bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization in the rat spleen of carbon‐laden macrophages introduced into the splenic artery: A subpopulation of macrophages entering the white pulp
Authors: Miyakawa Kazuhisa , Matsuno Kenjiro , Ohmori Jun , Kotani Masahiko 
Published: February 2005

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 is also suggested.
Comparison of the distribution patterns of tenascin and alkaline phosphatase in developing teeth, cartilage, and bone of rats and mice
Authors: Väkevä Liisa , Mackie Eleanor , Kantomaa Tuomo , Thesleff Irma 
Published: February 2005

AbstractTenascin is a glycoprotein of the extracellular matrix, which has been associated with differentiation of hard tissue forming cells. Alkaline phosphatase (AP) is involved in calcification, and it has also been suggested to function in cell differentiation. We have compared the distributions of tenascin and AP in the developing skull and teeth of embryonic and growing rats and mice. Tenascin was localized by immuno‐Peroxidase and AP by enzyme histochemical staining of tissue sections. Both tenascin and AP were largely restricted to bone, cartilage, and teeth. In cartilage, tenascin was expressed in the perichondrium, whereas AP activity was detected only in the hypertrophic cartilage. In growing intramembranous bone, tenascin and AP were expressed in the periosteum and endosteum. AP activity was restricted to the inner layer of the periosteum, whereas tenascin expression extended to the more superficial layers. In bud‐staged teeth tenascin but no AP activity was localized in the condensing mesenchymal cells around the epithelial bud. At the bell stage both tenascin and AP activity were localized in the cuspal mesenchyme, and the intensity of staining decreased towards the cervical region.In summary, tenascin was present at all sites of AP activity except in the epithelial cells of the enamel organ and the hypertrophic cartilage of the mandibular condyle. In mesenchymal tissues tenascin was more widely distributed than AP. It can be suggested that tenascin has functions at earlier stages of hard tissue formation than AP.
Tenotomy‐induced motor endplate alterations in rat soleus muscle
Authors: Pachter Bruce R. , Spielholz Neil I. 
Published: February 2005

AbstractThe effects of tenotomy on the ultrastructure of rat soleus muscle motor endplates were examined both qualitatively and quantitatively. Rat soleus muscle was studied 2 weeks following tenotomy and compared with normal littermates. The motor endplates from the tenotomized muscles were found to exhibit both degenerative and regenerative changes. Degeneration consisted of postjunctional fold breakdown, exposed junctional folds, myelin‐like bodies within the subjunctional sarcoplasm, and dense bodies within the Schwann cell cytoplasm. The regenerative changes consisted of several small nerve terminals occurring within the same primary synaptic cleft and several axons wrapped by the same Schwann cell. The results demonstrate that tenotomy induces denervation‐like changes at endplates that lead to terminal sprouting within the neuromuscular junctional area and remodelling.
Redistribution of membranes and cytoskeletal proteins in chicken oxyntic cells during the HCl secretory cycle: Ultrastructural and immunofluorescence study
Authors: Koenig Cecilia S. , Dabiké Monica 
Published: February 2005

AbstractChanges in ultrastructure and cytoskeletal organization by avian oxyntic cells, at the onset of HCl secretion, were analysed. Cells in resting state, induced by fasting and cimetidine, were compared with histamine stimulated secreting cells. Ultrastructural studies were done by transmission electron microscopy; the distribution of prekeratin, myosin, and filamin‐like protein, by immunofluorescence; and that of F‐actin using FITC‐phalloidin.Resting cells show short pericellular clefts. These are increasingly deepened in secreting cells by a reorganization of the lateral cell borders involving displacement of the junctional complexes toward the cell base and incorporation of the tubular system to the luminal plasma membrane. In secreting cells, the processes of the secretory surface are concentrated in a pericellular groove. Histamine stimulation induces a drastic redistribution of cytoskeletal proteins. In chicken oxyntic cells, in addition to the F‐actin cytoskeleton associated with the membranes of the secretory surface, there is a cytoskeletal ring containing F‐actin, myosin, and a filamin‐like protein, located at the level of the junctional complexes. In resting cells, filaments and masses of cytoskeletal matrix are associated with the zonula adherens. In secreting cells, the junctional complexes maintain their association with the filamentous ring, while the amorphous matrix is replaced by microfilaments that support the processes of the luminal surface. Intermediate filaments form a peripheral ring probably associated with the zonula adherens, and project from the ring toward the cell cytoplasm. Thus, with the onset of HCl secretion, the apical cytoskeletal ring of resting cells displaces toward the cell base. A role for this cytoskeletal ring in the changes in shape parallel to HCl secretion is discussed.
Histochemical, ultrastructural, and electron microprobe analytical studies on the localization of calcium in rat incisor ameloblasts at early stage amelogenesis
Authors: Takano Yoshiro , Yamamoto Tsuneyuki , Domon Takanori , Wakita Minoru 
Published: February 2005

AbstractThe enamel organs of rat incisors were separated from the enamel surface and processed for rapid freezing and freeze‐substitution. A histochemical stain for calcium (GBHA) of thick Epon sections revealed intense calcium reactions in the secretory ameloblasts, exclusively in the tubulovesicular structures extending throughout their distal cytoplasm. Electron microscopy revealed a thin layer of amorphous material with clusters of electron‐dense granules along the distal surface of secretory ameloblasts. In young secretory ameloblasts without typical Tomes' processes, a considerable number of mitochondria were located in the distal cytoplasm and contained numerous electron‐dense granules. Similar dense granules as well as fine ribbon‐like electron‐dense figures, all containing significant amounts of calcium, were observed in some of the tubulovesicular structures at the distal end of these cells. A putative exocytotic figure of such dense granules was also observed. The electron‐dense granules were rare in more differentiated ameloblasts with elongated Tomes' processes, which occasionally displayed ribbon‐like figures in some of the tubulovesicular structures in the process region. No significant calcium peak was detected in the extracellular amorphous material, secretory granules, or along the lateral plasma membranes. These observations may imply high calcium concentrations in mitochondria and tubulovesicular structures in the distal cytoplasm of secretory ameloblasts relative to that of the cytosol and support the possible contribution of these organelles in secretory ameloblasts to cellular calcium regulation at least in the early stage of amelogenesis.
Evidence that apatite crystals of rat incisor enamel have hexagonal cross sections
Authors: Kallenbach Ernst 
Published: February 2005

AbstractImages of nearly cross sectioned enamel crystals obtained with the transmission electron microscope were examined in detail and correlated with various possible cross‐sectional shapes of the crystals. The following images were seen: 1) elongated hexagons with sharp outlines, maximal density, and minimal size (type A profile); 2) elongated hexagons with one pair of long sides of high contrast, two pairs of short sides of low contrast, high density in the center of the image, and low density towards the low contrast sides (type B profile); 3) slanted hexagons with one pair of high contrast sides, two pairs of low contrast sides (one pair of long, one pair of short sides), and the density decreasing from the center towards the low contrast sides (type C profile); this profile was seen more frequently than the type B profile; and 4) octagons with low contrast edges all around, the density decreasing from the center towards the edges (type D profile). Types B, C, and D profiles were larger than type A profiles. Similar crystal images have been described in the literature. When tilting a specimen in increments of 6°, the transformation of type A to type C and type C to type D profiles was observed. Many crystal images did not change their shape greatly when tilting the section through 6°. No rectangular or rhomboidal profiles were seen. It is argued that types A, B, C, and D profiles cannot be generated by apatite crystals with a parallelepiped cross section. They are easily explained, however, on the basis of crystals with hexagonal cross section.
A scanning electron microscopy morphometric study of the rabbit peritoneal surface
Authors: Gaudio Eugenio , Casale Nicoletta , Pannarale Luigi , Priori Alberto , Marinozzi Giulio 
Published: February 2005

AbstractRabbit peritoneum was studied by SEM to obtain information and statistically meaningful morphometric data of different sites of visceral and parietal peritoneum and to verify the existence of “stomata.”Samples were fixed by intraperitoneal infusion of glutaraldehyde, and were photographed by SEM under standard conditions. Morphometric data were obtained by Kontron MOP Videoplan. Variable cell surface patterns were present even within limited areas; however, “stomata” were not observed. The heterogeneity of data obtained can be related to the dynamism of mesothelial cell activity and to the different motilities of the underlying organs.
Impaired development of the thymic primordium after neural crest ablation
Authors: Kuratani Shigeru , Bockman Dale E. 
Published: February 2005

AbstractImpaired thymic development as a result of ablation of neural crest has been observed in embryos late in development. The present study was initiated to determine what changes are effected early in thymic development by neural crest ablation. The epithelial primordia of the thymus were studied in chick embryos on the sixth day of incubation. Embryos with neural crest ablations were compared with sham‐operated and untreated controls. Neural crest ablation inhibited formation of epithelial thymic primordia. Primordia in experimental embryos were fewer in number and were smaller than in shams and untreated controls. When primordia from shams and controls were transplanted to the chorioallantoic membrane of chick hosts, they were able to develop into organs with the typical features of embryonic thymus. Similar transplantation from neural crest‐ablated animals, on the other hand, led to small, predominantly epithelial structures with meager lymphoid development. These findings are consistent with the hypothesis that mesenchyme derived from cranial neural crest is critical in initiating and sustaining the development from pharyngeal pouches of epithelial structures competent to attract and support the proliferation and differentiation of lymphoid stem cells.
Myotome and early neurogenesis in chick embryos
Authors: King Earl D. , Munger Bryce L. 
Published: February 2005

AbstractThe present study was undertaken in order to verify the identification of profiles of presumptive growth cones in vivo. The developing spinal nerves of chick embryos were studied by light and electron microscopy. We traced the onset of efferent and afferent innervation of the myotome in 2‐ to 4‐day‐old chick embryos in order to be sure that we were examining the growing tips of axons. In the process of studying these growing axons, we were able to observe some unique relationships of neural tube, myotome, and differentiating spinal nerves. The neural tube tightly abuts the myotome in Hamburger and Hamilton's (HH) stage 14 chick embryos and cytoplasmic projections from the myotome directly abut the neural tube. The first ventral roots could be identified in HH stage 15 embryos and dorsal roots in HH stage 16 embryos, both under 2½ days of age. The advancing spinal nerve courses toward the anterior or cranial half of the myotome, and growth cones directly contact the medial wall of the myotome. The spinal nerves continue to abut tightly the myotome during the succeeding day of embryonic life, and growth cones enter the substance of the myotome by 3 days, or HH stage 19 embryos. These dorsolaterally directed axons will form the dorsal ramus of the spinal nerves and the ventral ramus continues to be contiguous with the myotome. Invasion of the myotome by axons (putative innervation), and thus innervation of myotomal cells in the 3‐day chick embryos, was a totally unexpected finding. The myotome and its potential derivatives thus have extensive neural contact by 3 days of embryonic life in the chick. These findings document a parallel differentiation of afferent and efferent elements of the nervous system and confirm previous accounts identifying growth cones in an intact organism. These findings suggest that afferent as well as efferent nerves may have critical roles in the differentiation of the mesodermal as well as ectodermal derivatives.
Stage‐dependent spontaneous frog dorsal root ganglion neuritogenesis on polylysine in vitro
Authors: Pollack Emanuel D. , Liebig Veronica 
Published: February 2005

AbstractDorsal root ganglia of larval frog extended elaborate neuritic arrays in vitro under minimal culture conditions in the absence of medium‐supplemented stimulatory factors. The highly adhesive attachment substratum polylysine provided the necessary condition for exuberant outgrowth, the extent of which was dependent on the developmental stage of the animal from which the neural tissue was derived, as was the capability for long‐term survival. It appears that an appropriate substratum can substitute for added growth factors in eliciting robust and long‐lived sensory neurites in vitro.
Myosin isozyme expression in response to stretch‐induced hypertrophy in the Japanese quail
Authors: Matthews William , Jenkins Robert R. , Gonyea William J. 
Published: February 2005

AbstractWhen skeletal muscle is subjected to stretch it undergoes a rapid increase in muscle mass. However, the effect of stretch on the native myosin isozyme content of muscle has received attention only recently. Using the Japanese quail to investigate stretch‐induced hypertrophy, we demonstrated an increase in the expression of fast myosin in the predominantly slow anterior latissimus dorsi muscle (ALD). The fast myosin content of the control quail ALD is not sufficient to be quantified on native myosin pyrophosphate gels. After 33 days of stretch, the fast myosin content (N = 10) averaged 16 ± 11% in the stretched muscles and reached a maximum of 40%. Mean hypertrophy in the stretched muscle, as indicated by muscle weight, was 247 ± 91%; (range, 168–378%). Fast myosin was consistently expressed in muscles with hypertrophy greater than 250%. Muscle fiber size from the stretched muscles contained a greater number of fibers with small cross‐sectional areas than was observed in controls. These results indicate that substantial remodeling occurs in the stretched ALD muscle of the Japanese quail.
Effects of temperature and buffer composition on calcium sequestration by sarcoplasmic reticulum and plasma membrane of rabbit renal artery
Authors: McGuffee Linda J. , Little Sally A. , Mercure Juanita V. , Skipper Betty J. , Wheeler‐clark Ellyn S. 
Published: February 2005

Abstract45Ca electronicroscopic autoradiography was used to examine the effects of buffer composition and temperature on the distribution of calcium in rabbit renal artery smooth muscle cells. The results show that the relative distribution of calcium is dependent on both the buffer used (Tris or Krebs) and the temperature of the bathing solution (25°C or 34°C). Krebs buffer at 34°C gave the highest relative activity in the plasma membrane, sarcoplasmic reticulum, and mitochondria. Buffer and temperature had little effect on the relative activity of the nucleus or cytoplasm. Next, we identified the cellular sites of calcium accumulation after 5, 15, 30, or 60 min exposure to 45Ca in Krebs buffer at 34°C. The results show that sarcoplasmic reticulum and plasma membrane are the primary sites of calcium accumulation during influx into these cells. Although the amount of 45Ca in the cell continues to increase with longer exposure, the relative distribution of calcium is essentially the same after 5 or 60 min. The data also indicate that the relative activity of plasma membrane + sarcoplasmic reticulum (a combination site that includes sarcoplasmic reticulum within a mean distance of 275 nm of the plasma membrane) is similar to the membrane alone and is lower than the sarcoplasmic reticulum alone.
Functional, physical, and ultrastructural localization of CD15 antigens to the human polymorphonuclear leukocyte secondary granule
Authors: Buescher E. S. , Livesey S. A. , Linner J. G. , Skubitz K. M. , McIlheran S. M. 
Published: February 2005

AbstractA murine monoclonal IgM antibody, M3, which interferes with both polymorphonuclear leukocyte (PMN) phagocytosis and bactericidal activity, was used to examine the subcellular location of antigens bearing 3‐fucosyllactosamine (CD15 antigens) within this cell type. Percoll gradient‐separated secondary granule fractions were rich in CD15 antigens, with at least seven antigens recognizable in SDS‐PAGE/electroblot studies. Sonication/sedimentation experiments using secondary granule fractions showed that both soluble and sediment‐able CD15 antigens were present. Exposure of purified PMN to the secondary granule secretagogue phorbol myristate acetate caused extracellular release of two or three CD15 antigens, which could be purified by immunoprecipitation using antibody M3. Triton X‐114 phase‐partition experiments showed that secondary granule fraction CD15 antigens could be partitioned into hydrophilic (aqueous phase) and hydrophobic (detergent phase) antigens, suggesting that several of these antigens were integral secondary granule membrane components. Ultra‐structurally, PMN intracellular granules showed two patterns of CD15 expression, localization over both granule matrix/granule membrane and localization to only granule membrane. Colocalization studies showed that lactoferrin and CD15 antigens were both present in a subset of intracellular granules, confirming a secondary granule location for these antigens.
Blisters in the area pellucida, area opaca, and segmental plate of avian embryos
Authors: Lash James W. 
Published: February 2005

AbstractThis is a special communication in an area of special interest to all researchers using avian material. Avian embryos in the Northeast, representing four species (chicken, quail, duck, guinea hen), have been found to be drastically deficient in presomitic tissue (segmental plate tissue) between 45 and 60 h of incubation. These deficiencies first appear in the embryo as blisters, then, through tissue repair, they disappear and the embryos continue seemingly normal development. Similar blisters and excrescences appear in the area pellucida and area opaca between 20 and 30 h of incubation. Associated with these blisters and excrescences in very young embryos and blisters in segmental plates, but not necessarily the result of them, is a high incidence of congenital malformation during later development. These anomalies may be affecting the results obtained in avian research.
Elastin in human, baboon, and mouse liver: An immunohistochemical and immunoelectron microscopic study
Authors: Porto Luis CristóVão , Chevallier Michèle , Peyrol Simone , Guerret Sylviane , Grimaud Jean‐Alexis 
Published: February 2005

AbstractLight microscope histochemistry and immunohistochemistry, and routine electron microscopy techniques were performed to analyse elastin distribution and structure in the human liver compared with that in baboon and mouse. In man and baboon, elastic fibers stained by iron hematoxylin or orcinolnew fuchsin seemed to be solitary and were few in number; in the mouse they were thinner but abundant, both in the portal tract and in hepatic veins. Orcein or resorcin‐fuchsin stains, employed after oxidation of tissue sections, revealed a network comprising elastic, elaunin, and oxytalan fibers, which was also demonstrated by immunofluorescence with anti‐elastin antibody in man and baboon. At the ultrastructural level, the elastic fibers of the human portal tract corresponded to discontinuous patches of amorphous material intermingled with few microfibrils. These contrasted with the thinner elastic fibers of baboon and mouse liver which had a core of amorphous material. In man and baboon, these fibers meshed into slender bundles of microfibrils often exhibiting small spots of amorphous material (elaunin fibers) and terminated as isolated microfibrils (oxytalan fibers). Immunoelectron microscopy of elastin carried out on baboon liver tissue labelled the amorphous material and also its microfibrillar component. Immunoperoxidase deposits were also associated with isolated bundles of microfibrils in the baboon portal stroma. Immunolabelling and elastic stains disclosed an important elastin portal network located around vascular, biliary structures and interspaced with collagen bundles. The structural polymorphism of elastin, assembling different relative amounts of amorphous material and microfibrils, might have a relationship with the required elasticity in a given species.