10. Vorlesung(05.05.2020): Hals-3-5

Vorlesungsinhalt: Derivate der Schlundbögen; Entwicklung der Zunge; Derivate der Schlundtaschen; Oesophagus; Larynxskelett; Interne Kehlkopfmuskeln; Larynx; Lymphbahnen des Laryn

9. Vorlesung (28.04.2020): Hals-2

Vorlesungsinhalt: Hautnerven; Topographische Einteilung des Halses; Lymphknoten; regionäre Lymphknoten der Zunge; Spatium lateropharyngeum; Tiefe Region; Plexus brachiali

Neuronal and glial regeneration after focal cerebral ischemia in rat, an immunohistochemical and electron microscopical study

Objectives: Unilateral middle cerebral artery occlusion (MCAO) is an established rat model for stoke studies. It induces focal cerebral ischemia, prior to necrotic and apoptotic loss of tissue in a circumscribed cortical area, paralleled by temporary motor impairment.Methods: Here we examined tissue samples from the peri-infarct zone of rats that had survived unilateral MCAO for up to 90 min. With immunohistochemistry we stained sections for proliferation markers Ki 67 and PCNA and for intermediate filament protein nestin. Electron microscopy was employed to assess ultrastructural changes.Results: All MCAO animals developed pronounced lesions in the motor cortex. Numerous cells in the immediate peri-infarct area and scattered cells which seem to have migrated into the infarcted lesion stained positively for Ki 67 and PCNA. Electron microscopy revealed that cells in the lesion site proliferate along the blood vessels. Most of these cells had the ultrastructural features of fibrillary astrocytes while some of the cells were clearly neurons. Endothelia were in part fenestrated. Some of the surrounding cells showed immunostaining for PCNA, indicating proliferation. Oligodendroglia and myelination could not be seen in the lesion site. Single neuronal contacts exhibited the ultrastructural features of synapses. Reformation of cortical layers could not be observed.Conclusions: We concluded that in spite of extensive proliferation; neuronal and glial regeneration occurs after MCAO only to a small extent. Revascularization seems to be an important initial step. The observed functional recovery of experimental animals may be due to neuronal plasticity in young rats rather than structural regeneration.Keywords: Middle cerebral artery occlusion, Rat stroke model, Neuronal regeneration, Revascularization in brain, Electron microscopy, Proliferation marker

Comparative evaluation of the impact on endothelial cells induced by different nanoparticle structures and functionalization

In the research field of nanoparticles, many studies demonstrated a high impact of the shape, size and surface charge, which is determined by the functionalization, of nanoparticles on cell viability and internalization into cells. This work focused on the comparison of three different nanoparticle types to give a better insight into general rules determining the biocompatibility of gold, Janus and semiconductor (quantum dot) nanoparticles. Endothelial cells were subject of this study, since blood is the first barrier after intravenous nanoparticle application. In particular, stronger effects on the viability of endothelial cells were found for nanoparticles with an elongated shape in comparison to spherical ones. Furthermore, a positively charged nanoparticle surface (NH2, CyA) leads to the strongest reduction in cell viability, whereas neutral and negatively charged nanoparticles are highly biocompatible to endothelial cells. These findings are attributed to a rapid internalization of the NH2-functionalized nanoparticles in combination with the damage of intracellular membranes. Interestingly, the endocytotic pathway seems to be a size-dependent process whereas nanoparticles with a size of 20 nm are internalized by caveolae-mediated endocytosis and nanoparticles with a size of 40 nm are taken up by clathrin-mediated internalization and macropinocytosis. Our results can be summarized to formulate five general rules, which are further specified in the text and which determine the biocompatibility of nanoparticles on endothelial cells. Our findings will help to design new nanoparticles with optimized properties concerning biocompatibility and uptake behavior with respect to the respective intended application