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Histological Aspects (histological + aspect)
Selected AbstractsClinical and Histological Aspects of CNV Formation: Studies in an Animal ModelACTA OPHTHALMOLOGICA, Issue thesis2 2008Nathan Lassota MD Abstract. The purpose of the present thesis was to develop an animal model of CNV in order to study the early formation of CNV and to test the effects of an anti-angiogenic treatment. Porcine eyes were chosen as a substrate for CNV induction, since they are similar to human eyes in terms of both macroscopic and microscopic morphology. However, a major difference is that pigs lack a fovea; instead they have a visual streak, with a relatively stable and high concentration of cones. By surgical perforation of Bruch's membrane we were able to induce formation of CNV membranes. The morphology and cellular composition of these membranes varied with the surgical technique employed. When RPE cells were locally removed at the time of perforation, the resulting CNV was thinner, contained fewer blood vessels and was less prone to leak on fluorescein angiography than when RPE cells were left intact at induction. The neuroretina overlying the perforation site was not damaged by any of the surgical techniques, thus allowing the subsequent retinal damage to be ascribed to the actual process of CNV formation. Using this animal model allowed us to directly map histological findings onto fluorescein angiograms and thereby perform meaningful correlations between histopathologic and photographic features. Such correlations have been hampered in human subjects, since human eyes are not enucleated as a consequence of CNV and are therefore only available for post-mortem studies. In such studies there often is a considerable time-gap between the death of the patient and the latest available fluorescein angiogram, thereby allowing macular pathology to evolve in the interim. Histological examination of the porcine membranes demonstrated that they were composed of RPE cells, glial cells, macrophages, endothelial cells, collagen and smooth muscle fibres, which are the same cellular and fibrillar elements that dominate human CNV membranes. The porcine model was applied to test the effects, in a randomized and masked fashion, of intravitreally injected bevacizumab. Bevacizumab, a pan VEGF A antibody, was found to reduce both the proliferation of endothelial cells in CNV membranes and the propensity to leak in fluorescein angiograms. Immunohistochemically, bevacizumab was detected in the inner limiting membrane, in retinal blood vessels and binding uniformly to the entire CNV membrane without any cellular predisposition. Based on the above findings we believe that the porcine CNV model shows a bearing to human disease and therefore might be used as a tool to obtain improved treatments for this debilitating condition. [source] MICROMECHANICS: SIMULATING THE ELASTIC BEHAVIOR OF ONION EPIDERMIS TISSUEJOURNAL OF TEXTURE STUDIES, Issue 1 2006JIMMY LOODTS ABSTRACT A generic modeling approach is introduced that allows for dynamical simulations of cellular biological tissue. It is derived from the discrete element approach in the sense that the tissue is discretized such that histological aspects like cell geometry and the cellular arrangement within the tissue can be fully incorporated into the model. This makes dynamical simulations of arbitrarily shaped cellular tissues feasible in an elegant and a robust way. The validity of this simulation technique is demonstrated by a case study on the unicellular epidermis layer of onion (Allium cepa). The parameters of a two-dimensional model are determined using published stress,strain data from a tension test on longitudinal strips. The model is then validated quantitatively against the data for transversal strips. [source] Ex situ cultivation of Aplysinaaerophoba close to in situ conditions: ecological, biochemical and histological aspectsMARINE ECOLOGY, Issue 2 2008Anne Klöppel Abstract Sponges provide the largest number of biologically active natural products known from the marine environment and continue to be a very well studied phylum of marine fauna. The Mediterranean sponge Aplysina aerophoba accumulates brominated isoxazoline alkaloids such as Aplysinamisin-1, Aerophobin-2, Isofistularin-3 and the biotransformation product Aeroplysinin-1, which possesses, for example, antibiotic and cytotoxic properties. Until now, it is still being discussed which organisms , the sponge itself or associated microorganisms , are responsible for metabolite production. For cultivating Aplysina individuals under ex situ conditions, we surveyed relevant ecological factors in situ and controlled them in our aquarium system. We maintained A. aerophoba for more than 9 months and analysed changes of metabolite content and composition, microbial association as well as morphology in situ and ex situ under different light exposure. Although sponges showed slight reduction during maintenance, ex situ cultivation similar to in situ conditions provides a promising method to keep sponges and obtain their bioactive metabolites. [source] Observations on the female internal reproductive organs of the brown howler monkey (Alouatta guariba clamitans)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 2 2009Mariana Matera Veras Abstract Alouatta guariba clamitans (brown howler monkey) is an endemic primate from the southeastern Brazil tropical forests, classified as near threatened by the IUCN Red List 2007. The genus Alouatta is one of the most difficult New World monkeys to breed and rear in captivity. In this study we examined the macroscopic and histological aspects of the female genital tract of wild brown howler monkeys to provide baseline information for future reproduction research. The anatomical relationship between the vagina, uterus, broad ligament, oviducts and ovaries are those of a typical primate reproductive tract. The fundic portion of the uterus is globoid, the cervix is well developed, which confers to the uterus an elongated shape, and the vagina is a long flattened channel. Histological analysis conducted in females in the follicular phase revealed large quantities of interstitial luteinized tissue in the ovaries, a stratified nonkeratinized vaginal epithelium, lack of glands in the vaginal mucosa and simple tubular endometrial glands. The observed anatomical features should be considered in the adaptation and application of assisted reproductive techniques aimed at improving captive reproduction for species conservation. Am. J. Primatol. 71:145,152, 2009. © 2008 Wiley-Liss, Inc. [source] Histological Assessment of Selected Blood Vessels of the Phocid Seals (Northern Elephant and Harbour Seals)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 3 2010H. Smodlaka Summary Phocid seals exhibit vascular adaptations that allow them to undertake prolonged deep dives. These vascular adaptations are either unique to phocids, or are modified vascular equivalents to those present in terrestrial mammals. One such adaptation, the aortic bulb, is a spherical enlargement of the ascending aorta specific to phocid seals. Its histological make-up consists of a reinforced tunica media with circular and longitudinal layers of elastic fibres. This reinforcement enables multi-axial deformation of the aortic bulb, thus complementing its function as a prominent elastic reservoir or ,windkessel'. A second adaptation, the hepatic sinus, is an asymmetrical dilation of the abdominal portion of the caudal vena cava and accompanying hepatic veins. The hepatic sinus is comprised of a relatively thin tunica media, with a scant smooth muscle component. The bulk of the sinus wall is comprised of tunica adventitia. A third vascular adaptation distinctive to the phocids is the pericardial venous plexus, composed of convoluted veins circumnavigating the perimeter of the heart. Microscopically, these veins have a thick tunica media and also contain valves. Smaller arteries, venules and distinct capillary beds are observed interspersed in-between these veins. It can be hypothesized, that in seals, certain vascular embryonic development may be arrested at an earlier embryonic stage, resulting in these unusual vascular formations. These modifications play a vital role in blood pressure regulation and distribution of oxygenated blood during prolonged deep diving. The purpose of this work was to elucidate the histological aspects of these unique vascular modifications and relate them to specific function. [source] | ||||||||||