Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 15 of 15
Full-Text Articles in Entire DC Network
Patterns Of Calcium Oxalate Crystal Production By Three Species Of Wood Decay Fungi, Jon H. Connolly, Howard J. Arnott, Jody Jellison
Patterns Of Calcium Oxalate Crystal Production By Three Species Of Wood Decay Fungi, Jon H. Connolly, Howard J. Arnott, Jody Jellison
Scanning Microscopy
Wood decay experiments using red spruce wood resting on moist soil were conducted to discern temporal and spatial patterns of calcium oxalate (CaOx) crystal production by three species of fungi over the course of decay. All three species produced crystals of calcium oxalate dihydrate, but not monohydrate, in and on wood. Over the course of decay, the production of CaOx crystals was shown to be heterogeneous in both space and time. The relative quantity, morphology and longevity of CaOx crystals varied among species. Gloeophyllum (G.) trabeum produced substantial quantities of "free" crystals; Fomitopsis (F.) pinicola produced encrusting crystals; and Trichaptum …
Effects Of Ionizing Radiation On Cartilage: Emphasis On Effects On The Extracellular Matrix, M. Cornelissen, H. Thierens, L. De Ridder
Effects Of Ionizing Radiation On Cartilage: Emphasis On Effects On The Extracellular Matrix, M. Cornelissen, H. Thierens, L. De Ridder
Scanning Microscopy
In this report, we review data dealing with radiation effects on cartilage. More specifically, we emphasize on alterations caused in the extra-cellular cartilage matrix. Although radiation studies predominantly describe the effect on the structure of DNA and on the mitotic activity of cells, alterations caused by the effect on the non-mitotic activity can also be important. Cartilage, having an extracellular matrix composed of 2 major components, aggrecan and collagen, provides a good model to study this kind of radiation effects. The following topics concerning literature data are summarized: effects on the amount of matrix synthesized, effects on the activity of …
Cell Death In The Embryonic Developing Limb, J. M. Hurle, M. A. Ros, V. Garcia-Martinez, D. Macias, Y. Ganan
Cell Death In The Embryonic Developing Limb, J. M. Hurle, M. A. Ros, V. Garcia-Martinez, D. Macias, Y. Ganan
Scanning Microscopy
In amniote vertebrates, the development of form and structure of the limb bud is accompanied by precise patterns of massive mesodermal cell death with morphological features of apoptosis. These areas of cell death appear to eliminate undifferentiated cells which are required only for a limited time period of limb development. Predictable skeletal and morphological anomalies of the limb occur when the pattern of cell death is modified in mutant species or under experimental conditions. Most evidence points to the occurrence of local triggering mechanisms to account for the establishment of the areas of cell death and the subsequent activation of …
Ultrastructure Of Dentin Matrix In Heritable Dentin Defects, J. Waltimo, H. Ranta, P. -L. Lukinmaa
Ultrastructure Of Dentin Matrix In Heritable Dentin Defects, J. Waltimo, H. Ranta, P. -L. Lukinmaa
Scanning Microscopy
Heritable dentin defects form a group of diseases which exclusively affect dentin among the various dental tissues. While one type is associated with the generalized connective tissue disorder, osteogenesis imperfecta, other types occur as single traits. The clinical manifestations of the dentin defects vary from insignificant to severe enough to cause aesthetical and functional failure of the teeth. Scanning and transmission electron microscopic studies, reviewed in this paper, have markedly clarified the ultrastructure of the aberrant dentin matrix. Both similar and different changes seem to occur in the various forms of heritable dentin defects. Abnormalities in the appearance and organization …
Cellular Interactions In Hemopoietic Progenitor Cell Homing: A Review, Cheryl L. Hardy, Jose J. Minguell
Cellular Interactions In Hemopoietic Progenitor Cell Homing: A Review, Cheryl L. Hardy, Jose J. Minguell
Scanning Microscopy
Within the bone marrow microenvironment, dynamic cellular interactions are constantly occurring. These interactions involve hemopoietic stem cells, progenitor cells and maturing cells, physically interacting with other cells, some of which may function as accessory cells, and others which comprise the stromal elements; hemopoietic cells also interact with non-cellular elements, such as glycoproteins and fibrous proteins of the extracellular matrix (ECM). These interactions serve to regulate normal hemopoiesis by allowing the communication of regulatory information, migration and subsequent homing of stem cells within specific organs, and presentation of hemopoietic growth factors in a biologically relevant fashion. The goal of this review …
Studies Of Heart Development In Normal And Cardiac Lethal Mutant Axolotls: A Review, M. E. Fransen, L. F. Lemanski
Studies Of Heart Development In Normal And Cardiac Lethal Mutant Axolotls: A Review, M. E. Fransen, L. F. Lemanski
Scanning Microscopy
The morphology of developing hearts in axolotls, Ambystoma mexicanum, has been studied by scanning electron microscopy in order to provide a chronology of morphogenesis that can be correlated with ongoing biochemical and immunocytochemical studies. In addition to normal embryos we have studied homozygous recessive cardiac lethal mutant axolotls. The mutant myocardium undergoes aberrant sarcomere development and lacks a normal heartbeat. Morphogenesis of mutant hearts appears to be nearly normal with respect to myocardial cell shape changes, epicardial formation, and the distribution of extracellular matrix fibrils in the cardiac jelly. This suggests that the deficient arrangement of contractile proteins in …
Microprobe Analysis Of Element Distribution In Bovine Extracellular Matrices And Muscle, M. B. Engel, H. R. Catchpole
Microprobe Analysis Of Element Distribution In Bovine Extracellular Matrices And Muscle, M. B. Engel, H. R. Catchpole
Scanning Microscopy
The concentrations of some essential elements, Na, K, P, S and Cl were determined by microprobe analysis in bovine extracellular matrices of cartilage, tendon and elastic tissue (ligamentum nuchae) and in muscle cells. The values for the different tissues were compared and related to the blood electrolyte concentrations. Among the connective tissues the highest Na and lowest Cl values were found for cartilage which bears a high negative charge. The lowest concentrations of these elements occurred in elastic tissue which is relatively non-polar. In the three extracellular matrices sodium levels exceeded potassium. In myofibers potassium was the major cation at …
Effects Of Extracellular Matrix On Cytoskeletal And Myofibrillar Organization In Vitro, Lula L. Hilenski, Louis Terracio, Roger Sawyer, Thomas K. Borg
Effects Of Extracellular Matrix On Cytoskeletal And Myofibrillar Organization In Vitro, Lula L. Hilenski, Louis Terracio, Roger Sawyer, Thomas K. Borg
Scanning Microscopy
The distribution and three-dimensional relationship of myofibrillar and cytoskeletal components during myofibrillogenesis were examined in preparations of neonatal rat cardiac myocytes processed in parallel for scanning electron microscopy (SEM), intermediate voltage transmission electron microscopy (IVEM) and immunofluorescence (IF). Of the various methods used for processing, optimal results were achieved by pre-extraction with Triton X-100 in an actin-stabilizing buffer. This procedure effectively removed the surface membrane, as viewed by SEM images, while preserving myofibrillar and cytoskeletal structure, as evidenced by IF for actin, 𝝰-actinin and vinculin. Cytoskeletons in SEM images consisted of a cortex of anastomosing filaments through which ran parallel …
Extracellular Matrix Production By Osteoblasts On Bioactive Substrata In Vitro, J. E. Davies, T. Matsuda
Extracellular Matrix Production By Osteoblasts On Bioactive Substrata In Vitro, J. E. Davies, T. Matsuda
Scanning Microscopy
Some bone-substitute biomaterials have been classified as bioactive since they allow direct biological bonding to their surface in vivo. Using in vitro techniques, we have re-created the first stages of this biological bonding phenomenon and compared the initial, fibrillar, extracellular matrices produced by migrated primary osteoblast cell populations in contact with both dense and macroporous calcium phosphate substrata, apatite/bioactive glass composite (ABC) and 45S5 bioactive glass (BAG). The first formed fibrils in contact with these materials may be identified as collagen from their morphology as observed by scanning electron microscopy (SEM). However, the organization of this fibrillar material is …
Somites And Axon Guidance, Kathryn W. Tosney
Somites And Axon Guidance, Kathryn W. Tosney
Scanning Microscopy
The somites are arrayed in a repeating pattern along the longitudinal axis of the embryo, as are the developing sensory and sympathetic ganglia and the spinal nerves. This pattern is not a coincidence: the somite imposes a segmental pattern on the cells and axons that invade it. Both neural crest cells and axons prefer the anterior portion of the sclerotome (the ventral part of the somite) for outgrowth. What differences in anterior and posterior sclerotome are responsible? I used scanning electron microscopy to ask whether these populations differed on the tissue level in chick embryos. This study shows that differences …
Early Cardiogenesis In The Newt Embryo, R. Hirakow, S. Komazaki, T. Hiruma
Early Cardiogenesis In The Newt Embryo, R. Hirakow, S. Komazaki, T. Hiruma
Scanning Microscopy
The migration of cardiogenic cells and the formation of a tubular heart in newt embryos were examined mainly by scanning electron microscopy (SEM). Cardiogenic cells are known to localize at the border region of lateral mesoderm migrating in the space between the ectoderm and the endoderm. They initially (before stage 20 or mid-neurula) appeared to attach to the basal surface of the ectoderm, whereas later (after stage 22 or late neurula) they changed their scaffold to the endoderm. On the scaffold cell surface, very fine fibrils of extracellular matrix (ECM) were found. These fibrils were proved to be composed partly …
Assembly And Alignment Of Fibronectin-Coated Gold Beads Into Fibrils By Human Skin Fibroblasts, Donna M. Pesciotta Peters, Deane F. Mosher
Assembly And Alignment Of Fibronectin-Coated Gold Beads Into Fibrils By Human Skin Fibroblasts, Donna M. Pesciotta Peters, Deane F. Mosher
Scanning Microscopy
The assembly of fibronectin into fibrils was monitored by high voltage electron microscopy using 18 nm colloidal gold beads bound to fibronectin (Au18-fibronectin) or an amino terminal 70 kd fragment of fibronectin (Au18-70 kd) that blocks the incorporation of fibronectin into disulfide bonded fibrils. Subconfluent cultures of human skin fibroblasts were incubated with the colloidal gold complexes for 0.25, 0.5, 1.5 and 5 h. In fibroblast cultures incubated with Au18-fibronectin and Au18-70 kd fragments for 0.25 and 0.5 h, the complexes of Au18-fibronectin and Au18-70 kd fragment were …
Adhesion, Spreading And Fragmentation Of Human Megakaryocytes Exposed To Subendothelial Extracellular Matrix: A Scanning Electron Microscopy Study, Y. G. Caine, I. Vlodavsky, M. Hersh, A. Polliack, D. Gurfel, R. Or, R. F. Levine, A. Eldor
Adhesion, Spreading And Fragmentation Of Human Megakaryocytes Exposed To Subendothelial Extracellular Matrix: A Scanning Electron Microscopy Study, Y. G. Caine, I. Vlodavsky, M. Hersh, A. Polliack, D. Gurfel, R. Or, R. F. Levine, A. Eldor
Scanning Electron Microscopy
Platelet agonists and subendothelial extra-cellular matrix (ECM) induce morphological and biochemical changes in animal megakaryocytes, reminiscent of the response of platelets to the same substances. We have examined the behavior of human megakaryocytes exposed for up to 36 hours to the ECM produced by cultured bovine corneal endothelial cells. By phase contrast and scanning electron microscopy these megakaryocytes demonstrated non-reversible adherence and flattening with formation of long filopodia, thus confirming that human megakaryocytes acquire platelet functional capacities. In addition, megakaryocyte fragmentation into prospective platelets was apparently induced by the ECM. Up to 50% of the adherent megakaryocytes underwent spontaneous fragmentation …
The Migration Of Amphibian Primordial Germ Cells In The Chick Embryo, Marjorie A. England, Alma P. Swan, P. Dane
The Migration Of Amphibian Primordial Germ Cells In The Chick Embryo, Marjorie A. England, Alma P. Swan, P. Dane
Scanning Electron Microscopy
A fibrous band of extracellular materials on the chick embryo area pellucida/area opaca border is a preferential migratory pathway for chick embryo primordial germ cells (PGC). This band contains fibronectin, collagen Type I and sulphated glycosaminoglycans. It is known that PGCs from Xenopus laevis interact with fibronectin as they undergo migration in the embryo from their site of origin to the gonads. To establish whether this pathway is species specific in chick embryos it was decided to transplant PGC from Xenopus laevis embryos stage 48 on to chick embryos stage 4 fibrous band. Their rapid migration on this extracellular matrix …
Cell Movement And Contraction In Somite Development, Ellen A. G. Chernoff
Cell Movement And Contraction In Somite Development, Ellen A. G. Chernoff
Scanning Electron Microscopy
During somite formation the segmental plate mesoderm, lying on either side of the axial organs, reorganizes into roughly spherical pairs of epithelial structures. This segmentation process includes changes in cell shape and position, cell-cell and cell-substratum adhesive properties and accumulation of extracellular matrix material which proceed down the anterior-posterior axis. Later in somite development the sclerotome region "disperses", migrating around the spinal cord where it produces the cartilage model of the vertebral column. Experimental manipulation of segmentation and sclerotome dispersal with drugs affecting microfilaments, microtubules and calcium-dependent contraction suggest that cells migrate into position, elongate, and undergo apical contraction as …