Serial block-face scanning electron microscopy (SBFSEM) is a method to generate high resolution three-dimensional images from biological samples such as brain tissue.[1] It consists of an ultramicrotome mounted inside the vacuum chamber of a scanning electron microscope. The surface of the block of resin-embedded fixed tissue (not the cut sections!) is imaged via detection of back-scattered electrons. After each section, the tissue block is raised by a tiny amount (less than 50 nm) to stay in focus. The machine can acquire many thousands of images in perfect alignment in an automated fashion. SBFSEM has been invented in 2004 by Winfried Denk at the Max-Planck-Institute in Heidelberg and is commercially available from Gatan Inc[2].
One of the first applications of SBFSEM is to analyze the wiring diagram of small regions of the brain. The resolution is sufficient to trace even the thinnest axons and to identify synapses. As a result of the extremely large datasets that a technique like this can produce one of the biggest challenges is to develop algorithms for automatic segmentation of the very large (~TByte) datasets generated by SBFSEM.
As the microtome is able to cut many types of samples this technique is starting to catch on in many other areas ranging from cell and developmental biology to materials science.