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In a comprehensive study, we demonstrate the performance and typical application scenarios for laboratory-based nano-computed tomography in materials research on various samples. Specifically, we focus on a projection magnification system with a nano focus source. The imaging resolution is quantified with common 2D test structures and validated in 3D applications by means of the Fourier Shell Correlation. As representative application examples from nowadays material research, we show metallization processes in multilayer integrated circuits, aging in lithium battery electrodes, and volumetric of metallic sub-micrometer fillers of composites. Thus, the laboratory system provides the unique possibility to image non-destructively structures in the range of 170–190 nanometers, even for high-density materials.
At the end of the first larval stage, the nematode Caenorhabditis elegans developing in harsh environmental conditions is able to choose an alternative developmental path called the dauer diapause. Dauer larvae exhibit different physiology and behaviors from non-dauer larvae. Using focused ion beam-scanning electron microscopy (FIB-SEM), we volumetrically reconstructed the anterior sensory apparatus of C. elegans dauer larvae with unprecedented precision. We provide a detailed description of some neurons, focusing on structural details that were unknown or unresolved by previously published studies. They include the following: (1) dauer-specific branches of the IL2 sensory neurons project into the periphery of anterior sensilla and motor or putative sensory neurons at the sub-lateral cords; (2) ciliated endings of URX sensory neurons are supported by both ILso and AMso socket cells near the amphid openings; (3) variability in amphid sensory dendrites among dauers; and (4) somatic RIP interneurons maintain their projection into the pharyngeal nervous system. Our results support the notion that dauer larvae structurally expand their sensory system to facilitate searching for more favorable environments.
Cataglyphis ants are known for their outstanding navigational abilities. They return to their inconspicuous nest after far‐reaching foraging trips using path integration, and whenever available, learn and memorize visual features of panoramic sceneries. To achieve this, the ants combine directional visual information from celestial cues and panoramic scenes with distance information from an intrinsic odometer. The largely vision‐based navigation in Cataglyphis requires sophisticated neuronal networks to process the broad repertoire of visual stimuli. Although Cataglyphis ants have been subjected to many neuroethological studies, little is known about the general neuronal organization of their central brain and the visual pathways beyond major circuits. Here, we provide a comprehensive, three‐dimensional neuronal map of synapse‐rich neuropils in the brain of Cataglyphis nodus including major connecting fiber systems. In addition, we examined neuronal tracts underlying the processing of visual information in more detail. This study revealed a total of 33 brain neuropils and 30 neuronal fiber tracts including six distinct tracts between the optic lobes and the cerebrum. We also discuss the importance of comparative studies on insect brain architecture for a profound understanding of neuronal networks and their function.
Der Mandelkernkomplex (Amygdala) ist ein Kerngebiet im medialen Temporallappen, das zum limbischen System gehört und dem eine wichtige Rolle in der Regulation von Gefühlen, sozialem Verhalten, Affekten, Gedächtnis und Sexualität zugeschrieben wird. Die mit Hilfe der 3D-Software Amira erstellten dreidimensionalen Rekonstruktionen des Mandelkernkomplexes von Kontrollfällen und Personen mit M. Alzheimer, Chorea Huntington, M. Little und Megalenzephalie basierten auf den mikroskopisch ausgewerteten zytoarchitektonischen Abgrenzungen der amygdaloiden Kerngebiete der nach Nissl gefärbten Hirnschnittpräparate. Die quantitativen Ergebnisse wurden mit bewährten stereologischen Methoden verglichen und den mit Post-mortem- und In-vivo-Verfahren generierten Ergebnissen anderer Studien gegenüber gestellt. Dabei wurden die Nomenklatur und die Abgrenzung der einzelnen Kerne diskutiert und auf exogene und biologische Volumen und Zelldichte beeinflussende Faktoren eingegangen, die die exakte und reproduzierbare Volumenbestimmung des menschlichen ZNS und seiner Komponenten erschweren. Unter Berücksichtigung von Schrumpfungsfaktoren und mehr oder minder großen Differenzen in der Abgrenzung des Mandelkernkomplexes sind die eigenen Daten mit bisher veröffentlichten Untersuchungen gut vergleichbar. Die in dieser Arbeit beschriebene Methode der dreidimensionalen Rekonstruktion von Hirnstrukturen eröffnet neue Möglichkeiten der Darstellung und Animation, die entscheidende wissenschaftliche Kenntnisse und wichtige Hinweise zur Auswertung MRT-basierter Morphometrie liefern und damit zur Diagnostik neuropsychiatrischer Erkrankungen beitragen kann.