Quaternary tectonics and seismic stratigraphy of the western Black Sea shelf

Interpretation of high and very high resolution reflection seismic data from the western Black Sea shelf yielded a seismic stratigraphic model of the Late Quaternary deposits on the southwestern Black Sea shelf. This model was combined with borehole information to carry out a regional subsidence analysis, so that the influence of tectonics and sediment compaction could be ruled out in the estimation of sea-level changes in the Black Sea. Mio-Pliocene sediments form the baseline of the interpretation. On top of it four Quaternary seismic stratigraphic units were identified on the western Black Sea shelf; they are named in chronological order Unit 4 to Unit 1 (U4 U1). Pliocene deposits are built up by gently basinward dipping layers of relatively high and approximately uniform thickness. Buried graben structures attest to the influence of extensional tectonics until the Upper Pliocene. Later, strong erosion left a rugged surface on the inner and middle shelf that was later overlain by a thin layer of Quaternary to Holocene sediments. The Pliocene is followed by the oldest observed Quaternary seismic sequence (Unit 4, U4); it comprises layers of Lower Quaternary age that dip towards the basin at a steeper angle than those of the Pliocene. Within U4 the oldest of three Quaternary shelfedge delta systems in the study area was found, that supposedly marks an Early Quaternary sea-level lowstand...thesi

Scanning Electron Microscopy of Corrosion Casting in Medicine

The aims of this review are: 1. to provide a bibliography of the publications that have used the corrosion casting technique; 2. to describe the advantages and limitations of the methodology; 3. to illustrate possible applications in the field of medicine, and 4. to highlight the significance of this method in the teaching of medical students. Thus, this paper is primarily focused on the scanning electron microscopical examination of vascular corrosion casts. The unsurpassed three-dimensionality of the corrosion casting technique compared to any other means stands out in particular. This can be especially useful when complex vascular-anatomical relationships are present. This applies not only to the portrayal of the modes of branching and varying vascular densities but also to regulatory arrangements, such as sphincters and arteriovenous anastomoses. Between 1966 and 1990, a total of 549 publications were found in the Medline literature data bank, containing the key words corrosion casting , microvascular cast , or vascular cast (as of August, 1990). Of those publications, most dealt with applications to experimental animals. By contrast, only 142 reports were mainly or partially concerned with human investigational material. The normal vascular system of nearly all organs, insofar as this is of direct medical relevance, has been largely resolved. In our opinion, one of the most important potential applications of the corrosion casting technique lies in the investigation of gastrointestinal, renal or hepatic ailments, which coincide with the reconstruction or rarefication of the vascular bed, e.g., in ulcers, ileitis terminalis, colitis ulcerosa, cirrhosis or glomerulonephritis

The Vascularization of the Vertebral Column of Rats

The intrinsic and extrinsic blood supplies of the vertebral column of rats have been examined by corrosion cast with Mercox CL2B(R). The close functional and topographic relationship of vessels to supplied structures were exposed by fractionated maceration of the soft tissues. The segmental arteries diverge into an anterior, median and posterior group with various anastomoses between their branches. Vertebral bodies and intervertebral discs are preferably supplied by branches of the anterior and median section. The vessels reaching the vertebral body from the dorsal side diverge in a treelike branching mode into the direction of the vertebral endplate. The venous drainage Lakes place by the segment-overlapping internal and external vertebral venous plexuses. Blood flow regulating sphincters can be identified within all parts of the arterial and venous system. This fact seems to be of great importance regarding pathophysiological processes of degeneration and likewise regeneration even of the intervertebral discs

The Vascular System of Xenotransplanted Tumors -Scanning Electron and Light Microscopic Studies-

A widely used model for investigating basic tumor characteristics and different treatment modalities preclinically is the immune-deficient, athymic nude mouse. This model offers many morphological parallelisms to the clinical situation. The aim of this study is to demonstrate the vascularization pattern of xenotransplanted human melanomas and sarcomas using different methods. Xenotransplanted tumors of 62 congenital thymusaplastic nude mice were examined ultrastructurally and topographically after corrosion cast and tissue preparation. Quantitative measurements of tumors injected with India ink were carried out to obtain comparable information on the vascular densities in the tumors. Quantitative measurements showed that there is no zonal, topographic arrangement of the vascular densities. Comparisons of the vascular densities in the centers of tumors with the densities in the periphery showed an extreme heterogeneity in tumor vessel distribution, which does not generally support the idea of a better vascularisation in the tumor periphery. Neither in the periphery nor in the center of the tumor regular vessels are to be seen consisting of intimal, medial and adventitial layers. Even the largest peripheral vessels, which often take a tortuous course, consist mainly of an endothelial layer and some perivascular connective tissue only. Areas with high vascular densities could be seen just beneath areas almost free of vessels. Besides endothelial-lined vessels numerous irregular, tumor cell-lined sinusoids are visible both in sarcomas and melanomas. The morphology of the vessels found scanning electron microscopically is generally in agreement with many features described transmission electron microscopically

The Vascularization of the Peripheral Nerve of Chicken and Rat

The vascular system of the sciatic nerve of chicken and rats was examined by means of the microcorrosion casting technique and freeze-broken specimens. The main epineural vessels form two lateral and interfascicular vascular bundles which anastomose with one another and also with the peri -and endoneural plexuses. On epi- and perineural vessels one can find morphological correlates for regulative means such as sphincters. Even the endoneural vessels depict numerous anastomoses. The proximity of the vessels as well as the great number of anastomoses suggests a considerable compensatory potential with an adaptable perfusion rate in case of a partial breakdown of a plexus

Impact of the Incubation Medium on the Endothelium of Autologous Vein Grafts: Damage Scoring by Scanning Electron Microscopy

The aim of this study was to examine the influence of different incubation media on the morphology of the endothelium of great saphenous vein grafts and establish a suitable scoring system for the evaluation of damage caused by these media. Fifty specimens of saphenous veins from ten patients during elective aorto-coronary bypass surgery were used. Ten specimens served as controls; the others were assigned to test groups and exposed to heparinized whole blood, Bretschneider\u27s HTK, human albumin or Ringer\u27s solution. Specimens exposed to heparinized blood showed only slight morphological alterations, whereas the other three mediums caused severe damage. Thus, heparinized blood seems to be most suitable as a rinsing and incubation medium. A widely accepted scoring system for the quantification of endothelial damage caused by the incubation media did not adequately reflect the morphological alterations in the cytoskeleton and membrane topology. The proposed scoring system, which is based on endothelial cell separation, endothelial cell loss, amount of deposits, endothelial cell surface homogeneity, in addition to the frequency of spikes and blebs, seems to be suitable for characterizing differences in endothelial morphology

Microvascular Corrosion Casting in the Study of Tumor Vascularity: A Review

Tumor blood flow is dependent on the structure and three-dimensional (3-D) architecture of the vascular network. The latter can be best studied by scanning electron microscopy of microvascular corrosion casts. However, literature reviews show that nearly all studies using this technique render comparisons of different tumors more difficult since they are mainly based on descriptive terms that might lead to misunderstandings. Qualitative comparisons of 13 experimental and 3 human primary tumors of different origin show a high degree of similarity in the vasculature. Quantitative analysis of these casts reveals similar ranges of parameters such as diameters, intervascular and interbranching distances. Diameters of vessels with capillary wall structure range from 6 μm to 55 μm in the human primary tumors (renal clear cell carcinoma, basalioma), and from 5 μm to 80 μm in xenografted tumors (sarcomas, colon carcinoma). Intervascular distances in the human primary tumors range from 2 μm to 52 μm, and from 11 μm to 105 μm in the xenografts. Interbranching distances range from 34 μm to 258 μmin the former, and from 11 μm to 160 μmin the latter. Both qualitative and quantitative analyses of tumor microvascular corrosion casts enable pathophysiological conclusions to be drawn and contribute to a better understanding of tumor vascularity

Arabisch als moderne Fremdsprache im Schulunterricht

Sowohl im wissenschaftlichen Diskurs als auch in der Schulpraxis fristet der Arabischunterricht als moderner Fremdsprachenunterricht ein Schattendasein. Mit dem vorliegenden Artikel wird er ins Licht gerückt: Nach der Darstellung der gesellschaftlichen Relevanz und des Bildungspotentials des Arabischunterrichts werden bezugnehmend auf ein Schulprojekt didaktische Überlegungen dargestellt sowie empirische Befunde zu Teilnahmemotiven bzw. -begründungen der Schülerinnen und Schüler berichtet. Es wird ein Ausblick auf die Integrierung der Arabischdidaktik in die Lehrerbildung gegeben.Both in academic discourse and school practice, teaching Arabic as a modern foreign language does not gain much attention. This article, however, spotlights Arabic didactics. After a delineation of the social relevance and the educational potential of Arabic tuition, some didactic considerations are reported on the basis of a teaching project. Empirical findings on students’ motives and reasons for participation are outlined. The article gives an outlook on the involvement of Arabic didactics in teacher education