Helically arranged cross struts in azhdarchid pterosaur cervical vertebrae and their biomechanical implications

Azhdarchid pterosaurs, the largest flying vertebrates, remain poorly understood, with fundamental aspects of their palaeobiology unknown. X-ray computed tomography reveals a complex internal micro-architecture for three-dimensionally preserved, hyper-elongate cervical vertebrae of the Cretaceous azhdarchid pterosaur, Alanqa sp. Incorporation of the neural canal within the body of the vertebra and elongation of the centrum result in a "tube within a tube" supported by helically distributed trabeculae. Linear elastic static analysis and linearized buckling analysis, accompanied with a finite element model, reveal that as few as 50 trabeculae increase the buckling load by up to 90%, implying that a vertebra without the trabeculae is more prone to elastic instability due to axial loads. Subsuming the neural tube into the centrum tube adds considerable stiffness to the cervical series, permitting the uptake of heavy prey items without risking damage to the cervical series, while at the same time allowing considerable skeletal mass reduction.

Three-dimensional understanding of the morphological complexity of the human uterine endometrium

The fundamental morphology of the endometrial glands is not sufficiently understood by 2D observation because these glands have complicated winding and branching patterns. To construct a large picture of the endometrial gland structure, we performed tissue-clearing-based 3D imaging of human uterine endometrial tissue. Our 3D immunohistochemistry and layer analyses revealed that the endometrial glands form a plexus network in the stratum basalis and expand horizontally along the muscular layer, similar to the rhizome of grass. We then extended our method to assess the 3D morphology of tissue affected by adenomyosis, a representative "endometrium-related disease," and observed its 3D morphological features, including the direct invasion of endometrial glands into the myometrium and an ant colony-like network of ectopic endometrial glands within the myometrium. Thus, further understanding of the morphology of the human endometrium based on 3D analysis will lead to the identification of the pathogenesis of endometrium-related diseases.

Densities and numbers of calbindin and parvalbumin positive neurons across the rat and mouse brain

The calcium-binding proteins parvalbumin and calbindin are expressed in neuronal populations regulating brain networks involved in spatial navigation, memory processes, and social interactions. Information about the numbers of these neurons across brain regions is required to understand their functional roles but is scarcely available. Employing semi-automated image analysis, we performed brain-wide analysis of immunohistochemically stained parvalbumin and calbindin sections and show that these neurons distribute in complementary patterns across the mouse brain. Parvalbumin neurons dominate in areas related to sensorimotor processing and navigation, whereas calbindin neurons prevail in regions reflecting behavioral states. We also find that parvalbumin neurons distribute according to similar principles in the hippocampal region of the rat and mouse brain. We validated our results against manual counts and evaluated variability of results among researchers. Comparison of our results to previous reports showed that neuron numbers vary, whereas patterns of relative densities and numbers are consistent.

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Brain-wide, semi-automatic quantification of parvalbumin and calbindin neurons

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Largely complementary distribution of calbindin and parvalbumin neurons in mice

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Comparison with several previous studies shows variable numbers but similar trends

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Similar distribution of parvalbumin neurons in the rat and mouse hippocampal region

Multiscale ATUM-FIB Microscopy Enables Targeted Ultrastructural Analysis at Isotropic Resolution

Volume electron microscopy enables the ultrastructural analysis of biological tissue. Currently, the techniques involving ultramicrotomy (ATUM, ssTEM) allow large fields of view but afford only limited z-resolution, whereas ion beam-milling approaches (FIB-SEM) yield isotropic voxels but are restricted in volume size. Now we present a hybrid method, named ATUM-FIB, which combines the advantages of both approaches. ATUM-FIB is based on serial sectioning of tissue into “semithick” (2–10 μm) sections collected onto tape. Serial light and electron microscopy allows the identification of regions of interest that are then directly accessible for targeted FIB-SEM. The set of semithick sections thus represents a tissue “library” which provides three-dimensional context information that can be probed “on demand” by local high-resolution analysis. We demonstrate the potential of this technique to reveal the ultrastructure of rare but pathologically important events by identifying microglia contact sites with amyloid plaques in a mouse model of familial Alzheimer's disease.

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Fast nanometer-resolution relocation and 3D imaging of preselected structures

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Transparent tape-based multiscale light and volume electron microscopy

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Heated ultramicrotomy at 2–10 μm with precured epoxy resin

A Comprehensive Integrated Anatomical and Molecular Atlas of Rat Intrinsic Cardiac Nervous System

We have developed and integrated several technologies including whole-organ imaging and software development to support an initial precise 3D neuroanatomical mapping and molecular phenotyping of the intracardiac nervous system (ICN). While qualitative and gross anatomical descriptions of the anatomy of the ICN have each been pursued, we here bring forth a comprehensive atlas of the entire rat ICN at single-cell resolution. Our work precisely integrates anatomical and molecular data in the 3D digitally reconstructed whole heart with resolution at the micron scale. We now display the full extent and the position of neuronal clusters on the base and posterior left atrium of the rat heart, and the distribution of molecular phenotypes that are defined along the base-to-apex axis, which had not been previously described. The development of these approaches needed for this work has produced method pipelines that provide the means for mapping other organs.

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Comprehensive single-neuron-scale mapping of the intrinsic cardiac nervous system

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Whole-organ high-throughput imaging and reconstruction at a cellular resolution

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3D anatomical framework for spatially tracked single-neuron molecular phenotypes

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Integrated histology, neuron mapping, and molecular profiles for 3D organ reconstruction