bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prolonged exposure of human chondrocytes to ascorbic acid modifies cellular behavior in an agarose gel
Authors: Aulthouse Amy Lynn 
Published: February 2005

AbstractUsing an agarose gel culture system, the response of adult human chondrocytes to prolonged exposure of ascorbic acid was evaluated using histochemical, immunocytochemical and morphological techniques. The response of these cells to ascorbic acid was different from those previously reported in the literature. Many chondrocytes branched within the agarose gel with continued exposure to ascorbic acid while other chondrocytes maintained a round configuration typical of chondrocytes in vivo. Fibronectin and type I collagen were closely associated with the cell processes of the branching cells. Type II collagen and an alcian blue‐staining matrix were associated with the rounded cells but not with the branched cells. These data suggest that the chondrocytes are able to express both dedifferentiated and redifferentiated phenotypes with ascorbic acid under these culture conditions. In addition, human chondrocytes were cultured in a collagen gel and began branching within 1 hour of culture. It is possible that an accumulation of type I collagen in the pericellular matrix of ascorbic acid treated cultures may enhance and explain the branching seen in these cultures. Studies by others have indicated that ascorbic acid may enhance, reduce, and/or modify the cartilage matrices produced by chondrocytes. These controversial reports in the literature are presumably due to variations between species and the culture methods employed. © 1994 Wiley‐Liss, Inc.
Cephalic circulation in the air‐breathing snakehead fish, Channa punctata, C. gachua, and C. marulius (ophiocephalidae, ophiocephaliformes)
Authors: Munshi J. S. D. , Roy P. K. , Ghosh T. K. , Olson K. R. 
Published: February 2005

AbstractThe macrocirculation in the head of three air‐breathing species of Channa was examined with the aid of vascular corrosion replicas and a scanning electron microscopic study was conducted on the pseudobranch, choroid gland and lentiform body. Two facultative air‐breathing murrles, C. punctata and C. gachua, and one obligate air‐breather, C. marulius were examined. In all three, the air‐breathing organs (ABO) and systemic circulations were in‐parallel, and both were in‐series with the branchial circulation. Efferent branchial arteries from the first and second gill arches formed the arterial supply to the ABO, whereas the third and fourth arch efferents perfused systemic tissues. Postbranchial blood from the second gill arch also entered the systemic circulation directly via a shunt from the efferent branchial artery to the lateral aorta and via hypobranchial arteries. Vascular specialization to prevent mixing of oxygenated ABO venous and deoxygenated systemic venous blood was evident in arterial, but not venous circuits. Pseudobranchs of C. gachua and C. punctata are tri‐lobed, in C. marulius they have numerous lobules. Pseudobranch lamellae are wider and shorter along the axis of blood flow than gill lamellae and folded perpendicular to this axis. Pseudobranch lamellae appear to be modified to minimize their epithelial surface while retaining an extensive vascular endothelial‐pillar cell surface area, counter‐current amplification is also possible. The choroid gland is an extensive planar counter‐current capillary rete. The lentiform body of the eye is a globular capillary rete but there is no evidence of a counter‐current circulation. The choroid and lentiform rete may have distinct physiological functions. © 1994 Wiley‐Liss, Inc.
Initial vascularisation in the pig placenta: I. Demonstration of nonglandular areas by histology and corrosion casts
Authors: Dantzer Vibeke , Leiser Rudolf 
Published: February 2005

AbstractThe vascular interrelationship of the well‐established porcine placenta has previously been described from vascular casts and histology, but not its developmental stages. This study was peformed using the same methods on 17 sows of well‐known stages of gestation ranging from 9 1/2 to 43 days post coitum (p.c.). At the precontact stage, days 9 1/2 to 12 1/2 p.c., the subepithelial capillaries formed a wide open meshwork of variable diameter, 3–14 μm, without any difference between meso‐ and antimesometrial side. At the early contact and adhesion stages (days 13 to 18 p.c.), the first increase in vasculature was seen at the mesometrial side close to the embryonic disc of the very long blastocyst at day 15 p.c., 2 days after the first contact between trophoblast and maternal epithelium was seen. At day 18 p.c., the areas with dense capillaries increased markedly at the mesometrial side with the same parallel organization as seen at day 15 p.c., whereas the antimesometrial side still had a relative loose appearance comparable to the previous stages. At the early placental stages (days 20 1/2 to 23 p.c.), the capillary bed formed smooth folds, which in some areas at day 20 1/2 days developed into smaller folds or prerugae. Here the capillaries changed to convoluted forms with slightly bulbous dilations measuring about 30–35 μm in diameter. This developmental progress became more elaborate at day 23: capillaries of the low ridges of prerugae formed irregular dilations up to 50 μm in some areas. At this stage the parallel arrangement of the capillary meshwork characteristic of the previous stage was not longer discernable. By days 32–43 p.c., an increase in microscopic folding was present, and the maternal arterioles could be traced to the top of the ridges, creating the characteristic vascular architecture needed for an efficient exchange of oxygen, carbon dioxide, and nutrients of the basically developed porcine placenta. © 1994 Wiley‐Liss, Inc.
Tongue structure and function in Oplurus cuvieri (reptilia: Iguanidae)
Authors: Delheusy Véronique , Toubeau Gérard , Bels Vincent L. 
Published: February 2005

AbstractThe anatomy of the hyo‐lingual apparatus in the iguanid lizard Oplurus cuvieri has been studied by light microscopy and scanning electron microscopy. Four areas were observed on the dorsal lingual epithelium of the lizard. Tongue tips are covered with a smooth epithelium. Closely packed flattened and cylindriform papillae cover the foretongue. The surface of the midtongue bears an unpapillose epithelium. Short conical papillae are arranged on the two lateral posterior bundles of the tongue. At high magnification, microvilli and microridges are widely distributed over the surface of the papillae. The epithelium of the papillae is composed of cells filled with secretory granules. Each surface plays successive roles during food ingestion, intra‐buccal transport, and swallowing. The mucous interpapillary spaces would serve the adherence between the tongue and the food, the smooth epithelium of the midtongue should facilitate movements of the prey toward the pharynx, and conical papillae of the hindtongue present a rough surface which should act on the prey during the swallowing phase. The intrinsic morphology of the tongue is rather similar to that previously described for iguanids, but fibers of M. verticalis encircles ventrally the lingual process. These fibers could act in tongue protrusion as previously suggested for agamids. The morphology and function of the extrinsic tongue musculature and the hyoid musculature, analysed by electrical stimulations, are similar to the previous descriptions in iguanids and agamids either for feeding or displaying functions. © 1994 Wiley‐Liss, Inc.
Subdivision of the mitotic cycle into eleven stages, on the basis of the chromosomal changes observed in mouse duodenal crypt cells stained by the DNA‐specific feulgen reaction
Authors: El‐Alfy M. , Turner J. P. , Nadler N. J. , Liu D. F. , Leblond C. P. 
Published: February 2005

AbstractThe Feulgen reaction has been utilized to localize DNA in nuclei throughout the cycle of mouse duodenal crypt cells using Epon‐embedded 1 μm thick sections. The observed changes indicate that the 12.3 h long mitotic cycle of these cells can be subdivided into eleven stages, seven of which take place during the interphase. Computer measurements of Feulgen‐stained nuclei and previous radioautographic studies indicate that DNA synthesis begins during stage I and ends during stage IV. The staining pattern shows no distinctive feature in the nuclei of the 1.5 h long stage I. Thereafter, marked changes occur during the rest of the interphase—that is during the 6.3 h that precede karyokinesis and the 3.5 h that follow it. Thus, at stage II the background of the nuclei darkens; at stage III, there appear stained threads interpreted as densifying chromosomes and dots interpreted as chromomeres, both of which thicken from 0.2 to 0.4 μm; at stage IV they further thicken to about 0.5 μm and at stage V, to about 0.7 μm. At this stage, which approximately corresponds to prophase, the intensely stained, discrete dots are localized within the less intensely stained sausage‐shaped threads. As the breakup of the nuclear envelope introduces stage VI, whose early part corresponds to prometaphase, the intensely stained dots become close to one another within the threads and eventually fuse. The staining of the threads thus intensifies, and, by the late part of the stage that corresponds to metaphase, they have become the homogeneously dense metaphase chromosomes. At stage VII, the anaphase chromosomes reach each pole where they associate into a compact mass. This mass remains solid at stage VIII but gradually dissociates during stages IX, X, and XI as chromosomes are disassembled. © 1994 Wiley‐Liss, Inc.
Lymphatic capillaries of the pig lung: TEM and SEM observations
Authors: Marchetti C. , Poggi P. , Clement M. G. , Aguggini G. , Piacentini C. , Icaro‐Cornaglia A. 
Published: February 2005

AbstractPulmonary lymphatic vessels extend within the connective tissue sheets surrounding airways and blood vessels. Frequently in this location they also border the lobular parenchyma, but no lymphatic vessels have been found within intralobular compartments between blood capillaries and alveoli. The presence and distribution of lymphatic vessels in pulmonary tissue are consistent with an important role for the lymphatic system in the clearance of interstitial fluids in the lung. Pulmonary lymphatic channels have structural characteristics of initial lymphatics; their walls are formed only by an endothelial layer, and no muscular cells are present. A network of anchoring filaments and collagen and elastic fibers surrounds the vessel walls. Because the lung is a mobile organ the tissue undergoes compression and distension during respiratory phase. These modifications could have a role in the mechanisms for lymph formation and flow. © 1994 Wiley‐Liss, Inc.
Pulmonary hypoplasia associated with reduced thoracic space in mice with disproportionate micromelia (DMM)
Authors: Foster Meredith J. , Caldwell Angela P. , Staheli John , Smith David H. , Gardner John S. , Seegmiller Robert E. 
Published: February 2005

AbstractBackground: Fetal mice homozygous for the Disproportionate micromelia (Dmm) gene were studied as a model for pulmonary hypoplasia in chondrodystrophy.Methods: Wet weight, dry weight, and biochemical content were determined in excised whole lungs, terminal sac morphology and presence of multilamellar bodies were determined by electron microscopy, and volume of the thoracic space was estimated from paraffin casts. Lung development of the mutant was further assessed in whole organ culture.Results. Compared with normal littermates, the mutant showed a significant decrease (28%) in lung wet weight without showing altered lung dry weight or tissue content of DNA and protein. The terminal sacs of lungs fixed by intratracheal instillation were significantly smaller than normal. However, the lungs appeared to have undergone maturation on schedule since the surfactant precursors, multilamellar bodies, were observed and normal tissue‐levels of phospholipid were detected. The volume of the mutant's thorax was markedly reduced. Finally, the mutant's lungs when removed from the fetus prior to the onset of thoracic dystrophy (day 15) and cultured for three days demonstrated that, without the confining influence of a reduced thoracic space, they are capable of development comparable to normal.Conclusions: These findings support the hypothesis that the Dmm mutant can be further studied as a model for human pulmonary hypoplasia associated with chondrodystrophy, and that the relationship between the reduced thorax and the lung disorder is cause‐and‐effect. © 1994 Wiley‐Liss, Inc.
Expression patterns of ammonia‐metabolizing enzymes in the liver, mesonephros, and gut of human embryos and their possible implications
Authors: Dingemanse Maria A. , Lamers Wouter H. 
Published: February 2005

AbstractHuman and ungulate embryos can catabolize amino acids for energy production, whereas rodent embryos cannot, raising the question whether studies of rodent model systems are suitable for extrapolation to the human situation. Therefore, we investigated the expression of the amino acid‐ and ammonia‐metabolizing enzymes glutaminase, glutamate dehydrogenase, glutamine synthase, carbamoylphosphate synthase, and arginase immunohistochemically in a graded series of human embryos and fetuses. During human development the expression of these enzymes is first seen in the liver, then in the mesonephric kidney, and finally in the small intestine. Such a simultaneous expression of nitrogen‐metabolizing enzymes was not seen in any other organ. The early appearance of the enzymes involved in amino acid and ammonia metabolism in the human liver, compared to, for example, the rat liver, suggests that catabolism of amino acids may provide an important supply of metabolic energy for the human embryo. The coexpression of glutaminase, glutamate dehydrogenase, and carbamoylphosphate synthase, but not of arginase, in the mesonephros and the small intestine suggests that these organs are involved in the biosynthesis of intermediates of the ornithine cycle, e.g., arginine or citrulline. From a comparison of the developmental appearance of ornithine cycle enzymes in different mammalian species we postulate that an early appearance of these enzymes is generally associated with a relatively slow prenatal growth rate and the use of amino acids as metabolic fuel. © 1994 Wiley‐Liss, Inc.
Posterior right diagonal artery
Authors: Nerantzis Christos E. , Gribizi Joan E. , Margaris Nikos G. , Antonelis Jhon Pr. , Salahas Tassos I. , Koroxenidis Gabriel T. 
Published: February 2005

AbstractBackground: There is general confusion about a branch of the posterior segment of the right coronary artery that has been referred to as 1) the lower trunk of a divided right coronary artery; 2) a posterior reflection of the right marginal artery; 3) the ramus lateralis; and 4) a posterolateral branch or a posterior descending artery.Materials: Three hundred human hearts were studied by direct observation, X‐ray films, and corrosion casting.Results: This branch of the right coronary artery arises either after the right marginal artery (in 84% of hearts) or it constitutes the continuation of this artery in the remaining 16%. We named it the posterior right diagonal artery (PRDA). It was found in 14% of 266 hearts of right dominant type. It was present in 39% when the length of the posterior descending artery (PDA) was shorter than half of the length of the posterior interventricular sulcus (PIS) and in 6% when it was longer. When the PRDA originated directly from the RCA, the RMA appeared underdeveloped; the PRDA always occupied the inferior part of the PIS and appears either as continuation of a short PDA or as a replacement for a long PDA from the point where this artery leaves the PIS to enter the posterior wall of the left ventricle. The PDRA when present serves as a bridge between the RCA and the left anterior descending artery.Conclusions: These findings are of practical importance for the correct interpretation of coronary arteriographies and in the field of coronary artery surgery. © 1994 Wiley‐Liss, Inc.
Cytochemical characterization of oligosaccharide side chains of the glycoproteins of rat zona pellucida: An ultrastructural study
Authors: Avilés Manuel , Martínez‐Menárguez José Angel , Castells María Teresa , Madrid Juan Francisco , Ballesta José 
Published: February 2005

AbstractBackground: The zona pellucida (ZP), an extracellular matrix which surrounds mammalian oocytes, is formed by different glycoproteins. Several studies have revealed that carbohydrate residues present in glycoproteins of ZP play a key role in the sperm‐egg recognition. However, the origin and the biochemical composition of ZP remain to be completely resolved.Methods: ZP glycoproteins from rat ovarian follicles were investigated at light and electron microscopic level by the application of lectins conjugated to peroxidase, digoxigenin, and colloidal gold in combination with enzyme and chemical treatment. A quantitative analysis was also performed.Results: ZP shows reactivity to WGA, DSA, LFA, AAA, RCA I, and MAA. SBA and PNA showed a variable reactivity ranging from negative to strongly positive. A uniform pattern of binding throughout ZP was observed with DSA, Con A, AAA, MAA, and LFA. However, labeling by RCA I and SBA was higher in the outer ZP while PNA and WGA showed a higher binding in the inner ZP. Lectin reactivity was detected in cortical granules, endoplasmic reticulum, Golgi apparatus, vesicles, and multivesicular bodies of oocytes.Conclusions: ZP contained the terminal disaccharides Galβ1,4GlcNAc, Galβ1,3GalNAc, and GalNAcβ1,3Gal and the trisaccharides Neu5Acα2, 3Galβ1,4GlcNAc, Neu5Ac‐Galβ1,3GalNAc, and Neu5Ac‐GalNAcβ1,3Gal sequences. The occurrence of Fucose residues α 1,6 linked to the inner core region of N‐linked glycoproteins of ZP was demonstratd by the use of several fucose‐specific lectins. Methylation‐saponification treatment in combination with lectin cytochemistry reveals that Gal, GalNAc, and polyllactosamine residues of rat ZP glycoproteins contain sulphated groups. The reactivity observed in ooplasmic vesicles was similar to that of ZP, thus suggesting that the oocyte is the site of synthesis of ZP glycoproteins. © 1994 Wiley‐Liss, Inc.
Collagen fibrils in the odontoblast layer of the rat incisor by scanning electron microscopy using the maceration method
Authors: Tabata Shoji , Nakayama Tsuguhiro , Funakoshi Kimitake , Yasui Kinya , Wada Kaoru , Uemura Masanori 
Published: February 2005

AbstractBackground: There is not universal agreement on the existence of the extracellular pathway from the pulp along the odontoblast layer to the predentin.Method: To confirm this pathway, the architecture of collagen fibrils in the rat incisor dentin and pulp, especially in the odontoblast layer of the lateral (periodontal ligament) sides of the tooth, was demonstrated in the present investigation using scanning electron microscopy of the maceration method for collagen networks.Results: Numerous collagen bundles were observed in the odontoblast layer in the mature odontoblast region which, except for the young odontoblast region, comprises the major portion of the incisor. The collagen bundles went from the pulp, through the odontoblast layer, and were woven into the collagen network of the predentin. The meshwork structure was composed of fine secondary fibrils among these collagen bundles. The surface of the predentin contained many oval‐shaped holes which were surrounded by collagen fibrils. Fracturing the dentin longitudinally relative to the dentinal tubules revealed that the arrangement of the collagen fibrils at the surface of the tubules was either circular or oblique. In the young odontoblast region, i.e., the thin portion from the apical end of the incisor where the mineralization of the dentin does not occur and where the height of the odontoblasts was less than 30 μm, many thick bundles composed of thick collagen fibrils ran straight from the pulp to the predentin through the odontoblast layer and fanned out into the collagen network of the predentin. These thick bundles might correspond to the so‐called “von Korff fibers.” The distribution of collagen fibrils in the pulp was random except on the surface of the blood vessels where the fibrils comprised two sheets of collagen: the inner sheet which coursed longitudinally to the long axis of the vessel, and the outer sheet which ran transversely.Conclusion: It was considered that the fluid in the pulp could flow to the predentin along the collagen fibrils through the tight junction between the odontoblasts. © 1994 Wiley‐Liss, Inc.
Endocrine tissue associated with the pancreatic ductal system: A light and electron microscopic study of the adult rat pancreas with special reference to a new endocrine arrangement
Authors: Bertelli Eugenio , Regoli Mari' , Bastianini Arnaldo 
Published: February 2005

AbstractBackground: A substantial part of the endocrine pancreas has been previously described as being located either close to the excretory ducts as small clusters of endocrine cells and as Islets of Langerhans, or associated with the ducts as single endocrine cells scattered through the ductal epithelium.Methods: Four Wistar white adult rats were sacrificed and perfused via the thoracic aorta with 2.5% glutaraldehyde. After the usual treatment for the transmission electron microscopy, pieces of pancreas were sectioned consecutively for light microscopy. Consecutive ultrathin sections were performed in the most interesting cases.Results: The observations previously reported were confirmed. In addition, a new endocrine arrangement was detected and described as buds of endocrine cells (mainly B‐cells) protruding from the ductal epithelium into the surrounding tissue.Conclusions: The authors propose to explain the endocrine buds as components of the gastro‐entero‐pancreatic system or as a stage of an endocrine pancreatic “neo‐histogenesis” occurring in the adult rat pancreas. © 1994 Wiley‐Liss, Inc.
Morphological studies of hypomineralized enamel of rat pups on calcium‐deficient diet, and of its changes after return to normal diet
Authors: Bonucci Ermanno , Lozupone Enrico , Silvestrini Giuliana , Favia Angela , Mocetti Patrizia 
Published: February 2005

AbstractBackground: Micro‐hardness investigations have shown that rat pups nursed by mothers on a low calcium diet and weaned with the maternal calcium‐deficient diet develop hypomineralized enamel. The inorganic and organic components of this enamel, their relationships, and their changes after return to normal diet have been studied by light and electron microscopy.Methods: The maturation zone of incisor enamel has been studied in: (1) rats nursed for 20 days by mothers on a low calcium diet and weaned for 30 days with the same diet (E1 enamel); (2) rats that after the calcium‐deficient diet were fed normal diet for 10 days (E2 enamel); and (3) rats nursed for 20 days by mothers on a normal diet and weaned for 30 days with a normal diet (controls).Results: The results showed that E1 enamel was hypomineralized, as noted by its Azure II‐Methylene blue stainability in undecalcified sections, its light staining with the von Kossa method, and its ultrastructure. E1 crystallites, although present throughout the whole enamel, were thinner than those of E2 enamel, which were similar to those of controls. E1 interrod crystallites were thicker in the intermediate than in the dentinal zone and were thicker than rod crystallites. Organic matrix was present throughout the whole E1 enamel. Its organic components (crystal ghosts) had the same shape, arrangement, and organization as those of inorganic crystallites. Crystal ghosts were greatly reduced in E2 enamel and in controls.Conclusions: The results lead to the conclusions that: (1) E1 enamel is hypomineralized, and its degree of calcification is restored by return to a normal calcium diet; (2) intra‐ and interprismatic calcification occurs in a different way; (3) crystallite thickness is initially greater in dentinal than in the superficial zone and is reversed as crystallite growth is completed; and (4) loss of enamel proteins is necessary for completion of crystallite growth and not for crystallite formation. © 1994 Wiley‐Liss, Inc.