SEM has been a reliable research tool in biological research for decades, and as such has been applied to various disciplines including botany, zoology, microbiology and physiology. Our different SEM platforms allow for the analysis of samples ranging from individual cell to larger tissue level. Correlative techniques such as CLEM further allow for the identification of specific proteins of interest within a sample. Larger structural analysis can also be performed through serial block-face (SBF) SEM on plant and tissue samples. Elemental analysis of biological samples is also possible, to asses heavy metal poisoning in biopsy samples for instance.
Figure 1. Micrograph of pollen. Acquired using the EVO SEM.
Figure 2. Citrus plant root samples acquired with different sample preparation techniques using the Apreo SEM. a) and b) represent SEM micrographs of cross-sections of dehydrated plant roots fixed in glutaraldehyde, c) micrograph of resin embedded plant root section at 500 nm thickness using an ultramicrotome.
Figure 3. Single serial block-face section of plant root containing algae and bacteria acquired with the Apreo Volumescope and prepared following a standard mega-metal and resin embedding protocol.
Figure 4,5. SEM images of a velvet worm using MERLIN, SE2 detector. Sample preparation was done using GLA fixation and ethanol series as dehydration step followed by HMDS for the final drying step.
Figure 6. SEM micrographs of dehydrated sea urchin samples at different magnifications using the Apreo SEM. a) Macro level tile scan of entire sample with region of interest (ROI) indicated in red, b) Structure of interest identified from ROI in tile scan, c) further magnification of structure of interest.
Figure 7. Snail tongue sample using MERLIN, SE2 detector.
Figure 8. Serial block-face (SBF) SEM 3D rendering of melanin containing cells in lizard skin samples obtained using the Apreo Volumescope SEM. Serial sections of samples prepared following an adapted mega-metal protocol were acquired at a z-width of 50 nm and aligned to generate a 3D image stack. 3D rendering of melanin containing ramifications are indicated in purple, cell nuclei in white and translucent colours indicate individual cells within the tissue samples. Scale bar 5 µm.
Figure 9. SEM micrographs of bacterial biofilms dehydrated through critical point drying acquired with the Apreo SEM.
Figure 10, 11. STEM micrographs acquired with the Apreo SEM of TB cells stained with osmium tetroxide, embedded in resin and sectioned at 100 nm thickness using an ultramicrotome.
Figure 12. EDX of TB cells stained with stained with osmium tetroxide, embedded in resin and sectioned at 100 nm thickness using an ultramicrotome. EDX was performed on the EVO SEM to assess iron (Fe) levels in individual TB cells indicated as spectrum 44 and 45. Results displayed as weight percentages.
Figure 13. STEM micrograph of algae cells prepared following a standard mega-metal and resin embedding protocol, sectioned at 100 nm using an ultramicrotome and acquired under the Apreo SEM.
Figure 14. Scanning transmission electron microscopy (STEM) imaging of HepG2 and HT-29 cells under treatment condition B and C. ms- swollen mitochondria; mr - ruptured mitochondria; arrow heads – phagophores around swollen and damaged mitochondria. Scale bar: 1µm.
Figure 15. Correlative Light and Electron Microscopy (CLEM) of brain cancer cells transfected with GFP-LC3-RFP- LC3ΔG and stained with LysoTracker Blue under control conditions. A) SEM micrograph of control U-118MG cell. B) Confocal fluorescent micrograph of U-118MG cell at 63x magnification displaying both TPMT and GFP-LC3 signal prior to image transformation. C) Transformed image that is spatially registered in the same orientation as the FESEM image in A. D) GFP-LC3 and E) FESEM images of the region of interest (ROI) outlined in C, with the corresponding overlay of these channels displayed in G. G1 and G2) Enhanced FESEM images of ROI 1 and 2 in G. White arrowheads indicate autophagosomes (A) and autolysosomes (AL). Scale bar 10 µm (images A-G) and 1 µm (image G1-G2).
Figure 16. Correlative Light and Electron Microscopy (CLEM) of blood clotting. A) Fluorescence micrograph of fibrin fibres. B) SEM micrograph of fibrin fibres associated with red blood cells. C) Overlay of fluorescence and SEM data.
Figure 17. Serial block-face (SBF) SEM of mouse lung tissue acquired under low-vacuum conditions to overcome the charging artifacts commonly presented by lung tissue. Samples were prepared using a standard mega-metal and resin embedding protocol for tissue and acquired using the Apreo Volumescope SEM. Orthogonal view of SBF dataset consisting of 200 z-slices at 50 nm z-width is showing as well as a 3D render of alveolar structures in a specific region of interest indicated in blue.
Figure 18. Serial block-face (SBF) SEM of neurons in mouse cerebral cortex. Samples were prepared using a standard mega-metal and resin embedding protocol for tissue and acquired using the Apreo Volumescope SEM. A) Individual high-resolution image of single SBF, B) Orthogonal view of SBF dataset consisting of 200 z-slices at 50 nm z-width. C) 3D rendering of individual neurons in region of interest outlined in red.