Optimized tissue sample preparation for cryo-electron tomography using serial lift-out.

Cryo-electron tomography (cryo-ET) can provide invaluable insights into subcellular structures in their native environment at molecular resolution. Cryo-focused ion beam (cryo-FIB) has been widely adopted to obtain thin lamellae of cells suitable for tomographic data acquisition. However, its application to tissue samples faces significant limitations. The larger sample size extends milling time, reducing sample preparation throughput. Furthermore, the need for repeated, intricate lift-out procedures adds considerable time and complexity to the workflow. The serial lift-out technique, which can prepare multiple lamellae, increases throughput and better preserves the structural integrity of the tissue sample. Here we outline the workflow of the optimized serial lift-out method and provide a detailed protocol for its implementation, exemplified by a vitrified mouse liver tissue sample.