound loading (i.e., both tension and compression at different phases during the loading cycle). The ovine calcaneum was selected to meet this criterion.Methods: Calcaneum surface strain distributions were obtained from experimental results reported by Lanyon (1973. J. Biomech. 6:41–49). Histological sections of the calcaneal shaft were prepared and observed using circularly polorized light (CPL) microscopy to determine the distribution of collagen fiber alignment. The observed alignment pattern was then compared with the predicted pattern based on Gebhardt's hypothesis.Results: Contrary to previous studies, our findings show no clear correspondence between the strain type of greatest magnitude and the direction of collagen fibers. Areas of bone characterized by high compression and low tension showed predominantly longitudinal collagen alignment (contra to Gebhardt).Conclusions: It is argued that even small magnitudes of tension operating on local areas of bone may be sufficient to induced collagen alignment favorable to this type of strain, even when greater magnitudes of compressive strain are acting on the same bone volume. © 1995 Wiley‐Liss, Inc.
Multinucleated giant cells elicited around hydroxyapatite particles implanted in craniotomy defects are not osteoclasts
Authors: Dersot J. M. , Colombier M. L. , Lafont J. , Baroukh B. , Septier D. , Saffar J. L. 
Published: February 2005

AbstractBackground: The nature of the multinucleated giant cells (MNGC) elicited in contact with implantable biomaterials is still indecisive.Method: In Wistar rats the MNGC recruited after the implantation of hydroxyapatite (HA) particles in standardized skull defects were examined morphologically (at both the light and electron microscope levels), enzymatically (tartrate‐resistant acid phosphatase and non‐specific esterase), and after a challenge with salmon calcitonin.Results: The MNGC were of great size and contained abundant mitochondria, vacuoles, and vesicles throughout the cytoplasm; they were either tightly apposed to the HA surface or had long and thin processes penetrating the material. When processed for tartrate‐resistant acid phosphatase, only a few cells were weakly stained. The staining was totally suppressed when samples were pretreated with cyanuric chloride in the MNGC but not in the host osteoclasts. Calcitonin induced the withdrewal of the host osteoclasts from the bone surface while the MNGC remained in contact with the HA material.Conclusion: The MNGC recruited to HA particles did not exhibit the morphologic, enzymatic and functional characteristics of the osteoclasts, and consequently must be regarded as macrophage polykaryons. © 1995 Wiley‐Liss, Inc.
Chronic corticosterone treatment‐induced ultrastructural changes at rat neuromuscular junction
Authors: Fahim Mohamed A. 
Published: February 2005

AbstractBackground: Chronic exposure to glucocorticoids affects both the structure and function of vertebrate skeletal muscles. As little is known about the effects of such steroids on the neuromuscular junctions (NMJs) of different muscle fiber types, the influence of chronic corticosterone (CORT) administration on the ultrastructure of NMJs of soleus (SOL) and extensor digitorum longus (EDL) was studied.Methods: Ten Fischer 344 male rats, the same animals used previously, were either injected daily with 5–10 mg CORT or received vehicle as control animals for 3 months and were sacrificed at 5 months of age. Muscles were bathed in situ in 4% phosphate buffered glutaraldehyde for ten minutes, then removed and conventional electron microscopic procedures were followed. Qualitative and quantitative observations of nerve terminal ultrastructures were statistically treated with multivariate analysis of variance to determine differences between control and CORT‐treated animals.Results: Fast‐twitch EDL muscles were more affected by CORT‐treatment than slow‐twitch SOL muscles. Morphometric analysis of NMJ's in CORT‐treated rats revealed significant decrease in fiber diameter, nerve terminal area and synaptic vesicle density, but a significant increase in synaptic cleft (P<0.05). The NMJ's underwent partial denervation and reinnervation processes as demonstrated by large areas of presynaptic nerve terminal occupied by microtubules and electron dense granular material.Conclusions: Chronic CORT‐treatments induced degenerative changes which were more pronouced in fast‐twitch EDL muscles than slow‐twitch SOL muscles, suggesting that pattern or amount of activity affect the CORT‐treatment outcome. These steriod‐induced stress changes are similar to those observed in aging and disuse studies of NMJ. Thus, glucocorticoid hormones may play an etiological role in the homeostasis of the NMJ in response to various stimuli. © 1995 Wiley‐Liss, Inc.
Loss of laminin and type IV collagen in uterine luminal epithelial basement membranes during blastocyst lmplantation in the mouse
Authors: Blankenship Thomas N. , Given Randall L. 
Published: February 2005

AbstractBackground: Removal of the uterine luminal epithelium and its basement membrane is necessary for successful implantation of invasive blastocysts. Few reports, however, have specifically addressed the penetration and loss of the uterine luminal epithelial basement membrane (UEBM). We investigated the loss of UEBM by examining the distribution of laminin and type IV collagen.Methods: Blastocyst implantation sites were collected from mice on days 5,6, and 7 of pregnancy. Paraffin sections were prepared from these tissues and processed with standard immunoperoxidase techniques to reveal the distribution of laminin and type IV collagen.Results: On day 5 of pregnancy blastocysts were adherent to the uterine epithelium. The epithelium and UEBM were complete and uninterrupted. On day 6 the juxtaembryonic uterine epithelium was lost and focal discontinuities were seen along the UEBM. By 1200 hr the UEBM had receded to the region near the ectoplacental cone, but staining was reduced for both antigens over the entire region surrounded by decidual cells. This decreased staining of the UEBM occurred in areas not yet occupied by trophoblast cells. On day 7 the UEBM was lost over the entire embryonic half of the uterine lining, corresponding to the distribution of decidual cells.Conclusions: Progressive loss of the UEBM occurred in a consistent spatiotemporal pattern following the onset of blastocyst implantation. Diminished immunoreactivity of laminin and type IV collagen in the UEBM was closely correlated with the area occupied by decidualized endometrial stroma and occurred in areas not yet in contact with trophoblast cells. We conclude that decidual cells are instrumental in the removal of UEBM during early pregnancy. © 1995 Wiley‐Liss, Inc.
In normal development pulmonary veins are connected to the sinus venosus segment in the left atrium
Authors: DeRuiter M. C. , Gittenberger‐De Groot A. C. , Wenink A. C. G. , Poelmann R. E. , Mentink M. M. T. 
Published: February 2005

AbstractBackground: Classic theories descibe that the common pulmonary vein develops as an outgrowth from either the sinus venosus or atrial segment. Recent studies show that the pulmonary veins are connected to the sinu‐atrial region before its differentiation into a sinus venosus and atrial segment.Methods: The development of the sinu‐atrial region with regard to the developing common pulmonary vein and the growth of the atrial septum was investigated in avian embryos, using both scanning electron microscopy and immunohistochemistry. Embryos ranging between stage HH12 and HH28 were incubated with QH‐1 that recognizes quail endothelial cells and precursors, HNK‐1, that appears in this study to detect the myocardium of the sinus venosus, or with HHF‐35, being specific for muscle actins. Also vascular casts of the heart were produced by injecting prepolymerized Mercox into the vascular system.Results: In preseptation stages the common pulmonary vein drains into the left part of the sinus venosus, that is clearly demarcated by the sinuatrial fold and HNK‐1 expression. During atrial septation the left part of the sinus venosus, in contrast to the right part, loses its HNK‐1 antigen from stage HH23 onwards, while at the same time the sinu‐atrial fold in the left atrial dorsal wall flattens and disappears. From stage HH25 onwards HNK‐1 expression is restricted to the right part of the sinus venosus, which contributes to the right atrium. The myocardial atrial septum never expresses the HNK‐1 antigen, suggesting that the septum is of atrial origin.Discussion: It appeared that the sinus venosus does not only contribute to the sinus venarum of the right atrium, but also to the left atrium. © 1995 Wiley‐Liss, Inc.
Ultrastructural quantitative analysis of the innervation of axillary lymph nodes of the rat after antigenic stimulation
Authors: Novotny G. E. K. , Heuer T. , Schötelndreier A. , Fleisgarten C. 
Published: February 2005

AbstractBackground: In a previous study at the LM level we have found an increase in the density of innervation of axillary lymph nodes of the rat 4 months after antigenic stimulation.Methods: To reduce the variability of the results, animals reared under sterile conditions, and stimulated by subcutaneous application of bovine albumin, were used. The control group of animals was compared with three experimental groups surviving the application of antigen for varying periods, so that the ascending phase, the peak, and the descending phase of production of antibodies were represented. The present publication presents the results of the same experiment, but with an ultrastructural analysis of axonal profiles and their spatial relationship to the cells of the lymph node.Results: The present study indicates that, at the ultrastructural level, significant changes occur also during the early phase of the immune response, 10 days after application of antigen. In the short‐term response these changes take the form of an increase in the proportion of unensheathed axonal profiles (open areas) that contain vesicles, a more frequent association of open areas containing vesicles with cells, and an increase in the size of the open areas. In the long‐term reaction there is a general increase in the number of all open areas, but a reduction in the proportion that contains vesicles.Conclusions: Our results demonstrate functional plasticity of the autonomic nervous system in response to normal physiological stimuli, and interaction between the nervous and immune systems during the immune response. © 1995 Wiley‐Liss, Inc.
Special relationship between mitochondria and hypolemmal nerve terminals in salivary glands of some bats
Authors: Tandler Bernard , Phillips Carleton J. 
Published: February 2005

AbstractBackground: Hypolemmal nerve terminals, which are abundant in many types of salivary glands, are naked axons that have penetrated the basement membrane to take up a position between adjacent parenchymal cells. Although they may form vesicle‐filled varicosities, there usually are no obvious morphological indications as to which cell actually is being innervated.Methods: Specimens of over 200 species of bats were live‐trapped and their major salivary glands extirpated and prepared for electron microscopic examination.Results: In 13 species of bats out of the more than 200, mitochondria‐hypolemmal nerve terminal complexes were observed in different sites in different salivary glands. In these 13 species, mitochondria in epithelial cells that abut nerve varicosities are closely applied to the plasma membranes of their cells to follow the contours of these nerve elements. The complexes so formed often consist of a varicosity flanked by two mitochondria in separate cells. In intensely innervated glandular segments, mitochondria may be apposed not only to varicosities, but to the axonal portions of these nervous elements as well.Conclusions: The physiological significance of such complexes is unknown; it is conceivable that the mitochondria facilitate signal transmission or play a role in local calcium homeostasis related to nerve function. © 1995 Wiley‐Liss, Inc.