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Abstract Intravital 2P-microscopy enables the longitudinal study of brain tumor biology in superficial mouse cortex layers. Intravital microscopy of the white matter, an important route of glioblastoma invasion and recurrence, has not been feasible, due to low signal-to-noise ratios and insufficient spatiotemporal resolution. Here, we present an intravital microscopy and artificial intelligence-based analysis workflow (Deep3P) that enables longitudinal deep imaging of glioblastoma up to a depth of 1.2 mm. We find that perivascular invasion is the preferred invasion route into the corpus callosum and uncover two vascular mechanisms of glioblastoma migration in the white matter. Furthermore, we observe morphological changes after white matter infiltration, a potential basis of an imaging biomarker during early glioblastoma colonization. Taken together, Deep3P allows for a non-invasive intravital investigation of brain tumor biology and its tumor microenvironment at subcortical depths explored, opening up opportunities for studying the neuroscience of brain tumors and other model systems.

Abstract Tissue integrity is sensitive to temperature, tension, age, and is sustained throughout life by adaptive cell-autonomous or extrinsic mechanisms. Safeguarding the remarkably-complex architectures of neurons and glia ensures age-dependent integrity of functional circuits. Here, we report mechanisms sustaining the integrity of C. elegans CEPsh astrocyte-like glia. We combine large-scale genetics with manipulation of genes, cells, and their environment, quantitative imaging of cellular/ subcellular features, tissue material properties and extracellular matrix (ECM). We identify mutants with age-progressive, environment-dependent defects in glial architecture, consequent disruption of neuronal architecture, and abnormal aging. Functional loss of epithelial Hsp70/Hsc70-cochaperone BAG2 causes ECM disruption, altered tissue biomechanics, and hypersensitivity of glia to environmental temperature and mechanics. Glial-cell junctions ensure epithelia-ECM-CEPsh glia association. Modifying glial junctions or ECM mechanics safeguards glial integrity against disrupted BAG2-proteostasis. Overall, we present a finely-regulated interplay of proteostasis-ECM and cell junctions with conserved components that ensures age-progressive robustness of glial architecture.

Stimulated Brillouin scattering (SBS) microscopy is a nonlinear all-optical imaging method that provides mechanical contrast based on the interaction of laser radiation and acoustical vibrational modes. Featuring high mechanical specificity and sensitivity, three-dimensional sectioning, and practical imaging times, SBS microscopy with (quasi) continuous wave excitation is rapidly advancing as a promising imaging tool for label-free visualization of viscoelastic information of materials and living biological systems. In this article, we introduce the theory of SBS microscopy and review the current state-of-the-art as well as recent innovations, including different approaches to system designs and data analysis. In particular, various performance parameters of SBS microscopy and its applications in the life sciences are described and discussed. Future perspectives for SBS microscopy are also presented.

Chan et al. apply Brillouin microscopy to study changes in tissue material properties during mammalian follicle development. Focusing on the Brillouin loss tangent which is independent of the refractive index and mass density, they find that mammalian folliculogenesis is characterised by region-specific changes in tissue micro-viscosity driven by cell differentiation and extracellular matrix remodelling.

Mehmet S. Ozturk et al. present an intravital mesoscopic fluorescence tomography (IFT) technique that is capable of tracking fluorescently labeled tumor cells inside living mice over several months. It demonstrates a promising new method for studying tumor growth dynamics in a quantitative and longitudinal fashion in-vivo.

All-optical ultrasound detection bears a number of unique advantages for photoacoustic tomography, including the ability for high resolution sampling of the acoustic field and its compatibility with a wide variety of other optical modalities. However, optical schemes based on miniaturized cavities are sensitive to optical aberrations as well as manufacturing-induced cavity imperfections which degrade sensor sensitivity and deteriorate photoacoustic image quality. Here we present an experimental method based on adaptive optics that is capable of enhancing the overall sensitivity of Fabry-Pérot based photoacoustic sensors. We experimentally observe clear improvements in photoacoustic signal detection as well as overall image quality after photoacoustic tomography reconstructions when applied to mammalian tissues in vivo.

In this work we present three-dimensional (3D) measurements of Brillouin scattering spectra of the in-vivo zebrafish larvae eye. This dataset was obtained by Brillouin microscopy, an emerging all-optical and non-contact technique that gives access to material properties through the process of Brillouin scattering. Herein, we share a representative 3D dataset of spectral properties of 48–52 h post-fertilization (hpf) zebrafish embryos. These spectral properties can be related to a complex longitudinal modulus and thus elastic and viscous properties given knowledge of refractive index and material density. The dataset encompasses the crystalline lens as well as several different retinal layers. This data provides a valuable resource as well as a starting point for researchers interested in the mechanobiology of vertebrate eye development.

The detection limit of human vision has remained unclear. Using a quantum light source capable of generating single-photon states of light, authors here report that humans can perceive a single photon incidence on the eye with a probability above chance.