VIS2FIX: A High‐Speed Fixation Method for Immuno‐Electron Microscopy

Immuno‐transmission electron microscopy (TEM) is the technique of choice for high‐resolution localization of proteins in fixed specimen. Here we introduce 2 novel methods for the fixation of sections from cryo‐immobilized samples that result in excellent ultrastructural preservation. These high‐speed fixation techniques, both called VIS2FIX, allow for a reduction in sample preparation time from at least 1 week to only 8 h. The methods were validated in immuno‐TEM experiments on THP‐1 monocytes, human umbilical vein endothelial cells (HUVECs) and Madin–Darby canine kidney (MDCK‐II) cells. The fixation and retention of neutral lipids is demonstrated, offering unique prospects for the application of immuno‐TEM in the lipidomics field. Furthermore, the VIS2FIX methods were successfully employed in correlative fluorescence and electron microscopy.