Serial block-face scanning electron microscopy (SBEM) is a powerful technique used to perform 3D imaging with nanometer resolution. An ultramicrotome is installed inside a scanning electron microscope (SEM) chamber. The SEM will collect an image of the block face after each cut of the ultramicrotome.
The method have proved particularly useful in neuroscience as significant portions of neural circuits can now be visualised and mapped.
Correlative 3D electron microscopy using 3view microscope
The BioEM facility has developed a method, using SBEM, that does not require introducing any fiducial marks, or the need to section and image massive volumes of tissue to reliably find axons and dendrites previously imaged with light microscopy (Maclachlan et al., 2018).
The approach relies on the natural landmarks, such as blood vessels and cell bodies. It only requires low-resolution imaging, of the entire section, using transmitted light, combined with high-resolution confocal imaging of the structures of interest. This need to be done before the tissue section is heavy-metal stained and resin embedded (see protocol). Then a block is prepared using the blood vessel pattern and trimmed edges to precisely positioned the region of interest under EM. SBEM imaging can then collect images that reveal the exact location of the relevant structures.