Many cells are too thick to study intact in cryo electron tomography.
Before the interior of a frozen-hydrated cell can be imaged, it must be thinned to electron transparency while maintaining cryogenic conditions. In order to do so, a Scios Cryo DualBeam™ cryo focused- ion-beam (cryo-FIB) microscope is used. Utilizing the ion beam of the cryo-FIB microscope, frozen specimens are thinned down to the appropriate thickness of 200-300 nm. Cryo-FIB milling [1, 2] opens relatively large and distortion-free windows into the cell’s interior,  enabling targeting of structural features within the cellular context.
Using a so called in-situ lamella milling or on-the-grid thinning strategy allows directly targeting vitrified cells on EM grids with the ion beam. Thereby, multiple regions of interest, containing high-quality electron cryo-lamellas, can be created straight on EM grids. These grids, harboring cryo-lamellas, are then transferred to either a Talos Arctica™ or Titan Krios™ transmission electron microscope for high-resolution imaging by cryo electron tomography.
Here I will discuss recent advances in cryo-FIB instrumentation and show how newly developed hardware and workflows facilitate cryo sample preparation.