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Serial Block-Face SEM for Life Science

3D Ultrastructural Imaging for Life Sciences

Understanding the 3D ultrastructure of cells, tissues and organelles is essential for unravelling fundamental biological processes, explaining disease mechanisms and advancing treatment strategies, all of which enable researchers to make groundbreaking progress in various fields within the life sciences. Serial block-face scanning electron microscopy (SBFSEM) utilises a microtome with a diamond knife mounted inside the SEM chamber to repeatedly cut away a thin layer of sample, after which the freshly exposed surface is imaged. This process is repeated thousands of times, and the serial images are used to build up 3D visualisations of biological ultrastructures at the nanoscale. The ConnectomX katana microtome is a universal, compact and user-friendly in-situ microtome which allows the user to perform fully automated SBFSEM on with a slice thickness down to 20nm, allowing the user to build up high-resolution volume data over large sample volumes. Here, we show a large volume, high-resolution squid skin dataset acquired using SBFSEM to demonstrate how katana microtome allows researchers to visualise the 3D ultrastructures of tissues and cells and continue to push boundaries in all fields of life sciences.

Squid Skin

Camouflage using Chromatophores

Squids, and other cephalopods, are some of the few animals in the world with the incredible ability to change the colour of their skin, allowing them to blend into their surroundings making them difficult to locate. Thousands of specialist pigment-containing cells called chromatophores just below the surface of the skin are responsible for this remarkable behaviour. Each chromatophore contains an elastic sac full of pigment. A complex array of nerves and muscles attached to the sac can expand it causing the pigment to become more visible, changing the colour of the skin. SBFSEM with katana microtome allows for high-resolution 3D imaging of the chromatophore providing researchers with the ability to visualise the nanoscale ultrastructure to examine their arrangement and connectivity at the cellular and sub-cellular level. paving the way for significant advancements in the understanding of the adaptive chromogenic behaviour of these fascinating organisms.

Fig 1. (a0 Overview volumetric dataset (743µm x 551µm x 30µm) of a squid skin sample made up of 600 serial images with a slice thickness of 50nm. (b) Image of the pigment sack taken from a high-resolution montaged ROI with pixel size 24nm. (c) Volume rendering of the cropped region of the squid skin sample highlighted in (b). (d) (e) Renderings of the end of the cytoelastic sacculus extracted from the ROI shown in (c). All images were 5120 x 3840 acquired using katana microtome installed on a JEOL JSM-7800FLV SEM.


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