Mesoscopic Oblique Plane Microscopy via Light-sheet Mirroring

Understanding the intricate interplay and inter-connectivity of biological processes across an entire organism is important in various fields of biology, including cardiovascular research, neuroscience, and developmental biology. Here, we present a mesoscopic oblique plane microscope (OPM) system that enables whole organism imaging with high speed and subcellular resolution. It synergistically combines concepts of mirror based light-sheet microscopy, diffractive OPM, tiling light-sheet microscopy, projective imaging as well as a new lens-less galvo scanning technique. Using low magnification objectives with a large field of view, we realize mesoscopic imaging over a volume of 3.7x1.5x1 mm³ with a lateral resolution of ~2.3 microns and volume rates of ~5 Hz and projection imaging at 12 Hz. Applying the mesoscopic OPM, we demonstrate in vivo and in toto whole organism imaging of the zebrafish vasculature and its endothelial nuclei, and blood flow dynamics at 12 Hz. Together with optical flow analysis, we obtain a perfusion map and quantification of blood flow across the entire organism.