Home About us Contact
|
Home About us Contact | ||
|
|
||
Morphological Aspects (morphological + aspect)
Selected AbstractsMorphological Aspects of In Vivo Cleavage in Myocastor coypus (coypu)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 2 2004A. E. Felipe Summary The objective of the present work was to characterize the in vivo cleavage stage of Myocastor coypus embryos. For this purpose a colpocytological follow-up and controlled mating of 18 females were performed. Specimens from the beginning of the first cleavage to the acquisition of a morula appearance were considered to be in cleavage stage. Embryos in cleavage were collected between days 3 and 6 post-coitus. Of the collected embryos, 80% presented an even number of blastomeres and the remaining 20% an odd number. Embryos from 3 to 7 cells were blastomere associations in a spherical disposition within the zona pellucida. Blastomeres were spherical or ovoid, presenting slight flattening in areas contacting with other blastomeres. Embryos of 8 and 9 cells were as a group of blastomeres slightly elongated, surrounded by a spherical zona pellucida. The percentage of peri-vitelline space occupied by the embryonic mass ranged from 74.1 to 95.8% for all the substages. The cleavage pattern, developed in the oviduct, was of a rotational holoblastic type and asynchronic. [source] Nanocrystalline non-planar carbons: Growth of carbon nanotubes and curled nanostructuresCRYSTAL RESEARCH AND TECHNOLOGY, Issue 10-11 2005S. Orlanducci Abstract We present a variety of non-planar graphitic nanostructures selectively generated in a modified Hot-Filament Chemical Vapour Deposition (HF-CVD) apparatus, using purpose-synthesized amorphous carbon nanoparticles or graphite powders as solid state precursor. The employed methodologies enable to successfully synthesize homogeneous and well organized deposits of single- and multi-walled carbon nanotubes, onion-like nanostructures, and nanotube bundles coated by nano-sized diamond grains. Variations in the morphological aspect of such non-planar graphite-based nanostructures are observed changing the experimental conditions: the solid state reactants, the filament and substrate temperatures, the catalyst concentration, and the atomic hydrogen flux over the substrate play key roles in the phenomenon. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Liver sinusoidal endothelial cells and acute non-oxidative hepatic injury induced by Pseudomonas aeruginosa pyocyaninINTERNATIONAL JOURNAL OF EXPERIMENTAL PATHOLOGY, Issue 6 2008Rajkumar Cheluvappa Summary The liver sinusoidal endothelial cell (LSEC) is damaged by many toxins, including oxidants and bacterial toxins. Any effect on LSECs of the Pseudomonas aeruginosa virulence factor, pyocyanin, may be relevant for systemic pseudomonal infections and liver transplantation. In this study, the effects of pyocyanin on in vivo rat livers and isolated LSECs were assessed using electron microscopy, immunohistochemistry and biochemistry. In particular, the effect on fenestrations, a crucial morphological aspect of LSECs was assessed. Pyocyanin treatment induced a dose-dependent reduction in fenestrations in isolated LSECs. In the intact liver, intraportal injection of pyocyanin (11.9 ,M in blood) was associated with a reduction in endothelial porosity from 3.4 ± 0.2% (n = 5) to 1.3 ± 0.1% (n = 7) within 30 min. There were decreases in both diameter and frequency of fenestrations in the intact endothelium. There was also a decrease in endothelial thickness from 175.8 ± 5.8 to 156.5 ± 4.0 nm, an endothelial pathology finding previously unreported. Hepatocyte ultrastructure, liver function tests and immunohistochemical markers of oxidative stress (3-nitrotyrosine and malondialdehyde) were not affected. Pyocyanin induces significant ultrastructural changes in the LSEC in the absence of immunohistochemical evidence of oxidative stress or hepatocyte injury pointing to a novel mechanism for pyocyanin pathogenesis. [source] Development of the endoderm and gut in medaka, Oryzias latipesDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 5 2006Daisuke Kobayashi We performed an extensive analysis of endodermal development and gut tube morphogenesis in the medaka embryo by histology and in situ hybridization. The markers used in these analyses included sox17, sox32, foxA2, gata-4, -5, -6 and shh. sox17, sox32, foxA2, and gata-5 and -6 are expressed in the early endoderm to the onset of gut tube formation. Sections of medaka embryos hybridized with foxA2, a pan-endodermal marker during gut morphogenesis, demonstrated that gut tube formation is initiated in the anterior portion and that the anterior and mid/posterior gut undergo distinct morphogenetic processes. Tube formation in the anterior endoderm that is fated to the pharynx and esophagus is much delayed and appears to be independent of gut morphogenesis. The overall aspects of medaka gut development are similar to those of zebrafish, except that zebrafish tube formation initiates at both the anterior and posterior portions. Our results therefore describe both molecular and morphological aspects of medaka digestive system development that will be necessary for the characterization of medaka mutants. [source] Structure, lymphatic vascularization and lymphocyte migration in mucosa-associated lymphoid tissueIMMUNOLOGICAL REVIEWS, Issue 1 2003Giacomo Azzali Summary:, In this review, we consider the morphological aspects and topographical arrangement of gut-associated lymphoid tissue (GALT) (solitary and aggregate lymph nodules or Peyer's patches) and of vermiform appendix in the human child and in some mammals. The spatial arrangement of the vessels belonging to apparatus lymphaticus periphericus absorbens (ALPA) and of blood vessels within each lymphoid follicle as well as the ultrastructural characteristics of the lymphatic endothelium with high absorption capacity are considered. Particular attention is also paid to the morphological and biomolecular mechanisms inducing lymphocyte transendothelial migration to the bloodstream by means of lymphatic vessels as well as their passage from blood into lymphoid tissue through the high endothelial venules (HEVs). The preferential transendothelial passage of lymphocytes and polymorphonuclear neutrophils within ALPA vessels of the interfollicular area does not occur following the opening of intercellular contacts, but rather it occurs by means of ,intraendothelial channels'. In HEVs, on the contrary, the hypothesis is plausible that lymphocyte transendothelial migration into lymphoid tissue occurs through a channel-shaped endothelial invagination entirely independent of interendothelial contacts. The lymph of ALPA vessels of the single Peyer's patch is conveyed into precollector lymphatic vessels and into prelymph nodal collectors, totally independent of the ALPA vessels of the gut segments devoid of lymphoid tissue. The quantitative distribution of T lymphocytes in the lymph of mucosal ALPA vessels suggests a prevalent function of fluid uptake, whereas a reservoir and supply function is implicated for the vessels of interfollicular area. The precollector lymphatic vessels and prelymph nodal collectors are considered to be vessels with low absorption capacity, whose main function is lymph conduction and flow. [source] Examination of whewellite kidney stones by scanning electron microscopy and powder neutron diffraction techniquesJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2009Michel Daudon Kidney stones made of whewellite, i.e. calcium oxalate monohydrate, exhibit various morphological aspects. The crystalline structure of whewellite at the atomic scale was revisited through a single-crystal neutron study at room temperature using a four-circle automated diffractometer. The possible relationships between the various morphological types of whewellite stones and their structural characteristics were examined at the mesoscopic scale by the use of scanning electron microscopy and at the nanometric scale by powder neutron diffraction. All types of whewellite stones displayed a similar structure at the nanometric scale. However, significant differences were found at the mesoscopic scale. In particular, the crystallites in kidney stones resulting from a genetic hyperoxaluria exhibited a peculiar structure. There was a close relationship between stone morphology and crystallite organization at the mesoscopic level and the effectiveness of extracorporeal shockwave lithotripsy. [source] The influence of the acidic component of the gas-foaming porogen used in preparing an injectable porous calcium phosphate cement on its properties: Acetic acid versus citric acidJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2008Saeed Hesaraki Abstract In the present study, macroporous calcium phosphate cements (CPCs) were prepared using a porogen; that is, the gas-foaming technique. The objective was to investigate the influence of the acidic component of the porogen (acetic acid versus citric acid) on several properties of a specified CPC. In all of the cements prepared, the basic component of the porogen was the same, namely, NaHCO3, and it was added to the powder phase of the cement, while the acidic component of the porogen was dissolved in the liquid phase of the cement. The cements were characterized in terms of initial setting time, porosity, crystallinity, injectability and compressive strength. Also, XRD, FTIR, and SEM techniques were employed to evaluate the phase composition, the chemical groups and the morphological aspects of the porous cements during setting. It was found that the presence of a porogen in a CPC led to significant decreases in both its initial setting time and compressive strength. A CPC made using acetic acid contained a larger amount of the apatite phase but was significantly less injectable and less porous than when citric acid was used. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008 [source] CRISPY/CRUNCHY CRUSTS OF CELLULAR SOLID FOODS: A LITERATURE REVIEW WITH DISCUSSIONJOURNAL OF TEXTURE STUDIES, Issue 5 2004HANNEMIEKE LUYTEN ABSTRACT Literature on the crispy/crunchy behavior of cellular solid foods with a crust is discussed. The emphasis is on products with a dry crispy or crunchy crust as bread and various snacks and especially on mesoscopic and macroscopic aspects. Successively, the sensory sensations involved, the mechanical and fracture behavior of crispy/crunchy products, morphological aspects, and the relation between crispy and crunchy behavior and mobility of the macromolecules and plasticizer (primarily water) involved, are discussed. Finally, some ideas for an integrated approach of crispy/crunchy behavior of cellular solid foods with a dry crust will be discussed. [source] Genetic and ecological divergence of a monophyletic cichlid species pair under fully sympatric conditions in Lake Ejagham, CameroonMOLECULAR ECOLOGY, Issue 6 2001Ulrich Schliewen Abstract Although there is mounting evidence that speciation can occur under sympatric conditions, unambiguous examples from nature are rare and it is almost always possible to propose alternative allopatric or parapatric scenarios. To identify an unequivocal case of sympatric speciation it is, therefore, necessary to analyse natural settings where recent monophyletic species flocks have evolved within a small and confined spatial range. We have studied such a case with a cichlid species flock that comprises five Tilapia forms endemic to a tiny lake (Lake Ejagham with a surface area of approximately 0.49 km2) in Western Cameroon. Analysis of mitochondrial D-Loop sequences shows that the flock is very young (approximately 104 years) and has originated from an adjacent riverine founder population. We have focused our study on a particular pair of forms within the lake that currently appears to be in the process of speciation. This pair is characterized by an unique breeding colouration and specific morphological aspects, which can serve as synapomorphic characters to prove monophyly. It has differentiated into a large inshore and a small pelagic form, apparently as a response to differential utilization of food resources. Still, breeding and brood care occurs in overlapping areas, both in time and space. Analysis of nuclear gene flow on the basis of microsatellite polymorphisms shows a highly restricted gene flow between the forms, suggesting reproductive isolation between them. This reproductive isolation is apparently achieved by size assortative mating, although occasional mixed pairs can be observed. Our findings are congruent with recent theoretical models for sympatric speciation, which show that differential ecological adaptations in combination with assortative mating could easily lead to speciation in sympatry. [source] Perineurioma of the mandibular dental nerve: a case report and review of the literatureORAL SURGERY, Issue 2 2009E.F. Vencio Abstract Perineurioma is an uncommon benign tumour of the nerve sheath composed exclusively of well-differentiated perineurial cells. It usually affects the limbs or trunk; intraoral lesions are uncommon. A rare case of perineurioma is described involving the mandibular dental nerve in a 59-year-old female, microscopically characterised by a combined pattern of intraneural and soft tissue perineurioma. The patient was referred for treatment of a lesion in the mandible. Panoramic radiography revealed a well-delimited osteolytic lesion with radiopaque halo in an edentulous region of the left mandible. Occlusal view showed no expansion of cortical bone. A surgical procedure for incisional biopsy disclosed a connection between the tumour and the alveolar inferior nerve. Grossly, an enlargement of the affected nerve was described. Microscopic examination showed tumour cells arranged in pseudo-onion bulb structures, with scattered collagen bundles, and areas with a whorled (storiform) arrangement. Many concentric whorls of spindle cells exhibiting thin, elongated eosinophic processes were seen. Immunohistochemical study exhibited strong positivity for epithelial membrane antigen. We report a rare case of perineurioma affecting the mandibular dental nerve showing both intraneural and soft tissue microscopic patterns and discuss morphological aspects for differential diagnosis. [source] New strepsirrhine primate from the late Eocene of Peninsular Thailand (Krabi Basin)AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 4 2006Laurent Marivaux Abstract In this paper, we describe the newly discovered lower jaw of a primate from the late Eocene Krabi coal mine (Bang Mark pit) of Peninsular Thailand. We performed microtomographic examinations at the European Synchrotron Radiation Facility (ESRF, Grenoble, France) to analyze different morphological aspects of the jaw and teeth. Although partially preserved, this fossil mandible reveals a set of distinctive dental traits (e.g., double-rooted P2 and molarized P4) that allow us to describe a new stepsirrhine adapiform: Muangthanhinius siami, new genus and species. This taxon is somewhat atypical among Paleogene adapiforms, and more specialized than the sivaladapid adapiforms (hoanghoniines) that existed in Asia in the same epoch. In fact, Muangthanhinius shows a degree of dental specialization approximating that of some modern strepsirrhine lemuriforms, although it lacks the highly specialized anterior dentition characterizing this living primate group (canine + incisors forming a very procumbent toothcomb). In contrast, Muangthanhinius exhibits a large canine deeply anchored within the dentary that probably protruded high above the toothrow. Finally, despite the development of a molarized P4 as in Miocene sivaladapid sivaladapines, Muangthanhinius differs in molar morphology from this group, and the position of this new taxon within the Adapiformes remains indeterminate. Clarification of its phylogenetic position will require more morphological evidence than is currently available. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source] Compartmentalization of the precheliceral neuroectoderm in the spider Cupiennius salei: Development of the arcuate body, optic ganglia, and mushroom bodyTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 13 2010Carola Doeffinger Abstract Similarly to vertebrates, arthropod brains are compartmentalized into centers with specific neurological functions such as cognition, behavior, and memory. The centers can be further subdivided into smaller functional units. This raises the question of how these compartments are formed during development and how they are integrated into brain centers. We show here for the first time how the precheliceral neuroectoderm of the spider Cupiennius salei is compartmentalized to form the distinct brain centers of the visual system: the optic ganglia, the mushroom bodies, and the arcuate body. The areas of the visual brain centers are defined by the formation of grooves and vesicles and express the proneural gene CsASH1, followed by expression of the neural differentiation marker Prospero. Furthermore, the transcription factor dachshund, which is strongly enriched in the mushroom bodies and the outer optic ganglion of Drosophila, is expressed in the optic anlagen and the mushroom bodies of the spider. The developing brain centers are further subdivided into single neural precursor groups, which become incorporated into the grooves and vesicles but remain distinguishable throughout development, suggesting that they encode spatial information for neural subtype identity. Several molecular and morphological aspects of the development of the optic ganglia and the mushroom bodies are similar in the spider and in insects. Furthermore, we show that the primary engrailed head spot contributes neurons to the optic ganglia of the median eyes, whereas the secondary head spot, which has been associated with the optic ganglia in insects and crustaceans, is absent. J. Comp. Neurol. 518:2612,2632, 2010. © 2010 Wiley-Liss, Inc. [source] | ||||||||||||||||